The URL can be used to link to this page

161205 MAD (Storm Drainage Report).pdf Madrona School Edmonds, Washington Storm Drainage Report December 2016 | Site Permit Madrona School – Edmonds School District i Storm Drainage Report December 2016 Prepared for: Edmonds School District 20420 68th Avenue West Lynnwood, WA 98036-7400 Prepared by: KPFF Consulting Engineers 1601 Fifth Avenue, Suite 1600 Seattle, WA 98101 (206) 622-5822 KPFF Job No. 1500129 Principal in Charge: Thaddeus J. Egging, PE Project Manager: Joss Gramstad, PE PRELIMINARY KPFF Consulting Engineers ii Madrona School – Edmonds School District iii Table of Contents 1. Project Description ........................................................................................................... 1 2. Stormwater Systems Overview .........................................................................................2 Existing Conditions ..................................................................................................................... 2 developed conditions.................................................................................................................. 2 3. Minimum Requirements ................................................................................................... 3 Minimum Requirement No. 1: Preparation of Stormwater Site Plan ........................................... 3 Minimum Requirement No. 2: Construction Stormwater Pollution Prevention (SWPP) .............. 3 Minimum Requirement No. 3: Source Control of Pollution .......................................................... 4 Minimum Requirement No. 4: Preservation of Natural Drainage Systems and Outfalls............... 4 Minimum Requirement No. 5: On-site Stormwater Management ............................................... 4 Minimum Requirement No. 6: Runoff Treatment ........................................................................ 4 Minimum Requirement No. 7: Flow Control ................................................................................ 4 Minimum Requirement No. 8: Wetlands Protection .................................................................... 4 Minimum Requirement No. 9: Basin/watershed planning ........................................................... 4 Minimum Requirement No. 10: Operation and Maintenance ...................................................... 5 4. Stormwater Design Requirements .................................................................................... 5 Code Compliance ....................................................................................................................... 5 Flow Control ............................................................................................................................... 6 Water Quality ............................................................................................................................. 6 Conveyance ................................................................................................................................ 6 5. Stormwater Pollution Prevention..................................................................................... 8 List of Figures Figure 1-1: Vicinity Map .................................................................................................................... 1 List of Tables Table 2-1: Existing TDAS ............................................................................................... 2 Table 3-1: Wetland B (North Basin) Land Cover............................................................. 5 Table 3-2: Wetland B (South Basin) Land Cover ............................................................ 5 Table 4-1: UIC Well Design ............................................................................................. 6 Table 4-2: Bioretention Cells with Underdrains Summary ............................................... 7 KPFF Consulting Engineers iv Appendices Appendix A – Site Maps Appendix B – Calculations and Program Output Appendix C – Geotechnical Engineering Report Appendix D - Hydrogeologic Report Appendix E - Wetland and Stream Delineation Report Appendix F – Wetland Hydroperiod Analysis Appendix G – Stormwater Pollution Prevention Plan Appendix H – Operations and Maintenance Manual Madrona School – Edmonds School District 1 1. Project Description The project is located at 9300 236th ST SW in Edmonds, Washington. The existing Madrona Elementary School will be demolished and replaced with a new school. The proposed school consists of a larger gymnasium and administration unit and five smaller classroom units. Other site improvements include new sports fields, play equipment, a bus drop-off loop, and parking lots. The new school will be situated in the field south of the existing school to enable phased construction while the existing school is in session. The project is disturbing the eastern 15 acres of a larger 40 acre parcel owned by the Edmonds School District. The site generally slopes from east to west with the lower southeast quarter of the site situated on a bench approximately 12 feet higher than the southwest quarter. The site is bound to the north by 236th St SW, to the east by a depressed wetland, to the south by 240th St SW, and to the west by a steep slope down to the former Woodway Elementary School. Water quality will be achieved through underdrained bioretention planters serving all of the pollution generating impervious surfaces. These planters are engineered to infiltrate at least 91% of the total runoff volume through the underdain. For flow control, the project is proposing a series of deep injection control wells. Storm drainage pipes and well fields have been analyzed to convey and infiltrate return events up to and including the 100-year event. The wetland to the east is largely dependent on the project site for its hydrology. A wetland analysis has been included to demonstrate how the project maintains the wetland function. Figure 1: Vicinity Map (NTS) SITE KPFF Consulting Engineers 2 This report is written according to the 2010 City of Edmonds Stormwater Code Supplement (Edmonds Supplement) and the 2005 Stormwater Management Manual for Western Washington (DOE Manual). 2. Stormwater Systems Overview EXISTING CONDITIONS The existing site is part of the larger Edmonds Way Watershed as defined on figure B – 1 in the Edmonds Supplement. The site is comprised of three Threshold Discharge Areas (TDA). TDA 1 includes the eastern half of 236th st and adjacent forested area as well as the eastern half of the staff parking lot and east driveway. TDA 1 drains through catch basins and pipes to the piped system in 236th St SW heading East to Edmonds Way. TDA 2 includes the eastern half of the site including half of the existing school, the southeastern field, and the large wetland. This Wetland is also known as Wetland B in the Wetland and Stream Delineation Report (See appendix E). Some offsite area from the neighboring residences also is included in TDA 2. Surface runoff either sheet flows directly to the wetland or is discharged via open pipe ends or dispersion trenches. Runoff in the wetland pools at the south end against the 240th St SW embankment until reaching the 18” culvert crossing the road. Downstream of the culvert, runoff is directed to the Edmonds Way system via open ditches and pipes. TDA 3 includes the western half of the site including the remaining half of 236th st and the existing school, parent parking lot, track, and south western field. TDA 3 either sheet flows or discharges via open pipe ends or dispersion trenches to the steep slope west of the site. Edmonds School District Maintenance staff has noted that during heavy rain, flowing water originating from the steep slope encroaches on the former Woodway Elementary school. Table 2-1: Existing TDAS TDA # (Name) Area (acres) #1 (Northeast 236th) 1.518 #2 (Wetland) 12.931 #3 (Steep Slope) 9.065 See Figure A1 in Appendix A for a map showing each of these areas. DEVELOPED CONDITIONS The proposed development includes approximately 6.72 acres of impervious area including parking lots, maintenance drives, building roof, and pedestrian courtyards. The proposed condition discharges runoff either to the existing system in 236th St SW, the groundwater table, or the wetland east of the site. UIC Well Sub-Basins There are three UIC well sub-basins that discharge runoff to the groundwater table. Madrona School – Edmonds School District 3 UIC Well Basin #1 contains five wells and is 3.239 acres of mostly impervious surfaces receiving runoff from the bus loop and parking lot areas. This UIC well field contains the majority of the pollution generating impervious surfaces. Bioretention and an oil water separator are proposed to provide water quality for 91% of the total runoff volume prior to discharging to the UIC wells. UIC Well Basin #2 contains five wells and is 3.083 acres receiving runoff from the track and interior play spaces. This sub basin is mostly pervious; however, the underdrained play field is modeled as impervious as runoff will enter the underdrains quickly. Water quality is not proposed for this basin as none of the surfaces are considered pollution generating. UIC Well Basin #3 contains three wells and is 1.324 acres of mostly impervious surfaces receiving runoff from building, lawn, the emergency access drive, and pedestrian courtyards. Water quality is not proposed for this basin as none of the surfaces are considered pollution generating. UIC Well Basin #4 contains three wells and is 1.936 acres of an almost equal amount of pervious and impervious surfaces receiving runoff from building, lawn, the emergency access drive, forest, and pedestrian courtyards. Water quality is not proposed for this basin as none of the surfaces are considered pollution generating. See Figure A3 in Appendix A for a map showing each of these areas. Wetland Sub-Basin The wetland sub-basin was designed to preserve the existing wetland hydrology in order to meet minimum requirement number 8. As the proposed development impacts the runoff pattern, a detailed analysis is included in section 3. All runoff from pollution generating impervious surfaces tributary to the wetland sub- basin are treated for water quality via bioretention. Non-pollution generating surfaces discharge directly through stabilized pipe outfalls or existing subsurface tile drains. See Figures F1 and F2 in Appendix F for maps of this area. 3. Minimum Requirements The project includes more than 5,000 square feet of new plus replaced impervious surfaces; therefore, all 10 of the Ecology Minimum Requirements are to be met. The following outlines project compliance: MINIMUM REQUIREMENT NO. 1: PREPARATION OF STORMWATE R SITE PLAN This storm drainage report, the appendices, and the submitted plans represent the Stormwater Site Plan as outlined in the Ecology Manual. MINIMUM REQUIREMENT NO. 2: CONSTRUCTION STORMWATER POLLUTION PREVENTION (SWPP) See Section 5, below. As the new plus replaced impervious surface is greater than 2,000 square feet, all 12 SWPP elements are to be met. See appendix G for the SWPP Plan. KPFF Consulting Engineers 4 MINIMUM REQUIREMENT NO. 3: SOURCE CONTROL OF POLLUT ION The proposed development does not contain pollution sources. As such, no source control BMPs have been proposed. The SWPP does include source control BMPs to be used during project construction. MINIMUM REQUIREMENT NO. 4: PRESERVATION OF NATURAL DRAINAGE SYSTEMS AND OUTFALLS The proposed drainage system will generally preserve the natural drainage patterns with the exception of discharge to the western steep slope. Most runoff from the developed site will infiltrate via the Underground Injection Control (UIC) wells. Runoff from 236th St SW will continue to drain to the existing roadway drainage system. The runoff patterns to the wetland east of the site will also be preserved. MINIMUM REQUIREMENT NO. 5: ON-SITE STORMWATER MANAG EMENT All of the stormwater from the project area will be infiltrated on site via the UIC wells or discharged directly to the wetland east of the site. See Section 4, below. MINIMUM REQUIREMENT NO. 6: RUNOFF TREATMENT Runoff treatment has been provided for 91% of the runoff volume from pollution generating impervious surfaces. See the “Runoff Treatment” portion of Section 4 below. MINIMUM REQUIREMENT NO. 7: FLOW CONTROL Flow control has been designed to meet this requirement through the use of infiltration through the UIC wells. See the “Flow Control” portion of Section 4, below. MINIMUM REQUIREMENT NO. 8: WETLAND PROTECTION The stormwater system has been designed to maintain the hydrologic conditions of the existing wetland. MGS Flood was utilized to model the existing land cover to determine the existing baseline hydrologic conditions, and a wetland hydroperiod analysis was conducted to compare the hydroperiod under the proposed conditions to that of the existing. Existing Wetland Conditions The existing conditions for Wetland B were modeled using a combination of contours from the project survey and the Edmonds GIS Map as well as the geotechnical engineer’s recommended infiltration rates. Due to the topography of the wetland, the wetland was modeled as two structures in MGS Flood to account for the north and south portions of the wetland: Wetland B-North and Wetland B-South. The north subbasin receives runoff from the surrounding area including residential area to the north and east and a portion of the Madrona School site to the west. Likewise, the south subbasin receives runoff from the surrounding area including the southeast portion of the site, as well as the outflow from Wetland B-North via a trapezoidal broad-crested weir. Wetland B-South discharges via an 18-inch culvert under 240th Street to the south. Wetland Hydroperiod Under Proposed Conditions Similar to the existing condition, stormwater from the eastern portion of the proposed Madrona School site drains to the wetland basin. The following tables (Table 3-1 and Table 3-2) compare existing surface areas to proposed surface areas for Wetland B’s north and south basins. Madrona School – Edmonds School District 5 Table 3-1: Wetland B (North Basin) Land Cover Existing (acres) Developed (acres) Difference (acres) Impervious 1.89 1.55 (0.34) Pervious (Forested) 2.57 2.57 0.00 Pervious (Landscaped Area) 1.71 2.45 0.74 TOTAL 6.17 6.57 0.40 Table 3-2: Wetland B (South Basin) Land Cover Existing (acres) Developed (acres) Difference (acres) Impervious 0.65 1.20 0.55 Pervious (Forested) 3.95 3.95 0.00 Pervious (Landscaped Area) 2.16 0.99 (1.17) TOTAL 6.76 6.14 (0.62) The proposed site land cover decreases the amount of impervious area in the Wetland B-North basin and increases the impervious area in the Wetland B-South basin. Since impervious surfaces produce proportionally more runoff, the total area that discharges to Wetland B-North increased and the area that discharges to Wetland B-South decreased in order to maintain the hydrologic conditions of the existing wetland basins. Using the wetland hydroperiod analysis tool in MGS Flood, the hydroperiod for the proposed conditions are compared to the existing condition for both the north and south portions of Wetland B. The MGS Flood report with the wetland hydroperiod analysis (Appendix F) demonstrates that the Stage Excursions Threshold (0.5 ft) and Amphibian Stage Excursions Threshold (0.25 ft from Feb 1 to May 31) are not exceeded in the proposed condition. MINIMUM REQUIREMENT NO. 9: BASIN/WATERSHED PLANNING No basin management is planned for this area. No additional requirements, beyond those listed above, are applicable to this project. MINIMUM REQUIREMENT NO. 10: OPERATION AND MAINTENAN CE Refer to Appendix H for the Operation and Maintenance Manual. 4. Stormwater Design Requirements CODE COMPLIANCE This project has been designed to meet the requirements of the Stormwater Code Supplement to Edmonds Community Development Code Chapter 18.30 and the 2005 Department of Ecology Stormwater Management Manual for Western Washington. KPFF Consulting Engineers 6 FLOW CONTROL Since the project is creating more than 10,000 square feet of effective impervious area, the Ecology Manual requires the implementation of flow control facilities and on-site stormwater management BMPs. Furthermore, stormwater discharges shall match pre-developed forested discharge rates and flow durations from 50 percent of the 2-year peak flow up to the full 50-year peak flow. The proposed flow control design meets or exceeds these requirements for sub-basins discharging to the water table. As the existing site does not include any flow control facilities and Minimum Requirement #8 requires wetland protection, predevelopment runoff peaks and durations were not maintained for sub-basins tributary to the eastern wetland. Reducing flows to the wetland through flow control would degrade the wetland’s function. UIC Well Design Through pilot test and full scale UIC well installations, the geotechnical engineer’s recommended long term UIC well infiltration rate is 3.3 gallons-per-minute per foot of screen. See the Hydrogeologic Report included in Appendix D. As the UIC wells each contain 50 feet of screen, the individual infiltrative capacity of each well is 165 GPM or 0.368 CFS. The table below shows the UIC well capacities compared to the 100 year peak flow using MGS Flood with one hour time steps. UIC Well Field 100-Year Flow (CFS) UIC Well Capacity (CFS) Minimum Wells Required Wells Provided Safety Factor 1 1.550 0.368 4.2 5 1.2 2 1.443 0.368 3.9 5 1.3 3 0.680 0.368 1.8 3 1.7 4 0.728 0.368 2.0 3 1.5 TOTAL UIC WELLS 12.0 16 1.3 Design of the UIC wells is based on the “Hydrogeologic Report” prepared by the project geotechnical engineer, Shannon and Wilson, Inc. and the “Guidance for UIC Wells that Manage Stormwater” as published by the Washington State Department of Ecology (Ecology), December 2006. Well design complies with the Ecology guidance for rule-authorized wells using the presumptive approach, and the UIC wells will be registered as Class V UIC wells with Ecology. Each UIC well will function as a deep dry well comprised, generally, of a borehole filled with gravel. Wells will be bored to approximately 120 feet below grade so as to access the deep advance outwash receptor horizon. Each well will have the upper 60-70 feet cased with 36-inch-diameter steel casing and will include a vertical conveyance pipe to allow high-flow infiltration and a separate piezometer tube to allow for testing and monitoring. Per the geotechnical investigations, the Qva aquifer is approximately at elevation 278 feet. The wells will be bored to approximately elevation 325; therefore, the bottom of each well will be approximately 47 feet above groundwater. WATER QUALITY Per the redevelopment requirements of Western Washington Ecology Manual, since the development includes more than 5,000 square feet of new plus replaced hard surfaces and the proposed improvements exceeds 50% of the assessed existing site improvement value, water quality treatment is required for pollution generating surfaces. Additionally, since the treatment facilities are designed using an approved Madrona School – Edmonds School District 7 continuous runoff model (MGS Flood), the water quality design storm volume shall be equal to the simulated daily volume that represents the upper limit of the range of daily volumes that accounts for 91% of the entire runoff volume over a multi-decade period of record. Water quality treatment to meet the above requirements will be provided via bioretention cells with underdrains. Table 4-2 summarizes the design for each bioretention cell. The bioretention cells are sized to treat site stormwater based on expected pollutant loads in accordance with local stormwater code (City of Edmonds 2010). Due to the low infiltration capacity of the native soil on site, each cell will implement a layer of bioretention soil that removes pollutants by percolation through this layer, but do not rely on infiltration into the subgrade for drainage. An underdrain is included to convey water after it percolates through the treatment layer and routes the flow to the discharge point. Per the recommendation in the Hydrogeologic Report, bioretention cells are designed with only mature, stable compost without biosolids and employ elevated underdrains in order to minimize biofouling of the UIC wells downstream. Table 4-2: Bioretention Cells with Underdrains Summary Sub-Basin 1 Inflow Volume (ac-ft) Treatment Volume (ac-ft) % Total Runoff Treated 1 563.97 549.05 97.35 2 430.56 394.76 91.68 3 51.93 48.41 93.21 4 47.21 45.02 95.37 5A 37.80 37.80 100.00 5B 60.65 58.71 96.81 6 78.51 77.78 99.07 7 96.39 89.23 92.58 8 93.52 85.48 91.41 9 55.64 55.33 99.43 1: See Appendix A Figure A2: Bioretention Drainage Basins Refer to Appendix B for MGS Flood design calculations. CONVEYANCE Runoff is conveyed by a network of swales, gutters, catch basins, manholes, and pipes to the discharge point. Pipes are sized using the Rational Method to convey runoff from the 100-yr event as the site is not designed with overflow connections to city systems. It is the intent that all runoff from the developed area, excluding runoff from 236th St SW, is captured and conveyed to either the groundwater table or the wetland east of the site. Conveyance to each of the UIC wells is designed to encourage sedimentation upstream of the UIC wells. The conveyance network is designed with dead storage in the manifold pipes upstream of the UIC wells to encourage sedimentation prior to discharge to the wells. The pipes connecting the individual UIC wells to the manifold pipes have a negative slope, further encouraging sedimentation in the manifold pipes. This system will ensure that runoff enters the UIC wells in each field uniformly and with the lowest velocity possible (full pipe barrel area utilized). Regular maintenance of the manifold pipes is required to ensure the system KPFF Consulting Engineers 8 performs as intended. See Appendix B for conveyance calculations and Appendix H for maintenance recommendations. 5. Stormwater Pollution Prevention As the proposed development encompasses more than 1-acre, erosion control measures will comply with the requirements of the National Pollution Discharge Elimination System (NPDES) permit administered by the Department of Ecology (DOE). All 12 Stormwater Pollution Prevention (SWPP) elements are to be met. Construction site stormwater best management practices (BMPs) will be implemented as necessary to control erosion and to prevent sediment and other pollutants from leaving the site during construction activities. The SWPP plan demonstrate compliance with these measures and can be found in Appendix G. Madrona School – Edmonds School District Appendix A Appendix A Site Maps · A1: Existing Threshold Discharge Areas · A2: Bioretention Drainage Basins · A3: UIC Well Tributary Areas Madrona School – Edmonds School District Appendix B Appendix B Calculations · B1 - Stormwater Runoff and Pipe Conveyance Calculation · B2 – Flow Splitter Calculation · B3 – Biorention Calculations · B4 – UIC Well Calculations AREA C AREA (SF)Area (AC)(Area (AC)*C)Total Area (AC)Composite C GRASS 0.31 32,888 0.755 0.24 3.103 0.79 PAVEMENT 0.95 102,279 2.348 2.23 TC = 5 (MIN) Hyd. Man. (2-11) Year Storm m =8.75 Hyd. Man. (2-5.4A)Seattle n =0.545 Hyd. Man. (2-5.4A)Seattle I =3.64 (IN/HR)Hyd. Man. (2-4) Flow (Rational) =8.97 (CFS) Storm Drain Profile #100 - SDMH #103 RUNOFF CALCULATIONS (RATIONAL METHOD) 100 \\kpff.com\Civil\1500001-1500400\1500129 (Madrona)\PROJECT DOCUMENTS\Storm Drainage\Calculations\2016-08-22 (CD)\Conveyance\SDPF - 100 - SDMH #103.xlsx Appendix B1 Project Description Friction Method Manning Formula Solve For Full Flow Capacity Input Data Roughness Coefficient 0.010 Channel Slope 0.00500 ft/ft Normal Depth 1.50 ft Diameter 1.50 ft Discharge 9.66 ft³/s Results Discharge 9.66 ft³/s Normal Depth 1.50 ft Flow Area 1.77 ft² Wetted Perimeter 4.71 ft Hydraulic Radius 0.38 ft Top Width 0.00 ft Critical Depth 1.20 ft Percent Full 100.0 % Critical Slope 0.00524 ft/ft Velocity 5.46 ft/s Velocity Head 0.46 ft Specific Energy 1.96 ft Froude Number 0.00 Maximum Discharge 10.39 ft³/s Discharge Full 9.66 ft³/s Slope Full 0.00500 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Worksheet for SDPF 100 - SDAD #103 (18") 12/4/2016 3:15:58 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page > 8.97 CFS ü Appendix B1 GVF Output Data Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 1.50 ft Critical Depth 1.20 ft Channel Slope 0.00500 ft/ft Critical Slope 0.00524 ft/ft Worksheet for SDPF 100 - SDAD #103 (18") 12/4/2016 3:15:58 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page Appendix B1 AREA C AREA (SF)Area (AC)(Area (AC)*C)Total Area (AC)Composite C GRASS 0.31 7,884 0.181 0.06 1.459 0.87 PAVEMENT 0.95 55,670 1.278 1.21 TC = 5 (MIN) Hyd. Man. (2-11) Year Storm m =8.75 Hyd. Man. (2-5.4A)Seattle n =0.545 Hyd. Man. (2-5.4A)Seattle I =3.64 (IN/HR)Hyd. Man. (2-4) Flow (Rational) =4.62 (CFS) Storm Drain Profile #100 - SDAD #104 RUNOFF CALCULATIONS (RATIONAL METHOD) 100 \\kpff.com\Civil\1500001-1500400\1500129 (Madrona)\PROJECT DOCUMENTS\Storm Drainage\Calculations\2016-08-22 (CD)\Conveyance\SDPF - 100 - SDAD #104.xlsx Appendix B1 Project Description Solve For Headwater Elevation Input Data Discharge 4.62 ft³/s Centroid Elevation 0.00 ft Tailwater Elevation 0.00 ft Discharge Coefficient 0.62 Diameter 1.00 ft Results Headwater Elevation 1.40 ft Headwater Height Above Centroid 1.40 ft Tailwater Height Above Centroid 0.00 ft Flow Area 0.79 ft² Velocity 5.88 ft/s Worksheet for SDPF 100 - SDAD #104 12/4/2016 3:17:14 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 1of1Page SHORT SEGMENT OF 12" DIA PIPE WILL BEHAVE SIMILAR TO A 12" DIA ORIFICE. 1.40' BACKWATER AT THE 100YR EVENT AT SDAD #104 DOES NOT OVERTOP THE RIM.ü Appendix B1 AREA C AREA (SF)Area (AC)(Area (AC)*C)Total Area (AC)Composite C GRASS 0.31 3,006 0.069 0.02 0.738 0.89 PAVEMENT 0.95 29,142 0.669 0.64 TC = 5 (MIN) Hyd. Man. (2-11) Year Storm m =8.75 Hyd. Man. (2-5.4A)Seattle n =0.545 Hyd. Man. (2-5.4A)Seattle I =3.64 (IN/HR)Hyd. Man. (2-4) Flow (Rational) =2.39 (CFS) Storm Drain Profile #100 - SDAD #105 RUNOFF CALCULATIONS (RATIONAL METHOD) 100 \\kpff.com\Civil\1500001-1500400\1500129 (Madrona)\PROJECT DOCUMENTS\Storm Drainage\Calculations\2016-08-22 (CD)\Conveyance\SDPF - 100 - SDAD #105.xlsx Appendix B1 Project Description Friction Method Manning Formula Solve For Full Flow Capacity Input Data Roughness Coefficient 0.010 Channel Slope 0.01140 ft/ft Normal Depth 1.00 ft Diameter 1.00 ft Discharge 4.94 ft³/s Results Discharge 4.94 ft³/s Normal Depth 1.00 ft Flow Area 0.79 ft² Wetted Perimeter 3.14 ft Hydraulic Radius 0.25 ft Top Width 0.00 ft Critical Depth 0.91 ft Percent Full 100.0 % Critical Slope 0.00993 ft/ft Velocity 6.30 ft/s Velocity Head 0.62 ft Specific Energy 1.62 ft Froude Number 0.00 Maximum Discharge 5.32 ft³/s Discharge Full 4.94 ft³/s Slope Full 0.01140 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Worksheet for SDPF 100 - SDAD #105 12/4/2016 3:15:34 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page > 2.39 CFS ü Appendix B1 GVF Output Data Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 1.00 ft Critical Depth 0.91 ft Channel Slope 0.01140 ft/ft Critical Slope 0.00993 ft/ft Worksheet for SDPF 100 - SDAD #105 12/4/2016 3:15:34 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page Appendix B1 AREA C AREA (SF)Area (AC)(Area (AC)*C)Total Area (AC)Composite C GRASS 0.31 25,003 0.574 0.18 1.644 0.73 PAVEMENT 0.95 46,609 1.070 1.02 TC = 5 (MIN) Hyd. Man. (2-11) Year Storm m =8.75 Hyd. Man. (2-5.4A)Seattle n =0.545 Hyd. Man. (2-5.4A)Seattle I =3.64 (IN/HR)Hyd. Man. (2-4) Flow (Rational) =4.35 (CFS) Storm Drain Profile #110 - SDAD #111 RUNOFF CALCULATIONS (RATIONAL METHOD) 100 \\kpff.com\Civil\1500001-1500400\1500129 (Madrona)\PROJECT DOCUMENTS\Storm Drainage\Calculations\2016-08-22 (CD)\Conveyance\SDPF - 110 - SDAD #111.xlsx Appendix B1 Project Description Friction Method Manning Formula Solve For Full Flow Capacity Input Data Roughness Coefficient 0.010 Channel Slope 0.01140 ft/ft Normal Depth 1.00 ft Diameter 1.00 ft Discharge 4.94 ft³/s Results Discharge 4.94 ft³/s Normal Depth 1.00 ft Flow Area 0.79 ft² Wetted Perimeter 3.14 ft Hydraulic Radius 0.25 ft Top Width 0.00 ft Critical Depth 0.91 ft Percent Full 100.0 % Critical Slope 0.00993 ft/ft Velocity 6.30 ft/s Velocity Head 0.62 ft Specific Energy 1.62 ft Froude Number 0.00 Maximum Discharge 5.32 ft³/s Discharge Full 4.94 ft³/s Slope Full 0.01140 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Worksheet for SDPF 110 - SDAD #111 12/4/2016 3:14:57 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page > 4.35 CFS ü Appendix B1 GVF Output Data Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 1.00 ft Critical Depth 0.91 ft Channel Slope 0.01140 ft/ft Critical Slope 0.00993 ft/ft Worksheet for SDPF 110 - SDAD #111 12/4/2016 3:14:57 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page Appendix B1 AREA C AREA (SF)Area (AC)(Area (AC)*C)Total Area (AC)Composite C GRASS 0.31 6,926 0.159 0.05 0.411 0.70 PAVEMENT 0.95 10,977 0.252 0.24 TC = 5 (MIN) Hyd. Man. (2-11) Year Storm m =8.75 Hyd. Man. (2-5.4A)Seattle n =0.545 Hyd. Man. (2-5.4A)Seattle I =3.64 (IN/HR)Hyd. Man. (2-4) Flow (Rational) =1.05 (CFS) Storm Drain Profile #610 - SDCB #612 RUNOFF CALCULATIONS (RATIONAL METHOD) 100 \\kpff.com\Civil\1500001-1500400\1500129 (Madrona)\PROJECT DOCUMENTS\Storm Drainage\Calculations\2016-08-22 (CD)\Conveyance\SDPF - 610 - SDCB #612.xlsx Appendix B1 Project Description Friction Method Manning Formula Solve For Full Flow Capacity Input Data Roughness Coefficient 0.010 Channel Slope 0.00500 ft/ft Normal Depth 1.00 ft Diameter 1.00 ft Discharge 3.27 ft³/s Results Discharge 3.27 ft³/s Normal Depth 1.00 ft Flow Area 0.79 ft² Wetted Perimeter 3.14 ft Hydraulic Radius 0.25 ft Top Width 0.00 ft Critical Depth 0.77 ft Percent Full 100.0 % Critical Slope 0.00559 ft/ft Velocity 4.17 ft/s Velocity Head 0.27 ft Specific Energy 1.27 ft Froude Number 0.00 Maximum Discharge 3.52 ft³/s Discharge Full 3.27 ft³/s Slope Full 0.00500 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Worksheet for SDPF 610 - SDCB #612 12/4/2016 3:16:51 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page > 1.05 CFS ü Appendix B1 GVF Output Data Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 1.00 ft Critical Depth 0.77 ft Channel Slope 0.00500 ft/ft Critical Slope 0.00559 ft/ft Worksheet for SDPF 610 - SDCB #612 12/4/2016 3:16:51 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page Appendix B1 AREA C AREA (SF)Area (AC)(Area (AC)*C)Total Area (AC)Composite C GRASS 0.31 0 0.000 0.00 0.224 0.95 PAVEMENT 0.95 9,742 0.224 0.21 TC = 5 (MIN) Hyd. Man. (2-11) Year Storm m =8.75 Hyd. Man. (2-5.4A)Seattle n =0.545 Hyd. Man. (2-5.4A)Seattle I =3.64 (IN/HR)Hyd. Man. (2-4) Flow (Rational) =0.77 (CFS) Storm Drain Profile #700 - SDCO #701 RUNOFF CALCULATIONS (RATIONAL METHOD) 100 \\kpff.com\Civil\1500001-1500400\1500129 (Madrona)\PROJECT DOCUMENTS\Storm Drainage\Calculations\2016-08-22 (CD)\Conveyance\SDPF - 700 - SDCO #701.xlsx Appendix B1 Project Description Friction Method Manning Formula Solve For Full Flow Capacity Input Data Roughness Coefficient 0.010 Channel Slope 0.00500 ft/ft Normal Depth 0.67 ft Diameter 0.67 ft Discharge 1.13 ft³/s Results Discharge 1.13 ft³/s Normal Depth 0.67 ft Flow Area 0.35 ft² Wetted Perimeter 2.10 ft Hydraulic Radius 0.17 ft Top Width 0.00 ft Critical Depth 0.50 ft Percent Full 100.0 % Critical Slope 0.00601 ft/ft Velocity 3.19 ft/s Velocity Head 0.16 ft Specific Energy 0.83 ft Froude Number 0.00 Maximum Discharge 1.21 ft³/s Discharge Full 1.13 ft³/s Slope Full 0.00500 ft/ft Flow Type SubCritical GVF Input Data Downstream Depth 0.00 ft Length 0.00 ft Number Of Steps 0 GVF Output Data Upstream Depth 0.00 ft Profile Description Profile Headloss 0.00 ft Average End Depth Over Rise 0.00 % Worksheet for SDPF 700 12/4/2016 3:16:25 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of1Page > 0.77 CFS ü Appendix B1 GVF Output Data Normal Depth Over Rise 100.00 % Downstream Velocity Infinity ft/s Upstream Velocity Infinity ft/s Normal Depth 0.67 ft Critical Depth 0.50 ft Channel Slope 0.00500 ft/ft Critical Slope 0.00601 ft/ft Worksheet for SDPF 700 12/4/2016 3:16:25 PM Bentley Systems, Inc. Haestad Methods Solution CenterBentley FlowMaster V8i (SELECTseries 1) [08.11.01.03] 27 Siemons Company Drive Suite 200 W Watertown, CT 06795 USA +1-203-755-1666 2of2Page Appendix B1 Water Quality Flow Rate Orifice Calculations Head Diameter of orifice =2.19 IN Q =0.180 CFS Head above bottom orifice =1.92 FT Appendix B2 ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.38 Program License Number: 200410007 Project Simulation Performed on: 11/28/2016 6:19 PM Report Generation Date: 11/28/2016 6:19 PM ————————————————————————————————— Input File Name: 2016-11-02 Bioretention Cells.fld Project Name: Madrona K-8 Analysis Title: Bioretention Cells Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 12 Full Period of Record Available used for Routing Precipitation Station : 96003605 Puget East 36 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961036 Puget East 36 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 1.000 5.565 Area of Links that Include Precip/Evap (acres) 0.000 0.047 Total (acres) 1.000 5.612 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : Subbasin 1 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.000 Outwash Forest 0.000 Appendix B3 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 1.000 ---------------------------------------------- Subbasin Total 1.000 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 10 ---------- Subbasin : BASIN 1 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 1.747 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.715 ---------------------------------------------- Subbasin Total 2.462 ---------- Subbasin : BASIN 2 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.574 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 1.070 ---------------------------------------------- Subbasin Total 1.644 ---------- Subbasin : BASIN 4 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.023 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Appendix B3 Impervious 0.118 ---------------------------------------------- Subbasin Total 0.141 ---------- Subbasin : BASIN 3 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.021 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.130 ---------------------------------------------- Subbasin Total 0.151 ---------- Subbasin : BASIN 5A ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.013 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.092 ---------------------------------------------- Subbasin Total 0.105 ---------- Subbasin : BASIN 6 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.028 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.196 ---------------------------------------------- Subbasin Total 0.224 ---------- Subbasin : BASIN 7 ---------- -------Area(Acres) -------- Till Forest 0.000 Appendix B3 Till Pasture 0.000 Till Grass 0.020 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.240 ---------------------------------------------- Subbasin Total 0.260 ---------- Subbasin : BASIN 8 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.021 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.233 ---------------------------------------------- Subbasin Total 0.254 ---------- Subbasin : BASIN 9 ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.027 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Impervious 0.128 ---------------------------------------------- Subbasin Total 0.155 ---------- Subbasin : BASIN 5B ---------- -------Area(Acres) -------- Till Forest 0.000 Till Pasture 0.000 Till Grass 0.028 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 1 0.000 Appendix B3 Impervious 0.141 ---------------------------------------------- Subbasin Total 0.169 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 10 ------------------------------------------ Link Name: BioRetCell 1 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 445.76 Riser Crest Elevation (ft) : 446.76 Storage Depth (ft) : 1.00 Bottom Length (ft) : 232.5 Bottom Width (ft) : 2.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 465. Area at Riser Crest El (sq-ft) : 1,908. (acres) : 0.044 Volume at Riser Crest (cu-ft) : 1,459. (ac-ft) : 0.033 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 1.50 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 446.76 ft Hydraulic Structure Geometry Number of Devices: 0 Appendix B3 ------------------------------------------ Link Name: BioRetCell 2 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 443.02 Riser Crest Elevation (ft) : 443.69 Storage Depth (ft) : 0.67 Bottom Length (ft) : 125.0 Bottom Width (ft) : 6.8 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 851. Area at Riser Crest El (sq-ft) : 1,397. (acres) : 0.032 Volume at Riser Crest (cu-ft) : 1,262. (ac-ft) : 0.029 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 1.50 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 443.69 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 3 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 443.39 Riser Crest Elevation (ft) : 443.66 Storage Depth (ft) : 0.27 Bottom Length (ft) : 53.3 Bottom Width (ft) : 1.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 53. Area at Riser Crest El (sq-ft) : 144. (acres) : 0.003 Appendix B3 Volume at Riser Crest (cu-ft) : 58. (ac-ft) : 0.001 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 3.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 443.66 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 4 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 443.38 Riser Crest Elevation (ft) : 443.66 Storage Depth (ft) : 0.28 Bottom Length (ft) : 55.8 Bottom Width (ft) : 1.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 56. Area at Riser Crest El (sq-ft) : 154. (acres) : 0.004 Volume at Riser Crest (cu-ft) : 63. (ac-ft) : 0.001 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 3.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Appendix B3 Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 443.66 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 5A Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 442.95 Riser Crest Elevation (ft) : 443.66 Storage Depth (ft) : 0.71 Bottom Length (ft) : 55.4 Bottom Width (ft) : 3.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 166. Area at Riser Crest El (sq-ft) : 433. (acres) : 0.010 Volume at Riser Crest (cu-ft) : 310. (ac-ft) : 0.007 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 3.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 443.66 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 6 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 442.03 Appendix B3 Riser Crest Elevation (ft) : 442.52 Storage Depth (ft) : 0.49 Bottom Length (ft) : 96.4 Bottom Width (ft) : 1.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 96. Area at Riser Crest El (sq-ft) : 391. (acres) : 0.009 Volume at Riser Crest (cu-ft) : 176. (ac-ft) : 0.004 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 3.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 442.52 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 7 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 442.02 Riser Crest Elevation (ft) : 442.52 Storage Depth (ft) : 0.50 Bottom Length (ft) : 99.5 Bottom Width (ft) : 1.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 100. Area at Riser Crest El (sq-ft) : 410. (acres) : 0.009 Volume at Riser Crest (cu-ft) : 186. (ac-ft) : 0.004 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 1.50 Appendix B3 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 442.52 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 8 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 442.03 Riser Crest Elevation (ft) : 442.52 Storage Depth (ft) : 0.49 Bottom Length (ft) : 91.9 Bottom Width (ft) : 1.0 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 92. Area at Riser Crest El (sq-ft) : 374. (acres) : 0.009 Volume at Riser Crest (cu-ft) : 168. (ac-ft) : 0.004 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 1.50 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 442.52 ft Hydraulic Structure Geometry Number of Devices: 0 Appendix B3 ------------------------------------------ Link Name: BioRetCell 9 Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 441.70 Riser Crest Elevation (ft) : 442.56 Storage Depth (ft) : 0.86 Bottom Length (ft) : 20.0 Bottom Width (ft) : 4.9 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 98. Area at Riser Crest El (sq-ft) : 252. (acres) : 0.006 Volume at Riser Crest (cu-ft) : 205. (ac-ft) : 0.005 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 3.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 442.56 ft Hydraulic Structure Geometry Number of Devices: 0 ------------------------------------------ Link Name: BioRetCell 5B Link Type: Bioretention Facility Downstream Link: None Base Elevation (ft) : 441.73 Riser Crest Elevation (ft) : 442.61 Storage Depth (ft) : 0.88 Bottom Length (ft) : 14.6 Bottom Width (ft) : 3.5 Side Slopes (ft/ft) : L1= 3.00 L2= 3.00 W1= 3.00 W2= 3.00 Bottom Area (sq-ft) : 51. Area at Riser Crest El (sq-ft) : 174. (acres) : 0.004 Appendix B3 Volume at Riser Crest (cu-ft) : 125. (ac-ft) : 0.003 Infiltration on Bottom and Sideslopes Selected Soil Properties Biosoil Thickness (ft) : 1.50 Biosoil Saturated Hydraulic Conductivity (in/hr) : 3.00 Biosoil Porosity (Percent) : 40.00 Maximum Elevation of Bioretention Soil : 450.00 Native Soil Hydraulic Conductivity (in/hr) : 0.00 Underdrain Present Orifice NOT Present in Under Drain Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 12.00 Common Length (ft) : 0.000 Riser Crest Elevation : 442.61 ft Hydraulic Structure Geometry Number of Devices: 0 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 10 Number of Links: 10 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: Subbasin 1 0.000 _____________________________________ Total: 0.000 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: BASIN 1 201.151 Subbasin: BASIN 2 66.091 Subbasin: BASIN 4 2.648 Subbasin: BASIN 3 2.418 Subbasin: BASIN 5A 1.497 Appendix B3 Subbasin: BASIN 6 3.224 Subbasin: BASIN 7 2.303 Subbasin: BASIN 8 2.418 Subbasin: BASIN 9 3.109 Subbasin: BASIN 5B 3.224 Link: BioRetCell 1 0.000 Link: BioRetCell 2 0.000 Link: BioRetCell 3 0.000 Link: BioRetCell 4 0.000 Link: BioRetCell 5A 0.000 Link: BioRetCell 6 0.000 Link: BioRetCell 7 0.000 Link: BioRetCell 8 0.000 Link: BioRetCell 9 0.000 Link: BioRetCell 5B 0.000 _____________________________________ Total: 288.082 Total Predevelopment Recharge is Less than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.000 ac-ft/year, Post Developed: 1.823 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 10 ********** Link: BioRetCell 1 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 557.35 Inflow Volume Including PPT-Evap (ac-ft): 563.97 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 549.05, 97.35% Primary Outflow To Downstream System (ac-ft): 564.35 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 97.35% >91% ********** Link: BioRetCell 2 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 421.87 Inflow Volume Including PPT-Evap (ac-ft): 430.56 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 394.76, 91.68% Primary Outflow To Downstream System (ac-ft): 430.98 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 91.68% >91% Appendix B3 ********** Link: BioRetCell 3 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 51.25 Inflow Volume Including PPT-Evap (ac-ft): 51.93 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 48.41, 93.21% Primary Outflow To Downstream System (ac-ft): 52.00 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 93.21% >91% ********** Link: BioRetCell 4 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 46.52 Inflow Volume Including PPT-Evap (ac-ft): 47.21 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 45.02, 95.37% Primary Outflow To Downstream System (ac-ft): 47.27 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 95.37% >91% ********** Link: BioRetCell 5A ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 36.27 Inflow Volume Including PPT-Evap (ac-ft): 37.80 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 37.80, 100.00% Primary Outflow To Downstream System (ac-ft): 37.87 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 100.00% >91% ********** Link: BioRetCell 6 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 77.28 Inflow Volume Including PPT-Evap (ac-ft): 78.51 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 77.78, 99.07% Primary Outflow To Downstream System (ac-ft): 78.60 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 99.07% >91% ********** Link: BioRetCell 7 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 94.62 Inflow Volume Including PPT-Evap (ac-ft): 96.39 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 89.23, 92.58% Primary Outflow To Downstream System (ac-ft): 96.65 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 92.58% >91% Appendix B3 ********** Link: BioRetCell 8 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 91.86 Inflow Volume Including PPT-Evap (ac-ft): 93.52 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 85.48, 91.41% Primary Outflow To Downstream System (ac-ft): 93.74 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 91.41% >91% ********** Link: BioRetCell 9 ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 54.72 Inflow Volume Including PPT-Evap (ac-ft): 55.64 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 55.33, 99.43% Primary Outflow To Downstream System (ac-ft): 55.66 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 99.43% >91% ********** Link: BioRetCell 5B ********** Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 60.01 Inflow Volume Including PPT-Evap (ac-ft): 60.65 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 58.71, 96.81% Primary Outflow To Downstream System (ac-ft): 60.68 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 96.81% >91% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: Subbasin 1 Scenario Postdeveloped Compliance Link: BioRetCell 9 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 0.354 2-Year 2.757E-02 5-Year 0.471 5-Year 4.930E-02 10-Year 0.557 10-Year 5.884E-02 25-Year 0.668 25-Year 7.324E-02 50-Year 0.857 50-Year 9.416E-02 100-Year 1.021 100-Year 0.107 200-Year 1.097 200-Year 0.141 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Appendix B3 ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.40 Program License Number: 200410007 Project Simulation Performed on: 11/30/2016 4:05 PM Report Generation Date: 11/30/2016 4:06 PM ————————————————————————————————— Input File Name: UIC FIELDS.fld Project Name: MADRONA SCHOOL Analysis Title: UIC WELL SIZING Comments: ANALYSIS TO DETERMINE PEAK FLOWS TO UIC WELL FIELDS 1-HR Time Step, Puget East 36 ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 60 Extended Precipitation Time Series Selected Climatic Region Number: 0 Full Period of Record Available used for Routing Precipitation Station : 96003605 Puget East 36 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961036 Puget East 36 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 1.000 9.582 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 1.000 9.582 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 ---------- Subbasin : NULL ---------- -------Area (Acres) -------- Impervious 1.000 ---------------------------------------------- Subbasin Total 1.000 Appendix B4 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 4 ---------- Subbasin : UIC WELL FIELD #2 ---------- -------Area (Acres) -------- Till Grass 0.914 Impervious 2.169 ---------------------------------------------- Subbasin Total 3.083 ---------- Subbasin : UIC WELL FIELD #3 ---------- -------Area (Acres) -------- Till Grass 0.244 Impervious 1.080 ---------------------------------------------- Subbasin Total 1.324 ---------- Subbasin : UIC WELL FIELD #4 ---------- -------Area (Acres) -------- Till Grass 1.014 Impervious 0.922 ---------------------------------------------- Subbasin Total 1.936 ---------- Subbasin : UIC WELL FIELD #1 ---------- -------Area (Acres) -------- Till Grass 0.876 Impervious 2.363 ---------------------------------------------- Subbasin Total 3.239 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ------------------------------------------ Link Name: OIL WATER SEPARATOR Link Type: Copy Downstream Link: None Appendix B4 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 1 Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 4 Number of Links: 1 ********** Subbasin: UIC WELL FIELD #3 ********** Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.302 5-Year 0.382 10-Year 0.447 25-Year 0.514 50-Year 0.601 100-Year 0.680 200-Year 0.740 ********** Subbasin: UIC WELL FIELD #4 ********** Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.288 5-Year 0.378 10-Year 0.457 25-Year 0.605 50-Year 0.662 100-Year 0.728 200-Year 0.883 ********** Subbasin: UIC WELL FIELD #1 ********** Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.680 5-Year 0.855 10-Year 1.014 25-Year 1.178 50-Year 1.361 100-Year 1.550 200-Year 1.727 Appendix B4 ********** Link: OIL WATER SEPARATOR ********** Link Inflow Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.680 5-Year 0.855 10-Year 1.014 25-Year 1.178 50-Year 1.361 100-Year 1.550 200-Year 1.727 ********** Link: OIL WATER SEPARATOR ********** Link Outflow 1 Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.680 5-Year 0.855 10-Year 1.014 25-Year 1.178 50-Year 1.361 100-Year 1.550 200-Year 1.727 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: NULL 0.000 _____________________________________ Total: 0.000 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: UIC WELL FIELD #2 105.715 Subbasin: UIC WELL FIELD #3 28.222 Subbasin: UIC WELL FIELD #4 117.281 Subbasin: UIC WELL FIELD #1 101.320 Link: OIL WATER SEPARATOR 0.000 _____________________________________ Total: 352.537 Total Predevelopment Recharge is Less than Post Developed Average Recharge Per Year, (Number of Years= 158) Appendix B4 Predeveloped: 0.000 ac-ft/year, Post Developed: 2.231 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 0 ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 ********** Link: OIL WATER SEPARATOR ********** 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91% Exceedance): 0.33 cfs Off-line Design Discharge Rate (91% Exceedance): 0.18 cfs Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 1057.15 Inflow Volume Including PPT-Evap (ac-ft): 1057.15 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 1057.15 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Subbasin: NULL Scenario Postdeveloped Compliance Subbasin: UIC WELL FIELD #2 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 0.268 2-Year 0.625 5-Year 0.340 5-Year 0.790 10-Year 0.398 10-Year 0.944 25-Year 0.447 25-Year 1.106 50-Year 0.526 50-Year 1.265 100-Year 0.589 100-Year 1.443 200-Year 0.615 200-Year 1.619 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Appendix B4 EPASWMM Time Series Data MGSFlood Output, Subbasin Outflow: UIC WELL FIELD #1 - Target Tr= 100 Years, (Actual Plotting Position Tr= 101.4 Years) DAY TIME CFS CFS GPM 6/10/2010 10:00 0.0038 0.00076 0.34 6/10/2010 11:00 0.0028 0.00056 0.25 6/10/2010 12:00 0.0022 0.00044 0.20 6/10/2010 13:00 0.0018 0.00036 0.16 6/10/2010 14:00 0.0015 0.0003 0.13 6/10/2010 15:00 0.0012 0.00024 0.11 6/10/2010 16:00 0.0067 0.00134 0.60 6/10/2010 17:00 1.5536 0.31072 139.46 6/10/2010 18:00 1.0035 0.2007 90.08 6/10/2010 19:00 0.3157 0.06314 28.34 6/10/2010 20:00 0.1302 0.02604 11.69 6/10/2010 21:00 0.0669 0.01338 6.01 6/10/2010 22:00 0.0404 0.00808 3.63 6/10/2010 23:00 0.0276 0.00552 2.48 6/11/2010 0:00 0.0206 0.00412 1.85 6/11/2010 1:00 0.0164 0.00328 1.47 6/11/2010 2:00 0.0138 0.00276 1.24 6/11/2010 3:00 0.012 0.0024 1.08 6/11/2010 4:00 0.0107 0.00214 0.96 6/11/2010 5:00 0.0098 0.00196 0.88 6/11/2010 6:00 0.009 0.0018 0.81 6/11/2010 7:00 0.0084 0.00168 0.75 6/11/2010 8:00 0.0079 0.00158 0.71 6/11/2010 9:00 0.0075 0.0015 0.67 5 UIC WELLS INDIVIDUAL UIC WELL Appendix B4 EPASWMM Time Series Data MGSFlood Output, Subbasin Outflow: UIC WELL FIELD #2 - Target Tr= 100 Years, (Actual Plotting Position Tr= 101.4 Years) DAY TIME CFS CFS GPM 6/10/2010 10:00 0.0035 0.0007 0.31 6/10/2010 11:00 0.0026 0.00052 0.23 6/10/2010 12:00 0.0021 0.00042 0.19 6/10/2010 13:00 0.0017 0.00034 0.15 6/10/2010 14:00 0.0014 0.00028 0.13 6/10/2010 15:00 0.0011 0.00022 0.10 6/10/2010 16:00 0.0061 0.00122 0.55 6/10/2010 17:00 1.4462 0.28924 129.82 6/10/2010 18:00 0.931 0.1862 83.57 6/10/2010 19:00 0.291 0.0582 26.12 6/10/2010 20:00 0.1207 0.02414 10.83 6/10/2010 21:00 0.0626 0.01252 5.62 6/10/2010 22:00 0.0382 0.00764 3.43 6/10/2010 23:00 0.0264 0.00528 2.37 6/11/2010 0:00 0.0199 0.00398 1.79 6/11/2010 1:00 0.0161 0.00322 1.45 6/11/2010 2:00 0.0136 0.00272 1.22 6/11/2010 3:00 0.012 0.0024 1.08 6/11/2010 4:00 0.0108 0.00216 0.97 6/11/2010 5:00 0.0098 0.00196 0.88 6/11/2010 6:00 0.0091 0.00182 0.82 6/11/2010 7:00 0.0086 0.00172 0.77 6/11/2010 8:00 0.0081 0.00162 0.73 6/11/2010 9:00 0.0077 0.00154 0.69 5 UIC WELLS INDIVIDUAL UIC WELL Appendix B4 EPASWMM Time Series Data MGSFlood Output, Subbasin Outflow: UIC WELL FIELD #3 - Target Tr= 100 Years, (Actual Plotting Position Tr= 101.4 Years) DAY TIME CFS CFS GPM 6/10/2010 10:00 0.0018 0.0006 0.27 6/10/2010 11:00 0.0013 0.000433 0.19 6/10/2010 12:00 0.001 0.000333 0.15 6/10/2010 13:00 0.0008 0.000267 0.12 6/10/2010 14:00 0.0007 0.000233 0.10 6/10/2010 15:00 0.0006 0.0002 0.09 6/10/2010 16:00 0.003 0.001 0.45 6/10/2010 17:00 0.6815 0.227167 101.96 6/10/2010 18:00 0.4445 0.148167 66.50 6/10/2010 19:00 0.1426 0.047533 21.33 6/10/2010 20:00 0.0579 0.0193 8.66 6/10/2010 21:00 0.029 0.009667 4.34 6/10/2010 22:00 0.0169 0.005633 2.53 6/10/2010 23:00 0.0111 0.0037 1.66 6/11/2010 0:00 0.0079 0.002633 1.18 6/11/2010 1:00 0.0061 0.002033 0.91 6/11/2010 2:00 0.0049 0.001633 0.73 6/11/2010 3:00 0.0041 0.001367 0.61 6/11/2010 4:00 0.0036 0.0012 0.54 6/11/2010 5:00 0.0032 0.001067 0.48 6/11/2010 6:00 0.0029 0.000967 0.43 6/11/2010 7:00 0.0026 0.000867 0.39 6/11/2010 8:00 0.0025 0.000833 0.37 6/11/2010 9:00 0.0023 0.000767 0.34 3 UIC WELLS INDIVIDUAL UIC WELL Appendix B4 EPASWMM Time Series Data MGSFlood Output, Subbasin Outflow: UIC WELL FIELD #4 - Target Tr= 100 Years, (Actual Plotting Position Tr= 101.4 Years) DAY TIME CFS CFS GPM 6/10/2010 10:00 0.0015 0.0005 0.22 6/10/2010 11:00 0.0011 0.000367 0.16 6/10/2010 12:00 0.0009 0.0003 0.13 6/10/2010 13:00 0.0007 0.000233 0.10 6/10/2010 14:00 0.0006 0.0002 0.09 6/10/2010 15:00 0.0005 0.000167 0.07 6/10/2010 16:00 0.0026 0.000867 0.39 6/10/2010 17:00 0.7292 0.243067 109.10 6/10/2010 18:00 0.4522 0.150733 67.65 6/10/2010 19:00 0.1307 0.043567 19.55 6/10/2010 20:00 0.0579 0.0193 8.66 6/10/2010 21:00 0.033 0.011 4.94 6/10/2010 22:00 0.0225 0.0075 3.37 6/10/2010 23:00 0.0172 0.005733 2.57 6/11/2010 0:00 0.0143 0.004767 2.14 6/11/2010 1:00 0.0125 0.004167 1.87 6/11/2010 2:00 0.0113 0.003767 1.69 6/11/2010 3:00 0.0105 0.0035 1.57 6/11/2010 4:00 0.0098 0.003267 1.47 6/11/2010 5:00 0.0093 0.0031 1.39 6/11/2010 6:00 0.0088 0.002933 1.32 6/11/2010 7:00 0.0084 0.0028 1.26 6/11/2010 8:00 0.0081 0.0027 1.21 6/11/2010 9:00 0.0078 0.0026 1.17 3 UIC WELLS INDIVIDUAL UIC WELL Appendix B4 Madrona School – Edmonds School District Appendix C Appendix C Geotechnical Engineering Report By: Shannon & Wilson, Inc. Date: October 31, 2016 Geotechnical Engineering Report New Madrona K-8 Project 9300 236th Street SW Edmonds, Washington October 31, 2016 Submitted To: Ms. Taine Wilton Edmonds School District #15 20420 68th Avenue West Lynnwood, Washington 98036 By: Shannon & Wilson, Inc. 400 N 34th Street, Suite 100 Seattle, Washington 98103 21-1-22082-004 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 i TABLE OF CONTENTS Page 1.0 SITE AND PROJECT DESCRIPTION .................................................................................1 2.0 SITE CONDITIONS ..............................................................................................................2 2.1 Regional Geology .......................................................................................................2 2.2 Regional Seismicity ....................................................................................................2 3.0 SUBSURFACE EXPLORATION .........................................................................................3 4.0 FIELD INFILTRATION TESTING ......................................................................................4 5.0 LABORATORY TESTING ...................................................................................................5 6.0 SUBSURFACE CONDITIONS .............................................................................................5 6.1 Site Geology and Subsurface Conditions ...................................................................5 6.1.1 Subsurface Conditions at Proposed Building ..............................................5 6.1.2 Subsurface Conditions at Proposed Parking Lots and Driveways ...............6 6.2 Hydrogeologic Conditions .........................................................................................6 7.0 ENGINEERING STUDIES AND RECOMMENDATIONS ................................................6 7.1 General .......................................................................................................................6 7.2 Foundation Design .....................................................................................................7 7.3 Seismic Design ...........................................................................................................7 7.4 Lateral Earth Pressures and Retaining Walls .............................................................8 7.5 Lateral Resistance ......................................................................................................9 7.6 Slope Stability ............................................................................................................9 7.7 Pavement Design ......................................................................................................10 7.7.1 Traffic Load ...............................................................................................10 7.7.2 Subgrade Conditions ..................................................................................10 7.8 Non-Porous Pavement Section Recommendations ..................................................10 7.9 Porous Pavement Section Recommendations ..........................................................11 7.9.1 Grass Grid Pavers ......................................................................................11 7.9.2 Pervious Hot Mix Asphalt (HMA) and Concrete ......................................11 7.10 Pavement Sections Near Steep Slopes .....................................................................12 7.11 Frost Susceptibility ...................................................................................................12 8.0 GEOTECHNICAL CONSTRUCTION RECOMMENDATIONS .....................................13 8.1 Earthwork and Use of On-site Soils .........................................................................13 8.2 Pervious Pavement Materials ...................................................................................14 8.3 Construction and Maintenance Considerations for Pervious Pavement ..................14 8.4 Temporary and Permanent Excavation Slopes .........................................................15 8.5 Erosion Control ........................................................................................................16 TABLE OF CONTENTS (cont.) Page 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 ii 8.6 Construction Drainage ..............................................................................................16 8.7 Subsurface Drainage ................................................................................................16 8.8 Utilities .....................................................................................................................16 8.9 Wet Weather Earthwork ...........................................................................................17 8.10 Plans Review and Construction Observation ...........................................................18 9.0 LIMITATIONS ....................................................................................................................18 10.0 REFERENCES .....................................................................................................................20 TABLES 1 Recommended Minimum Parking Lot and Driveway Section Thicknesses .........11 2 Recommended Minimum Porous Pavement Section Thicknesses ........................11 3 Imported Backfill Specifications Based on 2016 Washington State Department of Transportation Standard Specifications .........................................13 FIGURES 1 Vicinity Map 2 Site and Exploration Plan 3 Typical Rockery Detail 4 Measured Water Level, Pilot Infiltration Test, Test Pit PIT-1 5 Measured Water Level, Pilot Infiltration Test, Test Pit PIT-2 6 Measured Water Level, Pilot Infiltration Test, Test Pit PIT-3 APPENDICES A Subsurface Explorations B Laboratory Test Results C Analytical Laboratory Test Results D Important Information About Your Geotechnical/Environmental Report 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 1 GEOTECHNICAL ENGINEERING REPORT NEW MADRONA K-8 PROJECT 9300 236TH STREET SW EDMONDS, WASHINGTON 1.0 SITE AND PROJECT DESCRIPTION The Edmonds School District No. 15 plans to construct a new Madrona K-8 School on the south side of the property at 9300 236th Street SW in Edmonds, Washington, as shown in the Vicinity Map (Figure 1). The property contains the existing Madrona K-8 School and is bounded by 236th Street to the north, residential developments on the east and south sides, and the former Woodway Elementary School on the west. The site has a number of distinct surface features including a parking lot on the northwest side, track and large open field area on the southwest side, and a baseball field on the southeast side. There is a densely wooded ravine area along the east side of the property and a densely wooded slope on the west side of the property that slopes down to the former Woodway Elementary School. The purpose of this study is to finalize our geotechnical recommendations with data from additional subsurface explorations and testing to aid in the final design of the proposed structure. Geotechnical recommendations were provided previously in a preliminary geotechnical engineering report submitted on August 6, 2015. Our scope of services for the design phase included drilling and sampling 12 geotechnical borings and excavating 5 test pits. However, one of the proposed drilling locations was changed to a test pit exploration for a total of 11 geotechnical borings and 6 test pits. The proposed drilling location was changed to a test pit due to the close proximity to subsurface utilities and access issues. Locations of the subsurface explorations were selected to coincide with the planned location of the proposed building and associated facilities. Descriptions of the subsurface exploration activities are discussed further in Section 3.0. The results of our pilot infiltration testing (PIT) are discussed in Section 4.0. This report presents updated geotechnical engineering recommendations to incorporate the additional subsurface information gathered from the new explorations and information provided by the design team. We have included recommendations for pavement design and a discussion of buffer and setback distances when adjacent to steep slopes and other geologic hazard areas. The results of the soil fertility testing are also provided to aid the design team in evaluating the suitability of on-site topsoil for use in landscaping. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 2 2.0 SITE CONDITIONS 2.1 Regional Geology The site is located in Edmonds, Washington, which is within a region known as the Puget Lowland. The Puget Lowland is a structural depression bordered by the Olympic and Cascade Mountain ranges that is generally within about 500 feet of sea level. The geology of the area has been influenced by repeated cycles of glaciation, which worked to fill the lowland to significant depths with a complex sequence of glacial and nonglacial deposits. The most recent glacier to impact the area, the Vashon Stade of the Fraser Glaciation, overrode the area with up to 3,000 feet of ice in some locations. Following the last glaciations, the erosion of some of the glacially overridden soil deposits, as well as local deposition and human placement of additional soil deposits, have further complicated the local geology (Troost and Booth, 2008). The project site itself is situated on a ridge underlain by Quaternary Vashon till (Qvt) that was observed at relatively shallow depths during the current subsurface investigation. This geologic unit was found to be a very dense, gray to gray-brown deposit consisting of silty sand with variable gravel, cobble, and some boulder content. Other explorations performed on the site (Shannon & Wilson, Inc. [Shannon & Wilson], 2016) encountered deposits of Quaternary Vashon advanced glacial outwash (Qva) at depths of approximately 40 to 50 feet below ground surface (bgs). This geologic unit is characterized by dense to very dense sands and gravels with variable amounts of silt. Qva is typically less compact and more pervious than Qvt. Geologic maps of the Snohomish County region indicate that the contact between the glacial till and advanced outwash material is on the slope on the west side of the property. The Qva at the site may be underlain by pre-Vashon interglacial and glacial soils, predominantly fluvial. 2.2 Regional Seismicity The Puget Sound Lowland is located in the fore arc of the Cascadia Subduction Zone. The seismicity of the region is largely derived from the subduction of the Juan de Fuca Plate beneath the North American Plate. The convergence of these two plates results in a number of generally east-west-trending faults, as well as basin and uplift regions (Troost and Booth, 2008). The seismic hazard of the region comes from three major sources, a major subduction type events, deep intraplate events (such as the 2001 Nisqually earthquake), and earthquakes due to rupture of shallow crustal faults. The site itself is located a reasonable distance from subduction and intraslab sources, and as a result, the more local, crustal faults are believed to drive the seismic hazard for the site. The closest known potentially active fault to the site is the South Whidbey Island Fault (SWIF). The 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 3 SWIF is a shallow, strike-slip fault that is believed to be capable of producing a magnitude 7.5 event, which could impose significant seismic demands on structures at the site. 3.0 SUBSURFACE EXPLORATION Previously, we completed subsurface explorations as a part of a preliminary geotechnical engineering study to aid in the selection of the proposed building location. Previous explorations consisting of 16 test pits on the southern half of the property were completed on June 24, 2015. Logs of the previous subsurface explorations are included in Appendix A. Recent subsurface explorations consisted of test pits and geotechnical borings completed between Monday, July 25, 2016, and Friday, July 29, 2016. Holocene Drilling (Holocene), under subcontract to Shannon & Wilson, completed a total of 11 geotechnical borings with the use of a track-mounted Diedrich D-50 drill rig. Holocene used the hollow-stem auger drilling method to complete the borings to depths ranging from 15.5 to 16.5 feet bgs. Holocene collected samples on approximate 2.5-foot intervals with the use of the Standard Penetration Test. Once the geotechnical borings were completed, Holocene backfilled the holes with bentonite to within approximately 1 to 2 feet bgs. Borings that were drilled in the asphalt parking area were patched with concrete. Clearcreek Contractors (Clearcreek), under subcontract to Shannon & Wilson, completed a total of six test pits to depths ranging from 4 to 10 feet with the use of a rubber-tired John Deere 310SJ backhoe. Three of the test pits were used to characterize infiltration within the near- surface soils. Infiltration testing within the near-surface soils is discussed below in Section 4.0. Following the excavations and testing, Clearcreek backfilled the test pits with the excavated material and tamped the material down using the excavator bucket in approximately 1-foot-thick lifts. Once Clearcreek had completed backfilling the test pits, they rolled the surface for further compaction and replaced the grass layer where it was possible to salvage. The explorations were located throughout the site as shown in the Site and Exploration Plan, Figure 2. Test pits designated with a PIT were the ones in which we performed the in situ infiltration testing/PITs, while the test pits designated with a TP were not used for in situ infiltration testing. During the exploration process, the soil and groundwater conditions were observed by an engineer or a geologist from our office. Soil samples were collected and transported to our Seattle laboratory for analysis and testing. Logs of the explorations are presented in Appendix A. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 4 The geotechnical boring and test pit locations provided in Figure 2 are approximate, being based on hand measurements from site features, and surface elevations shown in the logs are estimated from a topographic survey of the site prepared by PACE Engineers, Inc. 4.0 FIELD INFILTRATION TESTING We performed small-scale PITs within three of the six test pits excavated during the current subsurface explorations. The PIT test pits were designated as PIT-1 through PIT-3, and the locations are shown in the Site and Exploration Plan, Figure 2. All three of the infiltration tests were performed on July 28, 2016. These test pits were over excavated following the PITs on July 29, 2016. Details of the three tests are presented below and are summarized in the PIT data plots (Figures 4 through 6). The PIT-1 test pit bottom during the PIT was approximately 3.8 feet bgs, or about Elevation 440.7 feet. The tested soil unit was fill, consisting of reworked glacial till. After the water flow was terminated, the test pit drained completely overnight. No free water was present below the PIT test depth when we overexcavated it on July 29, 2016. A plot of the PIT-1 test data is presented as Figure 4. The observed (short-term) infiltration rate was approximately 0.80 inch per hour, based on the last hour of the constant head period. If these soils represented the subgrade beneath a bioretention feature constructed with imported bioretention soil, the City of Edmonds (City) will require the application of a correction factor of 2 due to the test being performed during the dry season. This would result in a design (long-term) infiltration rate of 0.4 inch per hour. The PIT-2 test pit bottom during the PIT was approximately 3.3 feet bgs, or about Elevation 452.7 feet. The tested soil unit was glacial till, with a short-term infiltration rate of 0.13 inch per hour, based on the falling head data collected after the water flow into the test pit was terminated. Applying the correction factor would result in a design infiltration of 0.06 inch per hour. The test pit failed to drain completely overnight and this soil is considered to be a hydraulic restriction to infiltration, due to its low infiltration rate. A plot of the PIT-2 test data is presented as Figure 5. The PIT-3 test pit bottom during the PIT was approximately 2.9 feet bgs, or about Elevation 447.1 feet. The tested soil unit was glacial till, with a short-term infiltration rate of 0.07 inch per hour based on the falling head data collected after the water flow into the test pit was terminated. Applying the correction factor would result in a design infiltration rate of 0.03 inch per hour. The test pit failed to drain completely overnight and this soil is considered to be a hydraulic 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 5 restriction to infiltration due to its low infiltration rate. A plot of the PIT-3 test data is presented as Figure 6. If a shallow well were installed in the vicinity and read during the wet season, no correction factor would be required, provided groundwater is at least 3 feet below the bottom of the facility. 5.0 LABORATORY TESTING Laboratory testing was conducted on several soil samples collected from the test pit explorations to assist in classification and characterization of the subsurface soils. The laboratory tests included natural moisture content determination and grain size analysis. The natural moisture contents are indicated on the test pit logs in Appendix A. The results of the grain size analyses are presented in Appendix B. Most of the grain size tests were sieve analyses. Combined sieve and hydrometer tests were performed on two samples (from B-4 at 5 feet deep [about Elevation 440 feet] and from B-5 at 7.5 feet deep [about Elevation 439.5 feet]) so that the U.S. Department of Agriculture (USDA) texture could be identified. Both samples are considered to be “sandy loam,” based on the USDA textural system. Based on our discussions with the City, the short-term infiltration rate for these soils is 1 inch per hour. Since the explorations were completed during the dry season, a seasonal correction factor of 2 is required, resulting in a design infiltration rate of 0.5 inch per hour. This assumes that these soils represent the subgrade beneath bioretention features with imported bioretention soil. In order to characterize the existing topsoil within the upper and lower field, we submitted two samples to Spectra Laboratories (Spectra) in Poulsbo, Washington. The samples were tested for soil fertility and the results with recommendations from Spectra are included in Appendix C. 6.0 SUBSURFACE CONDITIONS 6.1 Site Geology and Subsurface Conditions Intact glacial till soils were encountered in all but one of the explorations performed under the current scope of work. The test pit PIT-1 did not encounter intact glacial till, but did encounter weathered till at a depth of approximately 7 feet bgs. 6.1.1 Subsurface Conditions at Proposed Building Explorations performed within or near the proposed building footprint on the existing upper play field in the southeast corner of the site indicate that this area is underlain by a thin layer of topsoil followed by layers of fill, weathered or reworked glacial till, and intact glacial 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 6 till. Borings B-7, B-9, B-10, and B-12 indicate that there is a layer of fill soils at depths ranging from 4.5 to 7 feet bgs. Fill soils consisted of medium dense to very dense, silty sand to silty sand with gravel. Intact very dense glacial till underlying the building footprint was encountered at depths ranging from approximately 1 to 7 feet bgs. 6.1.2 Subsurface Conditions at Proposed Parking Lots and Driveways Explorations performed within the parking areas west of the existing school building and north of the track indicated that fill soils overlying the glacial till are present at depths ranging from 7 to 9.5 feet bgs. Borings and test pits on the north and east sides of the existing building also encountered fill soils at depths ranging from 4.5 to 6 feet bgs. Intact, very dense glacial till was found to underlie the fill soils. 6.2 Hydrogeologic Conditions Groundwater was not encountered in the recent shallow soil borings and test pits, all of which were performed during the dry season. Moist to wet layers were observed below about 15 feet in borings B-2, B-3, and B-5, and below about 12 feet in boring B-9, which may indicate the presence of perched groundwater. Subsurface explorations performed previously onsite as part of our hydrogeologic study (Shannon & Wilson, 2016) identified a regional groundwater aquifer at the site at about 180 feet deep and between approximate Elevations 276.3 to 277.2 feet. Perched groundwater zones were also encountered during the previous hydrogeologic explorations at depths ranging from 8.5 to 11 feet bgs (Shannon & Wilson, 2016). Note that groundwater is not expected to be encountered during excavations for the new school building. We understand that the project stormwater management system will consist of a series of shallow bioretention swales combined with underground injection control (UIC) wells. The results of our recent hydrogeological testing and analysis are presented in a separate report (Shannon & Wilson, 2016). Please refer to this report for design recommendations regarding UIC construction and infiltration rates. 7.0 ENGINEERING STUDIES AND RECOMMENDATIONS 7.1 General Based on the observations made during the subsurface exploration program and information reviewed for the project, we expect the glacial till material will provide good support for conventional spread footing foundations with minimal settlements. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 7 The following subsections provide detailed recommendations on the following topics:  Foundation design  Seismic design  Lateral earth pressures  Lateral resistance  Slope stability  Pavement design 7.2 Foundation Design The subsurface explorations encountered undisturbed, very dense, native glacial till soils across the entire site. Spread footings founded in the dense, native till material may be designed with an allowable bearing pressure of 10,000 pounds per square foot (psf). Spread footings that are founded in compacted structural backfill placed above the glacial till may be designed for an allowable bearing capacity of 4,000 psf. These allowable bearing values may be increased by one-third for transient seismic loading. Any fill material that is to be reused should be evaluated by a geotechnical engineer to see if they are suitable for use. Use of on-site fill material is discussed in Section 8.1. Based on the subsurface conditions, isolated overexcavation could be required due to the presence of some existing fill within the building footprints. As an alternative to overexcavation of fill material encountered at footing subgrade elevations, in situ densification of the fill could be accomplished with the use of heavy vibratory compaction equipment (i.e., excavator-mounted “ho-pac”). Footing subgrades should be observed by a qualified geotechnical engineer or geologist. If the native glacial till material or compacted structural backfill is used as the foundation bearing soils, it is anticipated that any settlement that occurs will be essentially instantaneous as the load is applied during construction. If the footings are designed for the bearing pressures noted above, then the total footing settlements will be less than ½ inch. Differential settlements would be about one-half of the total settlement. However, if the entire structure is founded on the glacial till, then differential settlements would be insignificant. 7.3 Seismic Design The seismic design of the structure should be in accordance with the International Code Council, Inc. 2015 International Building Code (IBC) (International Code Council, Inc., 2014). The IBC design criteria are based on a target risk of structural collapse of 1 percent in 50 years. The soil 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 8 profile is assessed by assigning a site class definition. It is our opinion that based on the soil classification, i.e., very dense, the site can be classified as Site Class C. Seismic inputs are the short-period maximum spectra acceleration, SS, and spectral acceleration at a period of one second, S1. Using the map provided in the IBC, which corresponds to Site Class B sites, the mapped values of SS and S1 are approximately 1.262 and 0.493g, respectively. The site coefficients for the given spectral acceleration values and site class C are 1.0 and 1.31 for Fa and Fv, respectively. Seismic hazards such as liquefaction and fault rupture are not present at the project site. 7.4 Lateral Earth Pressures and Retaining Walls Lateral earth pressures will act on portions of the building as well as on retaining walls. The magnitude and distribution of these lateral pressures will depend on many factors, including, but not limited to, the type of backfill, the method of backfill placement, level of backfill compaction, slope of backfill, drainage, and characteristics of the wall itself. If the wall is allowed to move at least 0.001 times the wall height, the wall is considered flexible and active earth pressures can be used. If the wall is considered to be inflexible then at-rest earth pressures must be used. The active and at-rest earth pressures, evaluated using an equivalent fluid unit weight, are estimated to be on the order of 30 and 50 pounds per cubic feet (pcf), respectively. The values given above assume a permanent wall structure, the ground surface behind the wall is level, and that proper drainage is installed to prevent the buildup of pore water pressure behind the wall. The total earth pressures should be analyzed for seismic loading conditions using a dynamic load increment equal to a percentage of the static earth force. The percentage load increase for seismic condition was developed to be consistent with a pseudo-static analysis using the Mononobe-Okabe equation for lateral earth pressures (Kramer, 1996) and a horizontal seismic coefficient of 0.2. The load increase for seismic conditions is recommended to be a uniformly distributed load equal to 8H, where H is the height of the wall. Note the seismic coefficient is not equal to the peak ground acceleration (PGA) expected to be encountered at the site in a design event. The PGA is experienced only a few times within the record of earthquake shaking, and the actual earthquake ground motion is cyclic in nature, not static. Values of the seismic coefficient are thus typically one-third to one-half the value of the PGA that may be experienced at the site during a design level event. We understand that rockery walls may be installed. Rock walls have been used in numerous locations around Puget Sound area primarily to provide erosion protection to cuts in stable 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 9 materials. Rockeries have also been used to retain fill slopes; however, this practice is not as prevalent. In our opinion, rockeries could be used to retain cut slopes made in dense to very dense native soil that are less than 6 feet high. Rockeries should be constructed in accordance with the recommendations shown in Figure 3. Rockeries could be used to retain fill slopes provided they are 5 feet high or less, or if they are reinforced. If used with a reinforced slope, the rockery would form a façade or erosion protection facing on an otherwise stable slope. Rockeries that are used to retain fill slopes that are 5 feet high or less should be built in accordance with the recommendations shown in Figure 3. We recommend that the fill be built out beyond the planned wall location and then cut back. With this procedure, the fill can be fully compacted, as compared with the difficulty of compacting the edge of a fill slope. 7.5 Lateral Resistance Footings may resist lateral loads using a combination of base friction and passive pressure against the buried or embedded portion of the footings and buried wall. We recommend that base sliding resistance be determined using an allowable coefficient of friction of 0.7 for a concrete foundation founded on on-site glacial till or compacted structural fill. Passive earth pressures can be evaluated using an equivalent unit weight of 400 pcf. This value includes a factor of safety of 1.5. 7.6 Slope Stability The slope along the eastern perimeter of the property is mapped as a critical area by the City due to the steepness of the slope and the presence of wetlands. We recommend that the Madrona K-8 school footprint be set back at least 10 feet from the top of slope. While we did not observe active landsliding on this slope, the Edmonds Community Development Code requires that buildings or other structures constructed near an environmentally critical area maintain a setback of 15 feet from the edge of the critical area which in this case is the top of the slope (Edmonds, Wash., 2016). However, the code also allows for setbacks to be determined by a Geotechnical Engineering Report. In our opinion, after review of the subsurface conditions and the current condition of the slope, a setback of 10 feet would not cause an increased potential for landslides or surficial soil instability on the steep slope. In our opinion, buried utilities within this setback distance are acceptable and will not be at risk due to slope instability. We understand that dead or diseased tree removal is planned along the east, west, and south perimeter of the property near the top of the slopes. We made a site visit on September 20, 2016, 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 10 to observe the slope areas where tree removal is planned. In our opinion, the planned tree removal will not cause instability of the slope and the trees may be felled and chipped in-place. 7.7 Pavement Design Pavement analyses were conducted using the American Association of State Highway and Transportation Officials (AASHTO) method for flexible and rigid pavement design (AASHTO, 1993). The AASHTO method is a widely used empirical design procedure for the design of flexible and rigid pavement structures. It considers strength of the base course materials, traffic stresses, and the strength of the pavement subgrade. The pavement design life is assumed to be 20 years. 7.7.1 Traffic Load Average daily traffic counts, including delivery trucks, school buses, and occasional heavy vehicles such as fire trucks, were based on assumed conditions for similar projects. Assumed traffic volumes were then converted into equivalent single-axle loads by using equivalent load factors. We assume that there will not be a significant increase in traffic at this location, but did include a 1 percent growth factor in the design life traffic counts for our analysis. 7.7.2 Subgrade Conditions The subgrade conditions at the proposed pavement locations are medium dense, silty sand to silty sand with gravel fill suitable for pavement support. If loose or soft subgrade is observed during construction, we recommend that it be removed and replaced with at least 1 foot of compacted structural fill. A Resilient Modulus, MR, of 15,000 pounds per square inch is recommended for pavement design where existing medium dense fill and newly placed compacted structural fill are present. 7.8 Non-Porous Pavement Section Recommendations For support of the proposed parking and driveway areas we propose pavement section thicknesses shown in Table 1 below. Recommendations have been separated into lightly loaded and heavily loaded pavement sections. Lightly loaded pavement sections are assumed to be those that are utilized primarily by car and other passenger vehicle traffic. Heavily loaded pavement sections are assumed to be those that are utilized by heavy vehicles such as buses, delivery, and fire trucks. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 11 TABLE 1 RECOMMENDED MINIMUM PARKING LOT AND DRIVEWAY SECTION THICKNESSES Pavement Type Pavement Layer Light Loading Heavy Loading Flexible Asphalt 3 inches 4 inches Base Course 4 inches 6 inches Rigid Concrete 4 inches 6 inches Base Course 4 inches 4 inches Base course should correspond to crushed surfacing in accordance with the Washington State Department of Transportation (WSDOT) Standard Specifications (WSDOT, 2016). Placement, compaction, and material specification for crushed surfacing is discussed in Section 8.1 of this report. 7.9 Porous Pavement Section Recommendations 7.9.1 Grass Grid Pavers Grass grid pavers will be a proprietary product and should be designed in accordance with the manufacturer’s recommendations. For design of the porous pavement sections, we recommend that the compacted subgrade be assumed to have a California Bearing Ratio of approximately 20. 7.9.2 Pervious Hot Mix Asphalt (HMA) and Concrete As we understand, porous pavement sections consisting of pervious HMA or concrete underlain by an underdrain are being considered within the fire lane to collect surface drainage. Pervious pavement consists of porous asphalt or concrete overlying a stone bed. For support of the proposed fire lane areas, we propose porous pavement section thicknesses shown in Table 2 below. TABLE 2 RECOMMENDED MINIMUM POROUS PAVEMENT SECTION THICKNESSES Pavement Type Pavement Layer Thickness Pervious HMA Porous Asphalt 5 inches Stone Bed 10 inches Rigid Porous Concrete 9 inches Stone Bed 12 inches 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 12 Please note that porous asphalt is susceptible to considerable wear due to heavy vehicle loading especially in vehicle turning areas. Rutting due to surface abrasion is known to occur between the wheel and the pavement during breaking and turning. Also note that pervious concrete pavement is sensitive to the means and methods used in mix design and placement. We recommend following the American Concrete Institute (ACI) Specification for Pervious Concrete Pavement, ACI 522.1-13 for design and installation practices of porous concrete pavement systems (ACI, 2013). This specification covers materials, preparation, forming, placing, finishing, jointing, curing, and quality control of pervious concrete pavement. Provisions governing testing, evaluation, and acceptance of pervious concrete pavement are included. Pervious concrete pavement will require annual cleaning to maintain its infiltration function. We recommend vacuum cleaning once or twice a year (depending on conditions) with a regenerative sweeper and pressure washing as needed. 7.10 Pavement Sections Near Steep Slopes Pavements constructed near the steep slopes on the east and west perimeters of the property should have the same minimum pavement sections shown above in Table 1. Subsurface conditions encountered in the explorations indicate that the site is underlain by glacial till at relatively shallow depths, so slope stability is not an issue with regard to pavement construction. 7.11 Frost Susceptibility Frost-susceptible soil is regarded as having greater than 3 percent finer that 0.02 millimeter (mm). Soil with a fines content not exceeding 7 percent passing the No. 200 sieve, based on the minus ¾-inch fraction, can normally be expected to have 3 percent or less finer than 0.02 mm. The current subsurface explorations indicate the subgrade soil has an average fines content of about 30 percent, which should be considered frost-susceptible. The measured frost depth during cold winters of 1949 and 1950 was about 15 inches near Edmonds, Washington. In accordance with the WSDOT Pavement Policy (WSDOT, 2015), pavement can be designed for frost protection by providing a pavement section that is equal to or thicker than half of the anticipated frost depth. The pavement section includes pavement and non-frost susceptible base course. In our opinion, the minimum recommended pavement sections presented in Table 1 above should provide adequate frost protection. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 13 8.0 GEOTECHNICAL CONSTRUCTION RECOMMENDATIONS 8.1 Earthwork and Use of On-site Soils Fill placed beneath structures such as floor slabs, pavements, sidewalks, or backfill against footings should be structural fill. Structural fill should be placed and compacted upon native soil surfaces observed during construction by a geotechnical engineer or the engineer’s representative. The fill soils encountered onsite generally contain sufficient fines to make them moisture-sensitive. In our opinion, on-site soils may be difficult to place and compact to adequate relative compaction levels, particularly during wet weather or in wet conditions. The on-site glacial till soils may be used as structural fill material provided the following conditions are met:  The soil is free from organics, debris, or other deleterious material.  The water content of the on-site soil at the time of compaction is close to its optimum as determined by a Modified Proctor Test (ASTM International [ASTM], 2012).  On-site soils used for fills and backfills that become wet and unstable after placement should be removed and replaced with suitable material.  Stockpiled on-site soils are protected when rainfall is anticipated in accordance with Section 2-09.3(1)E (WSDOT, 2016). If on-site soil becomes too difficult to compact or construction site space limitations prevent stockpiling, we recommend using imported, granular, structural backfill. Imported backfill should meet gradation requirements of the WSDOT Standard Specifications (WSDOT, 2016). Table 3 provides material specifications for various backfill applications. On-site soil not suitable for structural backfill could be used as backfill within landscaped areas. TABLE 3 IMPORTED BACKFILL SPECIFICATIONS BASED ON 2016 WASHINGTON STATE DEPARTMENT OF TRANSPORTATION STANDARD SPECIFICATIONS Application Material Specification Structural Fill 9-03.14(1) Gravel Backfill for Walls 9-03.12(2) Gravel Backfill for Pipe Zone Bedding 9-03.12(3) Crushed Surfacing Base Course 9-03.9(3) Structural fill should be placed in horizontal, uniform lifts and compacted to a dense and unyielding condition, and to at least 95 percent of the Modified Proctor maximum dry density (ASTM D1557 [ASTM, 2012]). Subgrades to receive structural fill should be dense and unyielding and should be evaluated by the geotechnical engineer prior to the placement of fill. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 14 Preparation of subgrades should be in accordance with Section 2-06 of the WSDOT Standard Specifications (WSDOT, 2016). In general, the thickness of soil layers before compaction should not exceed 10 inches for heavy equipment compactors or 6 inches for hand-operated mechanical compactors. The most appropriate lift thickness should be determined in the field using the Contractor’s selected equipment and fill, and verified with in situ soil density testing (nuclear gauge methods). All compacted surfaces should be sloped to drain to prevent ponding. Structural fill placement operations should be observed and evaluated by an experienced geotechnical engineer or technician. 8.2 Pervious Pavement Materials We recommend the following material specifications for pervious pavement:  Porous Bituminous Asphalt. The bituminous surface course shall be a bituminous mix of 6 percent by weight dry aggregate. Porous asphalt uses the same mixing and application equipment as for conventional asphalt. A neat asphalt binder modified with an elastomeric polymer is recommended. The polymer modified asphalt binder shall be heat and storage stable. Aggregate shall be minimum 90 percent crushed material and have a recommended gradation of: U.S. Standard Sieve Size Percent Passing ½ (12.5 millimeter [mm]) 100 ⅜ (9.5 mm) 92 to 98 4 (4.75 mm) 34 to 40 8 (2.36 mm) 14 to 20 16 (1.18 mm) 7 to 13 30 (0.60 mm) 0 to 4 200 (0.075 mm) 0 to 2  Stone Bed. Stone bed course aggregate shall be a crushed, ⅜- to 1-inch uniformly graded coarse aggregate conforming to AASHTO size number 67 (or equivalent). Stone bed aggregate shall be placed immediately after approval of subgrade preparation. Clean (washed) stone bed aggregate should be in maximum 8-inch lifts. Each layer shall be compacted to a dense condition with a smooth drum roller. 8.3 Construction and Maintenance Considerations for Pervious Pavement Pervious pavement is susceptible to damage and clogging during construction and afterward. We recommend that the construction be undertaken in such a way as to prevent: 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 15  Compaction of Subgrade: If the existing subgrade under the stone bed is to be used for infiltration, then the subgrade shall not be compacted or subject to excessive construction equipment traffic prior to stone bed placement.  Contamination of Stone Bed and Pervious Pavement with Sediment and Fines: Control of sediment is critical and rigorous installation and maintenance of erosion and sediment control measures is required to prevent sediment deposition on the pavement surface or within the stone bed. Staging, construction practices, and erosion and sediment control must all be taken into consideration when using pervious pavements. Due to the nature of construction sites, pervious pavement and other infiltration measures should be installed at the end of the construction period. All pervious pavement installations must have a backup method for water to enter the stone storage bed in the event that the pavement fails or is altered. In uncurbed lots, this backup drainage may consist of an unpaved 2-foot-wide stone edge drain connected directly to the bed between the wheel stop. In curbed lots, inlets with 12-inch sediment traps may be required at low spots. Backup drainage elements will ensure the functionality of the infiltration system if the pervious pavement is compromised. These systems should be designed by the project civil engineer. 8.4 Temporary and Permanent Excavation Slopes Safe temporary excavations are the responsibility of the Contractor and depend on the actual site conditions at the time of construction. Temporary cuts are the responsibility of the Contractor and should comply with applicable Occupational Safety and Health Administration (OSHA) and Washington Industrial Safety and Health Administration Standards. For trench safety purposes, the fill material at the site should be considered as OSHA “Class C” material, which requires side slopes no steeper than 1.5 Horizontal to 1 Vertical (1.5H:1V). Cut slopes during construction, particularly during wet weather, should be compacted to achieve a dense surface and covered with plastic sheeting to reduce erosion. All traffic and/or construction equipment loads should be set back from the edge of the cut slopes a minimum of 5 feet. Excavated material, stockpiles of construction materials, and equipment should not be placed closer to the edge of any excavation than the depth of the excavation, unless the excavation is shored and such materials are accounted for as a surcharge load on the shoring system. Permanent slopes excavated in dense native soils should be no steeper than 1.5H:1V. We recommend that permanent slopes in on-site fill materials be no steeper than 2H:1V. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 16 8.5 Erosion Control Erosion control for the site will include the Best Management Practices incorporated in the civil design drawings and may incorporate the following recommendations:  Limit exposed cut slopes.  Route surface water through temporary drainage channels around and away from exposed slopes.  Use silt fences, straw, and temporary sedimentation ponds to collect and hold eroded material on the site.  Seed or plant vegetation on exposed areas where work is completed and no buildings are proposed.  Retain existing vegetation to the greatest possible extent. 8.6 Construction Drainage Even during dry weather, we recommend that site drainage measures be incorporated into the project construction. Perched water in the excavations (if present) and surface runoff can be controlled during construction by careful grading practices. Typically, these include the construction of shallow perimeter ditches or low earthen berms, and the use of temporary sumps to collect runoff and prevent water from damaging slopes and exposed subgrades. All collected water should be directed, under control, to a positive and permanent discharge system. The site will need to be graded at all times to facilitate drainage and minimize the ponding of water. 8.7 Subsurface Drainage We recommend installing a subdrain system along the outside of the perimeter footings to prevent pooling of stormwater against the building foundations. The subdrain system should consist of a perforated or slotted, 4-inch (minimum)-diameter plastic pipe bedded in ⅜-inch to No. 8 size washed pea gravel. Where a perforated or slotted drain pipe from a subdrain system connects into a tightline, we recommend that a low permeability concrete collar or dam be placed along the first 2 feet of the tightline to force all water into the tightline. Cleanouts should be provided at convenient locations along all drain lines, such as at the building corners. 8.8 Utilities In general, utilities at the site can be installed within the existing site soils, provided they are not underlain by extremely loose, soft, or organic materials. Maintaining safe utility excavations is 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 17 the responsibility of the Contractor. Conventional excavation equipment can be used to excavate the soils. The utility trenches should be backfilled as noted in Section 8.1. We recommend utilities placed under the roadway have a minimum cover of 2 feet from the crown of the pipes or conduits to the top of the pavement subgrade. Catch basins, utility vaults, and other structures installed flush with the pavement should be designed and constructed to transfer wheel loads to the base of the structure. 8.9 Wet Weather Earthwork In the project area, wet weather generally begins about mid-October and continues through about May, although rainy periods may occur at any time of the year. Therefore, it would be advisable to schedule earthwork during the dry weather months of June through mid-October. Most of the soils at the site contain sufficient fines to produce an unstable mixture when wet. Such soils are highly susceptible to changes in water content, and may become muddy, unstable, and difficult to compact if their moisture content significantly exceeds the optimum. Performing earthwork during dry weather would reduce these problems and costs associated with rainwater, trafficability, and handling of wet soil. However, should wet weather/wet condition earthwork be unavoidable, the following recommendations are provided:  Earthwork should be accomplished in small sections to minimize exposure to wet conditions. That is, each section should be small enough such that the removal of unsuitable soils and the placement and compaction of clean structural fill can be accomplished on the same day. If there is to be traffic over the exposed subgrade, the subgrade should be protected with a compacted layer (generally 8 inches or more) of clean crushed rock.  Fill material should consist of clean, well-graded granular soil, of which not more than 5 percent by dry weight passes the No. 200 mesh sieve, based on wet sieving the fraction passing the ¾-inch mesh sieve. The fines should be non-plastic.  The ground surface in the construction area should be sloped and sealed with a smooth-drum roller to promote the rapid runoff of precipitation, to prevent surface water from flowing into excavations, and to prevent ponding of water.  No soil should be left uncompacted and exposed to moisture. A smooth-drum vibratory roller, or equivalent, should be used to seal the ground surface. Soils which become too wet for compaction should be removed and replaced with clean granular soil.  Excavation and placement of structural fill material should be observed on a full-time basis by a geotechnical engineer or his/her representative, experienced in wet-weather earthwork, to determine that all work is being accomplished in accordance with the project plans and specifications, and our recommendations. 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 18  Covering of work areas, soil stockpiles, or slopes with plastic; sloping, ditching, and installing sumps; dewatering; and other measures should be employed, as necessary, to permit proper completion of the work. Bales of straw and/or geotextile silt fences should be aptly located to control soil movement and erosion.  Grading and earthwork should not be accomplished during periods of heavy, continuous rainfall. 8.10 Plans Review and Construction Observation We recommend that Shannon & Wilson be retained to review those portions of the plans and specifications that pertain to the geotechnical aspects of the project to determine if they are consistent with our recommendations. We also recommend that we be retained to observe the geotechnical aspects of construction, particularly the pavement and shallow footing subgrade preparation, drainage installation, and earthwork (structural fill placement and compaction). This observation would allow us to witness the subsurface conditions as they are exposed during construction and to determine that the work is accomplished in accordance with our recommendations. 9.0 LIMITATIONS This report was prepared for the exclusive use of the Edmonds School District No. 15 for specific application to the design of the Madrona K-8 School project at this site as it relates to the geotechnical aspects discussed in this report. The data and report should be provided to prospective contractors and/or the Contractor for factual information only. Our judgments, conclusions, and interpretations presented in the report should not be construed as a warranty of subsurface conditions and should not be relied upon by prospective contractors. Construction period observation by our firm is necessary to confirm recommendations and interpretations made in this report. The analyses, conclusions, and recommendations presented in this report were prepared in accordance with generally accepted professional geotechnical engineering principles and practice in this area at this time. No other warranty, either express or implied, is made. The analyses, conclusions, and recommendations contained in this report are based on site conditions as they existed during our site visits and explorations, and further assume that the explorations are representative of the subsurface conditions throughout the site; i.e., the subsurface conditions everywhere are not significantly different from those disclosed by the explorations. If subsurface conditions different from those described in this report are observed 21-1-22082-004-R1f.docx/wp/lkn 21-1-22082-004 20 10.0 REFERENCES American Association of State Highway and Transportation Officials (AASHTO), 1993, AASHTO guide for design of pavement structures, Washington, D.C., AASHTO, 2 v. American Concrete Institute (ACI), 2013, Specification for pervious concrete pavement (ACI 522.1): Farmington Hills, Mich., American Concrete Institute, ACI 522.1-13, 7 p. ASTM International (ASTM), 2012, Standard test methods for laboratory compaction characteristics of soil using modified effort (56,000 ft-lbf/ft3 (2,700 kN-m/m3)), D1557- 12e1: West Conshohocken, Pa., ASTM International, Annual book of standards, v. 04.08, soil and rock (I): D420 - D5876, 14 p., available: www.astm.org. Edmonds, Wash., 2016, Natural resources: Edmonds, Wash., Edmonds City Code and Development Code Title 23, available: http://www.codepublishing.com/WA/Edmonds/. International Code Council, Inc., 2014, International building code 2015: Country Club Hills, Ill., International Code Council, Inc., 700 p. Kramer, S.L., 1996, Geotechnical earthquake engineering: Upper Saddle River, N.J., Prentice Hall, 653 p. Shannon & Wilson, Inc. (Shannon & Wilson), 2016, Hydrogeologic report, new Madrona K-8 project, Edmonds, Washington: Report prepared by Shannon & Wilson, Inc., Seattle, Wash., 21-1-22082-003, for Edmonds School District No. 15, Edmonds, Wash., November. Troost, K.G., and Booth, D.B., 2008, Geology of Seattle and the Seattle area, Washington, in Baum, R.L., Godt, J.W. and Highland, L.M., eds., Landslides and Engineering Geology of the Seattle, Washington, Area: Geologic Society of America Reviews in Engineering Geology XX, p. 1-35. Washington State Department of Transportation (WSDOT), 2015, WSDOT Pavement Policy: Olympia, Washington, WSDOT, 131 p., available: http://www.wsdot.wa.gov/NR/rdonlyres/EF9AAC9E-6323-4B09-A3D1- DD2E2C905D02/0/WSDOTPavementPolicyJune2015.pdf Washington Department of Transportation (WSDOT), 2016, Standard specifications for road, bridge, and municipal construction: Olympia, Wash., WSDOT, Manual M 41-10, 1 v., January, available: http://www.wsdot.wa.gov/Publications/Manuals/M41-10.htm. 99 104 PROJECT LOCATION VICINITY MAP FIG. 1 Geotechnical Report New Madrona K-8 Project Edmonds, Washington Map adapted from aerial imagery provided by Google Earth Pro, reproduced by permission JUDQWHGE\*RRJOH(DUWK0DSSLQJ6HUYLFH NOTE October 2016 21-1-22082-004 Fi l e n a m e : J : \ 2 1 1 \ 2 2 0 8 2 - 0 0 4 \ 2 - 1 - 2 2 0 8 4 - 0 0 4 F i g 1 - V i c M a p . d w g D a t e : 1 0 - 0 4 - 2 0 1 6 L o g i n : S A C Edmonds Washington Project Location 90 5 97 MT 0 800 1600 Approximate Scale in Feet B-12 B-11 TP-3F PIT-3 TP-2F EXISTING BUILDING 23704 TP-9 TP-5 TP-1 TP-13TP-2 TP-4 TP-6 TP-14 TP-3 TP-7 TP-8 TP-10 TP-16 TP-11 TP-15 TP-12 TP-3F TP-2F TP-1F B-2 B-3 B-4 B-5 PIT-1 B-8 B-9 B-6 B-10 PIT-2 PROPOSED BUILDING B-7 FIG. 2 FI G . 2 SITE AND EXPLORATION PLAN Filename: J:\211\22082-004\2-1-22084-004 Fig 2 - Site Plan.dwg Layout: Layout Date: 10-04-2016 Login: SAC Geotechnical Report New Madrona K-8 Project Edmonds, Washington October 2016 21-1-22082-004 B-1 Boring Designation and Approximate Location Test Pit Designation and Approximate Location (2016) Infiltration Test Pit Designation and Approximate Location Previous Test Pit Designation and Approximate Location (2015) LEGEND NOTE Figure adapted from client file, Topo and Survey.dwg, received 10-3-16. 0 100 200 Scale in FeetTP-1F PIT-3 TP-1 Fi l e : J : \ 2 1 1 \ 2 2 0 8 2 - 0 0 4 \ 2 - 1 - 2 2 0 8 4 - 0 0 4 F i g 3 - R o c k e r y D e t a i l . d w g D a t e : 1 0 - 0 4 - 2 0 1 6 A u t h o r : S A C Not to Scale 4 12" Min. 6" Min. 1 Clean, well-graded sand and gravel or crushed rock, 2-inch maximum size, 40 to 60% gravel, less than 5% fines (passing #200 sieve). Fines shall be non-plastic. Compact in 4" lifts with minimum of 4 coverages by hand-operated tamper. Compact to at least 92% of Modified Proctor maximum dry density (ASTM D-1557). Backfill and rock placement should be built up together. Opening Chinked with 2 to 4-inch Quarry Spalls Stable Excavation Slope in Very Dense Native Soil (Contractor's Responsibility) Backfill H/3 Min. Width for Base Rock All loose soil at rockery foundation subgrade should be overexcavated down to medium dense to very dense soil and replaced with compacted backfill as described above. The excavation shall be kept free of water. The prepared foundation subgrade shall be evaluated by a soils engineer prior to placement of rock. 8" Compacted Native or Imported Soil (Impervious Surface Layer) 16" Min. Width for Top Rock H = 6 Ft. Max. Medium dense to Very Dense Native Soil 6" Diameter Slotted Pipe Bedded in washed 3/8" to No.8 sieve size pea gravel (6" cover around pipe), sloped to drain and connected by tightline to storm drain outfall or other appropriate outlets. No fabric around pipe. Maximum slot width is 1/8". Very Dense Undisturbed Native Soil Rock shall be sound and have a minimum density of 160 pounds per cubic foot. MINIMUM WEIGHT OF ROCK TYPICAL ROCKERY DETAIL FIG. 3 Ditch Drain to Appropriate Outlets Geotechnical Report New Madrona K-8 Project Edmonds, Washington October 2016 21-1-22082-004 PIT Results-Figure 4 PIT-1 Plot-9/28/2016-pvh 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 200 400 600 800 1000 1200 1400 Me a s u r e d I n f l o w R a t e ( G P M ) W a t e r H e i g h t A b o v e B o t t o m o f T e s t P i t F l o o r ( F e e t ) Time Since Start of Saturation (Minutes) Transducer Reading (Feet) Manual Reading (Feet) Inflow Rate (GPM) FI G . 4 Geotechnical Report New Madrona K-8 Project Edmonds,Washington MEASURED WATER LEVEL PILOT INFILTRATION TEST PIT-1 September 2016 21-1-22082-004 FIG. 4SHANNON& WILSON, INC. Geotechnical and Environmental Consultants NOTE 1. This small-scale pilot infiltration test (PIT) was performed on 7/28/16. Water was added from 10:31 to 19:28. Approximate grade elevation 444.5 feet (NAVD88). Test pit floor depth 3.8 feet deep. A flow rate of 0.75 to 0.12 gallons per minute (gpm) was maintained for the initial saturation period. During the last hour of saturation, the flow rate was 0.11 gpm, with a water level of 14.25 inches above the test pit bottom. Test test pit drained from 19:28 on 7/28/16 to about 6:00 on 7/29/16. Test pit dimensions during the PIT were approximately 2.4 feet (north-south) by 5.5 feet (east- west), or 13.2 square feet. The test pit was over-excavated on 7/29/16 (starting at 8:30) to 10 feet deep. No sign of water was observed during over-excavation. Transducer was inside a stilling tube. Approx. 5" mud accumulated around the tube bottom by end of test. Water level in tube fell below surrounding mud level. Residual water perched on silt muck at test pit bottom. Soils immediately below were moist. PIT Results-Figure 5 PIT-2 Plot-9/28/2016-pvh 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 200 400 600 800 1000 1200 1400 1600 Me a s u r e d I n f l o w R a t e ( G P M ) W a t e r H e i g h t A b o v e B o t t o m o f T e s t P i t F l o o r ( F e e t ) Time Since Start of Saturation (Minutes) Transducer Reading (Feet) Manual Reading (Feet) Inflow Rate (GPM) FI G . 5 Geotechnical Report New Madrona K-8 Project Edmonds,Washington MEASURED WATER LEVEL PILOT INFILTRATION TEST PIT-2 September 2016 21-1-22082-004 FIG. 5SHANNON& WILSON, INC. Geotechnical and Environmental Consultants NOTE 1. This small-scale pilot infiltration test (PIT) was performed on 7/28/16. Water was added from 11:28 to 18:53. Approximate grade elevation 456 feet (NAVD88). Test pit floor depth 3.3 feet deep. A flow rate of 3.75 to 0.04 gallons per minute (gpm) was maintained for the initial saturation period. During the last hour of saturation, the flow rate was 0.04 gpm, with a water level of 15.75 inches above the test pit bottom. Test test pit drained from 18:53 on 7/28/16 to about 11:50 on 7/29/16. Test pit dimensions during the PIT were approximately 2.1 feet (north-south) by 6.3 feet (east- west), or 13.2 square feet. The test pit was over-excavated on 7/29/16 to 4.5 feet deep. The back hoe scooped out the residual PIT water and found that it had been perched on moist till. Residual water remaining in test pit over 16 hours after ceasing inflow. PIT Results-Figure 6 PIT-3 Plot-9/28/2016-pvh 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 200 400 600 800 1000 1200 1400 Me a s u r e d I n f l o w R a t e ( G P M ) W a t e r H e i g h t A b o v e B o t t o m o f T e s t P i t F l o o r ( F e e t ) Time Since Start of Saturation (Minutes) Transducer Reading (Feet) Manual Reading (Feet) Inflow Rate (GPM) FI G . 6 Geotechnical Report New Madrona K-8 Project Edmonds,Washington MEASURED WATER LEVEL PILOT INFILTRATION TEST PIT-3 September 2016 21-1-22082-004 FIG. 6SHANNON& WILSON, INC. Geotechnical and Environmental Consultants NOTE 1. This small-scale pilot infiltration test (PIT) was performed on 7/28/16. Water was added from 13:07 to 20:38. Approximate grade elevation 450 feet (NAVD88). Test pit floor depth 2.9 feet deep. A flow rate of 3.33 to 0.06 gallons per minute (gpm) was maintained for the initial saturation period. During the last hour of saturation, the flow rate was 0.06 gpm, with a water level of 16.2 inches above the test pit bottom. Test test pit drained from 20:38 on 7/28/16 to about 12:36 on 7/29/16 when we removed the transducer. Inital ponded area dimensions during the PIT were approximately 2.2 feet (east-west) by 8 feet (north-south), or 17.6 square feet. Due to sidewall slumping during the falling head test period, the final ponded dimensions were approximate 2.5 feet by 8.2 feet (20.5 square feet). The test pit was over-excavated on 7/29/16 to 3.4 feet deep. The back hoe scooped out the residual PIT water and found that it had been perched on moist till. Residual water remaining in test pit over 16 hours after ceasing inflow. 21-1-22082-004 APPENDIX A SUBSURFACE EXPLORATIONS October 2016 21-1-22082-004 Geotechnical Report New Madrona K-8 Project Edmonds, Washington 1Gravel, sand, and fines estimated by mass. Other constituents, such as organics, cobbles, and boulders, estimated by volume. 2Reprinted, with permission, from ASTM D2488 - 09a Standard Practice for Description and Identification of Soils (Visual-Manual Procedure), copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be obtained from ASTM International, www.astm.org. 140 pounds with a 30-inch free fall. Rope on 6- to 10-inch-diam. cathead 2-1/4 rope turns, > 100 rpm NOTE: If automatic hammers are used, blow counts shown on boring logs should be adjusted to account for efficiency of hammer. 10 to 30 inches long Shoe I.D. = 1.375 inches Barrel I.D. = 1.5 inches Barrel O.D. = 2 inches Sum blow counts for second and third 6-inch increments. Refusal: 50 blows for 6 inches or less; 10 blows for 0 inches. RELATIVE CONSISTENCY N, SPT, BLOWS/FT.5% to 12% fine-grained: with Silt or with Clay 3 15% or more of a second coarse- grained constituent: with Sand or with Gravel 5 < 5% 5 to 10% 15 to 25% 30 to 45% 50 to 100% Surface Cement Seal Asphalt or Cap Slough Inclinometer or Non-perforated Casing Vibrating Wire Piezometer N, SPT, BLOWS/FT. < 4 4 - 10 10 - 30 30 - 50 > 50 DESCRIPTION < #200 (0.075 mm = 0.003 in.) #200 to #40 (0.075 to 0.4 mm; 0.003 to 0.02 in.) #40 to #10 (0.4 to 2 mm; 0.02 to 0.08 in.) #10 to #4 (2 to 4.75 mm; 0.08 to 0.187 in.) SIEVE NUMBER AND/OR APPROXIMATE SIZE #4 to 3/4 in. (4.75 to 19 mm; 0.187 to 0.75 in.) 3/4 to 3 in. (19 to 76 mm) 3 to 12 in. (76 to 305 mm) > 12 in. (305 mm) Fine Coarse Fine Medium Coarse BOULDERS COBBLES GRAVEL FINES SAND Sheet 1 of 3 CONSTITUENT2 SOIL DESCRIPTION AND LOG KEY SHANNON & WILSON, INC.Geotechnical and Environmental Consultants Absence of moisture, dusty, dry to the touch Damp but no visible water Visible free water, from below water table FIG. A-1 Shannon & Wilson, Inc. (S&W), uses a soil identification system modified from the Unified Soil Classification System (USCS). Elements of the USCS and other definitions are provided on this and the following pages. Soil descriptions are based on visual-manual procedures (ASTM D2488) and laboratory testing procedures (ASTM D2487), if performed. STANDARD PENETRATION TEST (SPT) SPECIFICATIONS Hammer: Sampler: N-Value: Dry Moist Wet MOISTURE CONTENT TERMS Modifying (Secondary) Precedes major constituent Major Minor Follows major constituent 1All percentages are by weight of total specimen passing a 3-inch sieve.2The order of terms is: Modifying Major with Minor.3Determined based on behavior.4Determined based on which constituent comprises a larger percentage.5Whichever is the lesser constituent. COARSE-GRAINED SOILS (less than 50% fines)1 NOTE: Penetration resistances (N-values) shown on boring logs are as recorded in the field and have not been corrected for hammer efficiency, overburden, or other factors. PARTICLE SIZE DEFINITIONS RELATIVE DENSITY / CONSISTENCYSand or Gravel 4 30% or more coarse-grained: Sandy or Gravelly 4 More than 12% fine-grained: Silty or Clayey 3 15% to 30% coarse-grained: with Sand or with Gravel 4 30% or more total coarse-grained and lesser coarse- grained constituent is 15% or more: with Sand or with Gravel 5 Very soft Soft Medium stiff Stiff Very stiff Hard Very loose Loose Medium dense Dense Very dense RELATIVE DENSITY FINE-GRAINED SOILS (50% or more fines)1 COHESIVE SOILS < 2 2 - 4 4 - 8 8 - 15 15 - 30 > 30 COHESIONLESS SOILS Silt, Lean Clay, Elastic Silt, or Fat Clay 3 PERCENTAGES TERMS 1, 2 Trace Few Little Some Mostly WELL AND BACKFILL SYMBOLS Bentonite Cement Grout Bentonite Grout Bentonite Chips Silica Sand Perforated or Screened Casing S&W INORGANIC SOIL CONSTITUENT DEFINITIONS 20 1 3 _ B O R I N G _ C L A S S 1 2 1 - 22 0 8 2 .G P J S H A N _ W I L . G D T 5 / 1 5 / 1 4 October 2016 21-1-22082-004 Geotechnical Report New Madrona K-8 Project Edmonds, Washington GC SC Inorganic Organic (more than 50%of coarsefraction retainedon No. 4 sieve) MAJOR DIVISIONS GROUP/GRAPHICSYMBOL CH OH ML CL TYPICAL IDENTIFICATIONS Gravel Sand Silty Sand; Silty Sand with Gravel Clayey Sand; Clayey Sand with Gravel Clayey Gravel; Clayey Gravel withSand Sheet 2 of 3 Gravels Primarily organic matter, dark incolor, and organic odor SW (more than 12%fines) Silts and Clays Silts and Clays (more than 50%retained on No.200 sieve) (50% or more of coarse fraction passes the No. 4 sieve) (liquid limit less than 50) (liquid limit 50 ormore) Organic Inorganic FINE-GRAINEDSOILS SM Sands Silty or ClayeyGravel Silt; Silt with Sand or Gravel; Sandy orGravelly Silt Organic Silt or Clay; Organic Silt orClay with Sand or Gravel; Sandy orGravelly Organic Silt or Clay HIGHLY-ORGANIC SOILS COARSE-GRAINEDSOILS OL (less than 5% fines) GW Geotechnical and Environmental Consultants SHANNON & WILSON, INC. (less than 5%fines) PT FIG. A-1 (more than 12% fines) MH SP GP GM Silty orClayey Sand Silty Gravel; Silty Gravel with Sand (50% or more passes the No. 200 sieve) SOIL DESCRIPTION AND LOG KEY Elastic Silt; Elastic Silt with Sand or Gravel; Sandy or Gravelly Elastic Silt Fat Clay; Fat Clay with Sand or Gravel; Sandy or Gravelly Fat Clay Organic Silt or Clay; Organic Silt or Clay with Sand or Gravel; Sandy or Gravelly Organic Silt or Clay Poorly Graded Sand; Poorly Graded Sand with Gravel Well-Graded Sand; Well-Graded Sand with Gravel Well-Graded Gravel; Well-GradedGravel with Sand Poorly Graded Gravel; Poorly GradedGravel with Sand Lean Clay; Lean Clay with Sand or Gravel; Sandy or Gravelly Lean Clay NOTES 1. Dual symbols (symbols separated by a hyphen, i.e., SP-SM, Sand with Silt) are used for soils with between 5% and 12% fines or when the liquid limit and plasticity index values plot in the CL-ML area of the plasticity chart. Graphics shown on the logs for these soil types are a combination of the two graphic symbols (e.g., SP and SM). 2. Borderline symbols (symbols separated by a slash, i.e., CL/ML, Lean Clay to Silt; SP-SM/SM, Sand with Silt to Silty Sand) indicate that the soil properties are close to the defining boundary between two groups. Peat or other highly organic soils (see ASTM D4427) 20 1 3 _ B O R I N G _ C L A S S 2 2 1 -2 2 0 8 2 .G P J S H A N _ W I L . G D T 5 / 1 5 / 1 4 NOTE: No. 4 size = 4.75 mm = 0.187 in.; No. 200 size = 0.075 mm = 0.003 in. UNIFIED SOIL CLASSIFICATION SYSTEM (USCS) (Modified From USACE Tech Memo 3-357, ASTM D2487, and ASTM D2488) October 2016 21-1-22082-004 Geotechnical Report New Madrona K-8 Project Edmonds, Washington SHANNON & WILSON, INC.Geotechnical and Environmental Consultants FIG. A-1 Sheet 3 of 3 SOIL DESCRIPTION AND LOG KEY 1Reprinted, with permission, from ASTM D2488 - 09a Standard Practice for Description and Identification of Soils (Visual-Manual Procedure), copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be obtained from ASTM International, www.astm.org. 2Adapted, with permission, from ASTM D2488 - 09a Standard Practice for Description and Identification of Soils (Visual-Manual Procedure), copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard may be obtained from ASTM International, www.astm.org. Interbedded Laminated Fissured Slickensided Blocky Lensed Homogeneous ATD Diam. Elev. ft. FeO gal. Horiz. HSA I.D. in. lbs. MgO mm MnO NA NP O.D. OW pcf PID PMT ppm psi PVC rpm SPT USCS qu VWP Vert. WOH WOR Wt. Crumbles or breaks with handling or slight finger pressure. Crumbles or breaks with considerable finger pressure. Will not crumble or break with finger pressure. PLASTICITY2 CEMENTATION TERMS1 GRADATION TERMS STRUCTURE TERMS1 ACRONYMS AND ABBREVIATIONS Alternating layers of varying material or color with layers at least 1/4-inch thick; singular: bed. Alternating layers of varying material or color with layers less than 1/4-inch thick; singular: lamination. Breaks along definite planes or fractures with little resistance. Fracture planes appear polished or glossy; sometimes striated. Cohesive soil that can be broken down into small angular lumps that resist further breakdown. Inclusion of small pockets of different soils, such as small lenses of sand scattered through a mass of clay. Same color and appearance throughout. Narrow range of grain sizes present or, within the range of grain sizes present, one or more sizes are missing (Gap Graded). Meets criteria in ASTM D2487, if tested. Full range and even distribution of grain sizes present. Meets criteria in ASTM D2487, if tested. Poorly Graded Well-Graded Weak Moderate Strong Irregular patches of different colors. Soil disturbance or mixing by plants or animals. Nonsorted sediment; sand and gravel in silt and/or clay matrix. Material brought to surface by drilling. Material that caved from sides of borehole. Disturbed texture, mix of strengths. VISUAL-MANUAL CRITERIA A 1/8-in. thread cannot be rolled at any water content. A thread can barely be rolled and a lump cannot be formed when drier than the plastic limit. A thread is easy to roll and not much time is required to reach the plastic limit. The thread cannot be rerolled after reaching the plastic limit. A lump crumbles when drier than the plastic limit. It takes considerable time rolling and kneading to reach the plastic limit. A thread can be rerolled several times after reaching the plastic limit. A lump can be formed without crumbling when drier than the plastic limit. Sharp edges and unpolished planar surfaces. Similar to angular, but with rounded edges. Nearly planar sides with well-rounded edges. Smoothly curved sides with no edges. Width/thickness ratio > 3. Length/width ratio > 3. PARTICLE ANGULARITY AND SHAPE TERMS1 ADDITIONAL TERMS Angular Subangular Subrounded Rounded Flat Elongated DESCRIPTION Nonplastic Low Medium High At Time of Drilling Diameter Elevation Feet Iron Oxide Gallons Horizontal Hollow Stem Auger Inside Diameter Inches Pounds Magnesium Oxide Millimeter Manganese Oxide Not Applicable or Not Available Nonplastic Outside Diameter Observation Well Pounds per Cubic Foot Photo-Ionization Detector Pressuremeter Test Parts per Million Pounds per Square Inch Polyvinyl Chloride Rotations per Minute Standard Penetration Test Unified Soil Classification System Unconfined Compressive Strength Vibrating Wire Piezometer Vertical Weight of Hammer Weight of Rods Weight Mottled Bioturbated Diamict Cuttings Slough Sheared APPROX. PLASITICITY INDEX RANGE < 4 4 to 10 10 to 20 > 20 20 1 3 _ B O R I N G _ C L A S S 3 2 1 - 22 0 8 2 .G P J S H A N _ W I L . G D T 5 / 1 5 / 1 4 0.4 4.5 16.5 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Asphalt. Dense, red-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; few organics. Topsoil/Weathered Glacial Till Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to angular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Moist to wet below about 15 feet. BOTTOM OF BORING COMPLETED 7/26/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-2 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-2SHANNON & WILSON, INC. 16.5 ft. ~ 449 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 94/9" 90/10" 88/10" 50/4" 0.4 4.5 15.9 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Asphalt. Dense, gray-brown, Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Weathered Glacial Till Very dense, gray-brown, Silty Sand (SM) to Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Diamict pockets from 7.5 to 9 feet. - Moist to wet below about 15 feet. BOTTOM OF BORING COMPLETED 7/26/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-3 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-3SHANNON & WILSON, INC. 15.9 ft. ~ 447.5 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 50/6" 50/6" 50/5" 50/5" 0.4 9.5 15.8 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Asphalt. Medium dense, brown, Silty Sand (SM) to Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to angular gravel; fine to coarse sand; nonplastic fines; trace to few organics; trace diamict pockets below about 7 feet. Fill Very dense, gray-brown, Silty Sand (SM) to Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till BOTTOM OF BORING COMPLETED 7/26/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-4 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-4SHANNON & WILSON, INC. 15.8 ft. ~ 445 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 90 78 50/3" 0.5 4.5 7.0 16.0 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Topsoil. Medium dense, gray-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to angular gravel; fine to coarse sand; nonplastic fines; trace organics. Fill Loose, red-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; trace organics. Topsoil/Weathered Glacial Till Dense to very dense, gray-brown, Silty Sand (SM) to Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Slight iron oxide staining from 7 to 9 feet. - Moist to wet below about 15 feet. BOTTOM OF BORING COMPLETED 7/26/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-5 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-5SHANNON & WILSON, INC. 16 ft. ~ 447 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 50/5" 83/9" 50/6" 9.0 15.9 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Medium dense to very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Weathered Glacial Till Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to angular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till BOTTOM OF BORING COMPLETED 7/25/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-6 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-6SHANNON & WILSON, INC. 15.9 ft. ~ 455 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 68/11" 84/10" 50/5" 0.2 4.5 15.9 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Asphalt. Medium dense, brown, Silty Sand (SM); moist; few fine, subrounded to subangular gravel; fine to coarse sand; nonplastic to low plasticity fines; diamict; trace organics. Topsoil/Weathered Glacial Till Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to subangular gravel; fine to coarse sand; nonplastic fines. Glacial Till - Trace pockets of poorly graded sand with silt below about 15 feet. BOTTOM OF BORING COMPLETED 7/26/2016 * * De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-7 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-7SHANNON & WILSON, INC. 15.9 ft. ~ 454 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 50/3" 50/5" 50/4" 50/5" 50/5" 0.2 15.8 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Asphalt. Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to angular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Gray below about 12 feet. BOTTOM OF BORING COMPLETED 7/25/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-8 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-8SHANNON & WILSON, INC. 15.8 ft. ~ 456 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 50/3" 50/5" 50/4" 50/3" 50/2" 50/4" 0.5 7.0 15.5 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Topsoil. Dense to very dense, brown and gray, Silty Sand with Gravel (SM); dry to moist; fine to coarse, subrounded to angular gravel; fine to coarse sand; nonplastic fines; trace organics; diamict pockets. Fill/Weathered Glacial Till Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Few pockets of poorly graded, fine to medium sand with silt pockets below about 12 feet; moist to wet from about 12 to 14 feet. BOTTOM OF BORING COMPLETED 7/25/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-9 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-9SHANNON & WILSON, INC. 15.5 ft. ~ 456 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 78 91/11" 62 50/4" 50/6" 0.5 7.0 15.8 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Topsoil. Medium dense, brown, Silty Sand (SM); dry to moist; few fine, subrounded to subangular gravel; fine to medium sand; nonplastic fines; diamict pockets; trace organics. Fill - Roots at about 5 feet. Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to angular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Mottled orange and gray-brown with pockets of iron oxide staining from 7 to 9 feet. BOTTOM OF BORING COMPLETED 7/25/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-10 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-10SHANNON & WILSON, INC. 15.8 ft. ~ 454.5 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 71/9" 50/5" 50/3" 50/4" 0.5 4.5 16.4 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Topsoil. Dense, gray-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Weathered Glacial Till Very dense, gray-brown, Silty Sand (SM) to Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till BOTTOM OF BORING COMPLETED 7/25/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-11 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-11SHANNON & WILSON, INC. 16.4 ft. ~ 456 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 84/11" 62 50/6" 50/5" 85/5" 0.5 4.5 16.3 No n e O b s e r v e d D u r i n g D r i l l i n g 1 2 3 4 5 6 Topsoil. Medium dense, brown, Silty Sand with Gravel (SM); dry to moist; fine, subrounded to subangular gravel; fine to medium sand; nonplastic fines; trace organics. Fill Very dense, gray-brown, Silty Sand with Gravel (SM); moist; fine, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Glacial Till - Trace organics from about 4.5 to 8.5 feet. BOTTOM OF BORING COMPLETED 7/25/2016 De p t h , f t . Geotechnical Report New Madrona K-8 Project Edmonds, Washington De p t h , f t . 2 4 6 8 10 12 14 16 18 Drilling Method: Drilling Company: Drill Rig Equipment: Other Comments: Lo g : K J W Northing: Easting: Station: Offset: SOIL DESCRIPTION 20 40 60 Sa m p l e s 6 in. 2-inch Refer to the report text for a proper understanding of the subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual. * LOG OF BORING B-12 0 60 0 Total Depth: Top Elevation: Vert. Datum: Horiz. Datum: Gr o u n d Wa t e r NOTES 20 40 2.0" O.D. Split Spoon Sample Hole Diam.: Rod Diam.: Hammer Type: LEGEND Sy m b o l 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. Groundwater level, if indicated above, is for the date specified and may vary. 3. USCS designation is based on visual-manual classification and selected lab testing. Hollow Stem Auger Holocene Drilling Diedrich D-50 FIG. A-12SHANNON & WILSON, INC. 16.3 ft. ~ 456 ft. NAVD 88 Re v : E A S September 2016 21-1-22082-004 Ty p : L K N Geotechnical and Environmental Consultants Sample Not Recovered REV 3 - Approved for Submittal MA S T E R _ L O G _ E 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 1 0 / 3 / 1 6 PENETRATION RESISTANCE Hammer Wt. & Drop: (blows/foot) 140 lbs / 30 inches % Water Content % Fines (<0.075mm) 50/6" 50/5" 50/2" 90/9" LOG OF TEST PIT PIT-1 SOIL DESCRIPTION Sketch of ________ Pit Side 0 2 4 6 8 10 12 Horizontal Distance in Feet Gr o u n d Wa t e r % W a t e r Co n t e n t Sa m p l e s De p t h , F t . 0 2 4 6 8 10 12 Topsoil and grass. Dense, brown, Silty Sand with Gravel (SM); moist. Fill (Reworked Till) Very loose to dense, brown-gray, Silty Sand with Gravel and Cobbles (SM); moist; few cobbles, fine to coarse subrounded to subangular gravel; fine to coarse sand; non-plastic fines; minor iron-oxide staining at 3.8 feet; diamict pockets. Fill Medium dense to dense, brown to red-brown, Silty Sand with Gravel (SM); moist; fine to coarse subrounded to angular gravel; fine to coarse sand; non-plastic fines. Fill Medium dense to dense, red-brown to brown, Silty Sand with Gravel and Cobbles (SM); moist; few rounded cobbles; fine to coarse subrounded to subangular gravel; fine to coarse sand; non-plastic fines; roots and conifer duff at top. Weathered Till 2 3 S-1 North No n e O b s e r v e d FI G . A - 13 1 File: J:\211\22082-004\2-1-22084-004 TPs.dwg Date: 08-30-2016 Author: SAC 3 4 5 Fine Roots JOB NO:DATE: PROJECT:Madrona K-8 LOCATION:See Site and Exploration Plan Surface Elevation: Approx. 445 Ft. 4 5 1 2 S-2 S-3 S-4 S-5 S-6 S-7 Test Pit Floor During Pilot Infiltration Test (PIT) T-Probe 1" Penetration (before PIT) T-Probe 2.5" Penetration (after PIT) T-Probe 1.5" Penetration (after PIT) T-Probe 0.5" Penetration (after PIT) T-Probe 17" Penetration (after PIT) Roots and Conifer Duff/Needles 1. Small-scale PIT performed at 3.8 feet on 7-28/7-29-16. 2. PIT ponded area 2.4' x 5.5'. NOTES 21-1-22082-004 7-28-16 to 7-29-16 Test Pit Floor After PIT LOG OF TEST PIT PIT-2 SOIL DESCRIPTION Sketch of ________ Pit Side 0 2 4 6 8 10 12 Horizontal Distance in Feet Gr o u n d Wa t e r % W a t e r Co n t e n t Sa m p l e s De p t h , F t . 0 2 4 6 8 10 12 Topsoil. Very dense, brown to gray-brown, Silty Sand with Gravel and Cobbles (SM); dry to moist; few cobbles; fine to coarse subrounded to subangular gravel; fine to medium sand; non-plastic fines; diamict. Till 2 North No n e O b s e r v e d FI G . A - 14 1 File: J:\211\22082-004\2-1-22084-004 TPs.dwg Date: 08-30-2016 Author: SAC JOB NO:DATE:21-1-22082-004 7-28-16 to 7-29-16PROJECT:Madrona K-8 LOCATION:See Site and Exploration Plan Surface Elevation: Approx. 456 Ft. 1 2 Test Pit Floor During Pilot Infiltration Test (PIT) T-Probe 0.5" Penetration (after PIT) T-Probe 0" Penetration (after PIT) Test Pit Floor After PIT 1. Small-scale PIT performed at 3.3 feet on 7-28/7-29-16. 2. PIT ponded area 2.1' x 6.3'. NOTES S-1 S-2 LOG OF TEST PIT PIT-3 SOIL DESCRIPTION Sketch of ________ Pit Side 0 2 4 6 8 10 12 Horizontal Distance in Feet Gr o u n d Wa t e r % W a t e r Co n t e n t Sa m p l e s De p t h , F t . 0 2 4 6 8 10 12 Topsoil. Medium dense to dense, brown, Silty Sand with Gravel (SM); dry to moist; scattered cobbles and boulders. Fill (Reworked Till) Very dense, gray-brown, Silty Sand with Gravel and Cobbles and Boulders (SM); dry to moist; few cobbles and boulders; fine to coarse subrounded to subangular gravel; fine to coarse sand; non-plastic fines; diamict. Weathered Till to Till 2 West No n e O b s e r v e d FI G . A - 15 1 File: J:\211\22082-004\2-1-22084-004 TPs.dwg Date: 08-30-2016 Author: SAC 1. Small-scale PIT performed at 2.9 feet on 7-28/7-29-16. 2. PIT ponded area 2.2' x 8.0' on 7-28-16. PIT ponded area 2.5' x 8.2' on 7-29-16. NOTES JOB NO:DATE: PROJECT:Madrona K-8 LOCATION:See Site and Exploration Plan Surface Elevation: Approx. 450 Ft. 1 2 Test Pit Floor During Pilot Infiltration Test (PIT) T-Probe 0.5" Penetration (after PIT) Test Pit Floor After PIT3 T-Probe 0" Penetration (after PIT) 3 21-1-22082-004 7-28-16 to 7-29-16 S-1 S-2 LOG OF TEST PIT TP-1F SOIL DESCRIPTION Sketch of ________ Pit Side 0 2 4 6 8 10 12 Horizontal Distance in Feet Gr o u n d Wa t e r % W a t e r Co n t e n t Sa m p l e s De p t h , F t . 0 2 4 6 8 10 12 Topsoil Loose to medium dense, brown Silty Sand with Gravel (SM); moist. Fill Very dense, gray to gray-brown, Silty Sand with Gravel, Cobbles, and Boulders (SM); moist; fine to coarse, subrounded to subangular gravel; fine to coarse sand; nonplastic fines; diamict. Till 2 3 East No t E n c o u n t e r e d FI G . A - 1 6 1 File: J:\211\22082-004\PDFs 2016-09-06\2-1-22084-004 TP-XF.dwg Date: 09-06-2016 Author: drtemp JOB NO:DATE: PROJECT:Madrona K-8 LOCATION:Edmonds, WA Surface Elevation: Approx. S-1 1. 9 feet long and 4'-6" wide. 2. 6-inch diameter concrete storm drain encountered 3 feet below ground surface. Repaired with SDR 35 pipe and rubber coupling. NOTES 21-1-22082-004 7-28-16 3 1 Broke/Repaired Storm Drain Pipe 2 LOG OF TEST PIT TP-2F SOIL DESCRIPTION Sketch of ________ Pit Side 0 2 4 6 8 10 12 Horizontal Distance in Feet Gr o u n d Wa t e r % W a t e r Co n t e n t Sa m p l e s De p t h , F t . 0 2 4 6 8 10 12 Topsoil Loose to medium dense, brown, Silty Sand with Gravel (SM); moist; fine to coarse, subrounded to subangular gravel; fine to coarse sand; nonplastic fines. Fill Very dense, gray to gray-brown, Silty Sand with Gravel (SM); moist; diamict. Till Cobbles present. 2 3 East No n e FI G . A - 1 7 1 File: J:\211\22082-004\PDFs 2016-09-06\2-1-22084-004 TP-XF.dwg Date: 09-06-2016 Author: drtemp JOB NO:DATE: PROJECT:Madrona K-8 LOCATION:Edmonds, WA Surface Elevation: Approx. S-1 1. 9 Feet long and 4'-6" wide. NOTES 21-1-22082-004 7-28-16 1 2 3 LOG OF TEST PIT TP-3F SOIL DESCRIPTION Sketch of ________ Pit Side 0 2 4 6 8 10 12 Horizontal Distance in Feet Gr o u n d Wa t e r % W a t e r Co n t e n t Sa m p l e s De p t h , F t . 0 2 4 6 8 10 12 Loose to medium dense, brown, Poorly Graded Sand with Silt and Gravel (SP-SM); dry to moist; few roots. Fill Very dense, gray-brown; Silty Sand with Gravel (SM); moist; diamict. Till 2 S-1 South No t E n c o u n t e r e d FI G . A - 1 8 1 File: J:\211\22082-004\PDFs 2016-09-06\2-1-22084-004 TP-XF.dwg Date: 09-06-2016 Author: drtemp JOB NO:DATE: PROJECT:Madrona K-8 LOCATION:Edmonds, WA Surface Elevation: Approx. S-2 NOTES 21-1-22082-004 8-25-16 1 2 Roots 21-1-22082-004 APPENDIX B LABORATORY TEST RESULTS 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 7.5 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFLAKV8.7345511 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand USCS Group Name C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 BORING B-3 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 B-3, S-31 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 5.0 10.0 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFL JFL AKV AKV 10.2 9.7 41529 40 64 50 8 10 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand Silty Sand USCS Group Name D422 C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 BORING B-4 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 B-4, S-21 B-4, S-41 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 7.5 15.0 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFL JFL AKV AKV 15.0 10.0 82232 33 54 52 14 15 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand Silty Sand with Gravel USCS Group Name D422 C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 BORING B-5 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 B-5, S-31 B-5, S-61 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 5.0 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFLAKV8.1345313 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand USCS Group Name C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 BORING B-11 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 B-11, S-111 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 3.0 7.0 13 1 Test specimen did not meet minimum mass recommendations. 2 Cobble percentages are calculated using the pre-removal, oven-dried mass of the total specimen. USCS Group Symbol, Soil Classification Group Name, Gravel %, Sand %, Fines %, <0.02mm %, <2um%, Cu, and Cc values are calculated from particles smaller than 76.2mm (3 inches) only, per ASTM D2487. Fines % Tested ByllGravel % Sand % JFL JFL AKV AKV 5.7 13.9 29 21 56 51 15 28 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand with Gravel Silty Sand with Gravel and Cobbles Cobbles %2USCS Group Name C136 C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 TEST PIT PIT-1 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 PIT-1, S-11 PIT-1, S-61 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 3.5 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFLAKV8.7335512 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand USCS Group Name C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 TEST PIT PIT-2 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 PIT-2, S-21 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 3.0 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFLAKV5.9274726 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand with Gravel USCS Group Name C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 TEST PIT PIT-3 WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 PIT-3, S-21 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 7.0 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFLAKV7.5315513 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand USCS Group Name C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 TEST PIT TP-1F WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 TP-1F, S-11 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 4.7 5 8 Depth (ft) Sample Identification 6.0 1 Test specimen did not meet minimum mass recommendations. Fines % Tested ByllGravel % Sand % JFLAKV7.3135829 Fine Mesh Opening in Inches Grain Size in Millimeters Preliminary Hydrogeologic Report New Madrona K-8 Project Edmonds, Washington GRAIN SIZE DISTRIBUTION PLOT SiltCoarse Mesh Openings per Inch, U.S. Standard 2 10 0.0 6 0.0 4 0.0 0 3 0.0 0 1 0.0 0 2 0.0 0 3 0.0 0 8 0.0 1 0.0 7 50.10.2136204060 76. 2 Grain Size (mm) Pe r c e n t C o a r s e r b y M a s s 1 1/2 3/8 4 20 USCSGroupSymbol SM 3 100 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0 Silty Sand with Gravel USCS Group Name C136 0.0 0 1 0.0 0 4 0.0 0 6 0.0 4 0.0 60.3 0.0 2 0.0 3 FinesSand 2410 Pe r c e n t F i n e r b y M a s s 200 0.0 2 0.0 0 2 SHANNON & WILSON, INC. • 400 NORTH 34TH STREET • SUITE 100 • SEATTLE, WASHINGTON • 98103 • MAIN (206) 632-8020 • FAX (206) 695-6777 TEST PIT TP-2F WC % 60 Review By ASTM Std. < 2um % < 20um % 0.6 40 30 0.4 TP-2F, S-11 Gravel Clay-SizeMediumFineCoarse 1 1 / 2 3/4 0.0 3 0.0 1 0.0 0 8 0.0 0 6 0.0 0 4 0.8 21 - 1 - 2 2 0 8 2 - 0 0 3 A _ G S A _ M A I N 2 1 - 2 2 0 8 2 . G P J S H A N _ W I L . G D T 9 / 1 5 / 1 6 21-1-22082-004 APPENDIX C ANALYTICAL LABORATORY TEST RESULTS 21-1-22082-004 APPENDIX D IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL/ENVIRONMENTAL REPORT Page 1 of 2 1/2016 SHANNON & WILSON, INC. Geotechnical and Environmental Consultants Attachment to and part of Report 21-1-22082-004 Date: October 31, 2016 To: Ms. Taine Wilton Edmonds School District #15 IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL/ENVIRONMENTAL REPORT CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND FOR SPECIFIC CLIENTS. Consultants prepare reports to meet the specific needs of specific individuals. A report prepared for a civil engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consultant prepared your report expressly for you and expressly for the purposes you indicated. No one other than you should apply this report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose other than that originally contemplated without first conferring with the consultant. THE CONSULTANT'S REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. A geotechnical/environmental report is based on a subsurface exploration plan designed to consider a unique set of project-specific factors. Depending on the project, these may include: the general nature of the structure and property involved; its size and configuration; its historical use and practice; the location of the structure on the site and its orientation; other improvements such as access roads, parking lots, and underground utilities; and the additional risk created by scope-of-service limitations imposed by the client. To help avoid costly problems, ask the consultant to evaluate how any factors that change subsequent to the date of the report may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used: (1) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking garage, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); (2) when the size, elevation, or configuration of the proposed project is altered; (3) when the location or orientation of the proposed project is modified; (4) when there is a change of ownership; or (5) for application to an adjacent site. Consultants cannot accept responsibility for problems that may occur if they are not consulted after factors which were considered in the development of the report have changed. SUBSURFACE CONDITIONS CAN CHANGE. Subsurface conditions may be affected as a result of natural processes or human activity. Because a geotechnical/environmental report is based on conditions that existed at the time of subsurface exploration, construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the consultant to advise if additional tests are desirable before construction starts; for example, groundwater conditions commonly vary seasonally. Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundwater fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnical/environmental report. The consultant should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary. MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS. Site exploration and testing identifies actual surface and subsurface conditions only at those points where samples are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about overall subsurface conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions in areas not sampled may differ from those predicted in your report. While nothing can be done to prevent such situations, you and your consultant can work together to help reduce their impacts. Retaining your consultant to observe subsurface construction operations can be particularly beneficial in this respect. Page 2 of 2 1/2016 A REPORT'S CONCLUSIONS ARE PRELIMINARY. The conclusions contained in your consultant's report are preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar with the background information needed to determine whether or not the report's recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant who developed your report cannot assume responsibility or liability for the adequacy of the report's recommendations if another party is retained to observe construction. THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnical/environmental report. To help avoid these problems, the consultant should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydrogeological, and environmental findings, and to review the adequacy of their plans and specifications relative to these issues. BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE REPORT. Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnical/environmental reports. These final logs should not, under any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process. To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/environmental report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared, and that developing construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because geotechnical/environmental engineering is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in their contracts, reports, and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the consultant's liabilities to other parties; rather, they are definitive clauses that identify where the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions. The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland Madrona School – Edmonds School District Appendix D Appendix D Hydrogeologic Report By: Shannon & Wilson, Inc. Date: November 29, 2016 Madrona School – Edmonds School District Appendix E Appendix E Wetland and Stream Delineation Report By: Shannon & Wilson, Inc. Date: May 18, 2016 Wetland and Stream Delineation Report New Madrona K-8 Project City of Edmonds, Washington May 18, 2016 Submitted To: Ms. Taine Wilton Edmonds School District #15 20420 68th Avenue West Lynnwood, Washington 98036 By: Shannon & Wilson, Inc. 400 N 34th Street, Suite 100 Seattle, Washington 98103 21-1-22082-002 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 i TABLE OF CONTENTS Page 1.0 INTRODUCTION ..................................................................................................................1 2.0 SITE DESCRIPTION ............................................................................................................1 3.0 METHODS .............................................................................................................................2 4.0 DOCUMENT REVIEW .........................................................................................................3 5.0 WETLAND DELINEATION ................................................................................................3 5.1 Wetland A ..................................................................................................................3 5.2 Wetland B ...................................................................................................................4 5.3 Wetland C ...................................................................................................................5 5.4 Uplands .......................................................................................................................6 6.0 REGULATIONS ....................................................................................................................6 6.1 Federal Regulations ....................................................................................................6 6.2 State Regulations ........................................................................................................7 6.3 City of Edmonds (City) ..............................................................................................8 6.3.1 Wetlands Regulations ..................................................................................8 6.3.2 Other Critical Areas ...................................................................................10 7.0 CLOSURE ............................................................................................................................11 8.0 REFERENCES .....................................................................................................................12 TABLES 1 Wetland Impact Compensatory Mitigation Ratios ..................................................7 2 Required Measures to Minimize Impacts (ECDC 23.50.040(F)(2) .........................8 FIGURES 1 Vicinity Map 2 Wetland Delineation Map TABLE OF CONTENTS (cont.) 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 ii APPENDICES A Wetland Delineation Methodology B Wetland Determination Data Forms – Western Mountains, Valleys, and Coast Region C Wetland Rating Forms – Western Washington D Important Information About Your Wetland Delineation/Mitigation and/or Stream Classification Report 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 1 WETLAND AND STREAM DELINEATION REPORT NEW MADRONA K-8 PROJECT CITY OF EDMONDS, WASHINGTON 1.0 INTRODUCTION Shannon & Wilson, Inc. (Shannon & Wilson) was contracted by the City of Edmonds School District (District) No. 15 to conduct a wetland and stream delineation for the New Madrona K-8 Project, located in Edmonds, Washington (Figure 1). The District plans to construct a new Madrona K-8 school on the south side of the approximately 40-acre property, located at 9300 236th Street SW (Snohomish County tax parcel 27033600404600). The project is located within Section 36 of Township 27 N, Range 4 E, Willamette Meridian. The wetland and stream delineation is intended to assist the District and design team in the site selection and conceptual design process. The scope of services for our wetland and stream delineation was limited to the following tasks:  Conduct a background review of information relating to the site.  Complete a wetland delineation on project site.  Estimate approximate wetland boundaries within 200 feet of the property boundary.  Delineate the ordinary high water mark (OHWM) of onsite streams.  Categorize wetlands using the 2014 Washington State Wetland Rating System for Western Washington.1  Complete a wetland delineation report describing our findings including categories and standard buffer widths. 2.0 SITE DESCRIPTION The approximately 40-acre property is dissected by two steeply sloped wooded areas running in north-south alignments; one is a ravine located along the eastern property boundary and the other is a forested incline located near the middle of the property. The existing Madrona Elementary School is located in the northeast corner of the property and the former Woodway Elementary School is located in the opposite southwest corner of the property. Recreational areas including a track and baseball field, and soccer fields are located in the southeast and northwest corners of the property. The areas surrounding the property consist primarily of residential development. 1 The original scope also included wetland categorization under the 2004 Washington State Wetland Rating System for Western Washington, but a subsequent City critical areas regulations update rendered those forms obsolete and they are not included in this final report. 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 2 The property is well used by local residents for recreation. During our site visits, we observed many people walking dogs in trail systems located throughout the sloped wooded areas as well, as many joggers on the track. A series of catch basin grates were observed along the inside of the track. The survey performed for the property shows that these storm drains, along with storm drain from the existing Madrona Elementary School, discharge to the top of the steep wooded slope in the middle of the property. The survey also identifies storm drain discharges to the top of the wooded ravine located on the eastern property boundary. 3.0 METHODS Shannon & Wilson conducted the wetland delineation fieldwork on July 6 and 7, 2015. Potential wetlands were identified using methods described in the Corps Wetlands Delineation Manual (U.S. Army Corps of Engineers [Corps] Waterways Experiment Station, 1987) and the Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Corps Engineer Research and Development Center, 2010). Potential wetland areas were determined using the triple-parameter approach, which considers vegetation types, soil conditions, and hydrologic conditions. For an area to be considered wetland, it must display each of the following: (a) dominant plant species that are considered hydrophytic by the accepted classification indicators, (b) soils that are considered hydric under federal definition, and (c) indications of wetland hydrology, in accordance with the federal definition. Appendix A provides a detailed description of methodology used. Typically, the OHWM of streams are delineated following the guidance within Ecology’s technical report Determining the Ordinary High Water Mark on Streams in Washington State (Ecology, 2010). However, no onsite streams were observed; therefore, no OHWM delineations occurred. Identified wetlands were delineated by using pink “wetland boundary” flagging and pink pin flags. Data point locations were marked with orange flagging and orange pin flags. 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 3 4.0 DOCUMENT REVIEW Prior to conducting fieldwork, we reviewed the following background information:  U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) Web Soil Survey interactive mapping system  U.S. Fish and Wildlife Service (USFWS) National Wetland Inventory (NWI) Wetlands Mapper interactive mapping system  Washington Department of Fish and Wildlife (WDFW) SalmonScape mapping system  WDFW PHS on the Web interactive mapping system The NRCS web soil survey identifies the site soils as Alderwood gravelly, sandy loam; 15 to 30 percent slopes; Alderwood-Urban land complex; 2 to 8 percent slopes; and 8 to 15 percent slopes (USDA, 2015). These soil series are identified as non-hydric, however they may contain areas of hydric inclusions. Neither the NWI map, the WDFW SalmonScape application, nor the WDFW PHS on the Web application identify streams, wetlands, or other fish and wildlife habitat conservation areas on the property (USFWS, 2015 and WDFW, 2015 and 2016). 5.0 WETLAND DELINEATION Three wetlands (identified as Wetland A, B, and C) were delineated in the project area (Figure 2). Descriptions of the wetland and adjoining uplands follow. Vegetation is described below by common name, with the scientific name and indicator status in parentheses for the first use. Soils are described with the associated Munsell® Color Charts color. Wetlands were characterized according to the updated 2014 version of the “Washington State Wetland Rating System for Western Washington” (Ecology, 2014) as required by the City, Corps, and Ecology (see Appendix B for Wetland Determination Data Forms and Appendix C for Wetland Rating Forms). 5.1 Wetland A Wetland A (approximately 0.02 acre) was delineated on the wooded slope located in the middle of the property, downgradient from storm drain outfalls identified on the survey. A trail system on the slope allows human and pet access to the wetland. Wetland A is classified as a palustrine scrub-shrub wetland according to the Cowardin classification and is a slope wetland according to hydrogeomorphic classification. 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 4 Dominant vegetation in Wetland A includes a shrub strata of salmonberry (Rubus spectabilis, FAC), English laurel (Prunus laurocerasus, NI), mountain ash (Sorbus sitchensis, FAC), as well as an emergent strata of lady fern (Athyrium cyclosorum, FAC) (see Appendix B, Data Sheet DP-7). Soil in Wetland A is generally characterized by a surface horizon of black (10YR 2/1) loam extending to 5 inches below ground surface (bgs), underlain by a grayish brown (10YR 5/2) sand with dark yellowish brown (10YR 4/6) redoximorphic concentrations in the matrix. Soil observed in Wetland A meets the depleted below dark surface (A11) and depleted matrix (F3) hydric soil indicators. During the site visit, seeps were observed throughout Wetland A. Hydrology in Wetland A is likely supported by a combination of storm drain discharges from the upgradient storm drain outfalls and groundwater. Water in the data pit was observed at 11.5 inches bgs and the soil was saturated to the surface. Wetland A was rated according to Ecology’s 2014 wetland rating manual (Ecology, 2014). Wetland A is rated as a Category IV wetland (Appendix C). 5.2 Wetland B Wetland B (approximately 0.4 acre) was delineated within the wooded ravine located on the eastern property boundary. A network of walking paths run adjacent to and through parts of the wetland. Wetland B is classified as a palustrine forested wetland according to the Cowardin classification and as a depressional wetland according to the hydrogeomorphic classification. Dominant vegetation in Wetland B includes a forested strata of western red cedar (Thuja plicata, FAC) and red alder (Alnus rubra, FAC), as well as an emergent strata of slough sedge (Carex obnupta, OBL), yellow-flag iris (Iris pseudocorus, OBL), and reed canarygrass (Phalaris arundinacea, FACW) (see Appendix B, Data Sheet DP-3). Soil in Wetland B is generally characterized by a black (10YR 2/1) silt loam extending to 4 inches bgs underlain by a very dark gray (10YR 3/1) silt loam with gray (10YR 6/1) depletions and dark yellowish brown (10YR 4/6) and grayish brown (10YR 5/2) redoximorphic concentrations extending to 17 inches bgs, underlain by a very dark gray (10YR 3/1) silt loam extending to 18 inches bgs, underlain by a very dark gray (10YR 3/1) silt loam with gray (10YR 6/1) depletions and dark yellowish brown (10YR 4/6) and grayish brown (10YR 5/2) redoximorphic concentrations extending to at least 20 inches bgs. The redoximorphic and depletions observed in the soil below 4 inches bgs appeared blocky and mixed up within the 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 5 matrix suggesting that the soil may have been disturbed in the past. Soils observed in Wetland B meet the redox dark surface (F6) hydric soil indicator. Wetland B is located downgradient of the storm drain outlets associated with the existing Madrona Elementary School and the play fields. Drainage patterns were observed upgradient of Wetland B in the ravine. While these areas showed indication of past surface water flow, they were not dominated by hydric vegetation and did not meet wetland hydric soil indicators. Hydrology in Wetland B is likely predominantly supported by surface flow from the surrounding ravine, the storm drain inputs from the school, and a seasonally high groundwater table. Wetland B was rated according to Ecology’s 2014 wetland rating manual (Ecology, 2014). Wetland B is rated as a Category III wetland (Appendix C). 5.3 Wetland C Wetland C (approximately 0.1 acre) was delineated south of Wetland A along the wooded slope located in the middle of the property, downgradient from the storm drain discharges identified on the survey. A trail system on the slope allows human and pet access to the wetland. Wetland C is classified as a palustrine emergent wetland according to the Cowardin classification and as a slope wetland according to hydrogeomorphic classification. Dominant vegetation in Wetland C includes a shrub strata of western red cedar, an emergent strata of lady fern, and creeping nightshade (Solanum dulcamara, FAC) (see Appendix B, Data Sheet DP-6). Soil in Wetland C is generally characterized by a black (10YR 2/1) loam, underlain by a grayish brown (10YR 5/2), gravelly, loamy sand with dark yellowish brown (10YR 4/4) redoximorphic concentrations in the matrix extending to at least 14 inches bgs. Soils observed in Wetland C meet the depleted below dark surface (A11) and the depleted matrix (F3) hydric soil indicators. During the site visit, seeps were observed throughout Wetland C. Hydrology in Wetland C is likely predominantly supported by a combination of the upgradient storm drain discharges and groundwater. Soil in the data pit was saturated to the surface. Wetland C was rated according to Ecology’s 2014 wetland rating manual (Ecology, 2014). Wetland C is rated as a Category IV wetland (Appendix C). 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 6 5.4 Uplands Uplands observed on the project site consist predominantly of developed school structures and recreational facilities as well as portions of the wooded slope and. The play fields are dominated by a variety of grasses, dandelion (Taraxacum officinale, facultative upland [FACU]), hairy cat’s ear (Hypochaeris radicata, FACU), and clover (Trifolium repens, facultative [FAC]). The wooded areas are dominated by western red cedar, Douglas-fir (Pseudotsuga menziesii, FACU), hemlock (Tsuga heterophylla, FACU), red elderberry (Sambucus racemosa, FACU), holly (Ilex aquifolium, FACU), English laurel, sword fern (Polystichum munitum, FACU), and English ivy (Hedera helix, FACU) (see Appendix B, Data Sheets DP-1, DP-2, DP-4, and DP-5). Upland soils on the property generally consisted of a surface horizon comprised of dark yellowish brown (10YR 3/4) to black (5YR 2.5/1) loam in the upper 2 to 5 inches bgs, underlain by dark yellowish brown (10YR 3/4 and 4/4) to light olive brown (2.5Y 5/3) loamy sand to silt loam extending to at least 16 inches bgs. In areas closer to the wetland boundaries, redoximorphic concentrations were observed below 5 inches. However, the soil profiles in these areas do not meet wetland hydric soil indicators. No saturation was observed in the upland soils although surface drainage patterns were observed in the ravine and below storm drain outfalls on the western slope. 6.0 REGULATIONS Several local, state, and federal regulations apply to development proposals in and/or near wetlands and streams. A summary of applicable regulatory implications is given below. 6.1 Federal Regulations The Corps’ review process under Section 404 of the Clean Water Act (CWA) is required for projects involving discharges of dredges or fill materials into waters of the United States, including non-isolated wetlands and streams. We did not observe a hydrologic surface connection between the onsite wetlands and a Water of the U.S. Therefore, the Corps may consider the onsite wetlands to be isolated and not subject to the CWA. However, this determination would need to be made by the Corps through a “Jurisdictional Determination.” If the Corps takes jurisdiction over the site wetlands, impacts to the wetlands would require compensatory wetland mitigation. The Corps, in cooperation with Ecology, has developed guidance for conducting wetland mitigation in western Washington (Ecology and others, 2006). For unavoidable impacts to Category III and Category IV wetlands, the Corps and Ecology 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 7 recommend the on-site and in-kind permittee-responsible mitigation ratios shown in Table 1 based on area (area of mitigation: area of wetland impact.) TABLE 1 WETLAND IMPACT COMPENSATORY MITIGATION RATIOS Wetland Category Reestablishment or Creation Rehabilitation Reestablishment or Creation (R/C) and Rehabilitation (RH) Reestablishment or Creation (R/C) and Enhancement (E) Enhancement Only III 2:1 4:1 1:1 R/C and 2:1 RH 1:1 R/C and 4:1 E 8:1 IV 1.5:1 3:1 1:1 R/C and 1:1 RH 1:1 R/C and 2:1 E 6:1 6.2 State Regulations Ecology has been authorized to implement Section 401 of the CWA for Water Quality Certification in Washington for most projects that require Corps permits under CWA Section 404. Typically, projects requiring a CWA Section 404 permit also require a CWA Section 401 Water Quality Certification. If the onsite wetlands are determined to be isolated, the project would not require a Section 401 Water Quality Certification. The purpose of the 401 certification process is to ensure that federally permitted or federally funded activities comply with the federal CWA, state water quality laws, and any other applicable state laws. Some general requirements for Section 401, if it is required, include pollution spill prevention and response measures, disposal of excavated or dredged material in upland areas, use of fill material that does not compromise water quality, clear identification of construction boundaries, and provision for site access to the permitting agency for inspection. If the Corps does not take jurisdiction over the onsite wetlands under the CWA, Ecology still has regulatory authority to protect isolated wetlands under the State Water Pollution Control Act (Chapter 90.48 Revised Code of Washington). Ecology would perform an administrative review of the project and would issue an Administrative Order for unavoidable impacts to isolated wetlands. 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 8 6.3 City of Edmonds (City) 6.3.1 Wetlands Regulations The City regulates wetlands and wetland buffers under Chapter 23.50 of the Edmonds Community Development Code (ECDC) (City, 2016).2 Based on our field observations and using the 2014 Wetland Rating System for Western Washington, Wetlands A and C are Category IV wetlands and Wetland B is a Category III wetland (Appendix C). The City requires a 60-foot standard buffer around Category III wetlands and a 40-foot standard buffer around Category IV wetlands, with implementation of the following minimization measures when applicable (Table 2 and Figure 2) (ECDC 23.50.040(F)(1-2)). TABLE 2 REQUIRED MEASURES TO MINMINIZE IMPACTS (ECDC 23.50.040(F)(2)) Disturbance Required Measures to Minimize Impacts Lights Direct lights away from wetland. Noise • Locate activity that generates noise away from wetland. • If warranted, enhance existing buffer with native vegetation plantings adjacent to noise source immediately adjacent to the outer wetland buffer. Toxic runoff • Route all new, untreated runoff away from wetland while ensuring wetland is not dewatered. • Establish covenants limiting use of pesticides within 150 feet of wetlands. • Apply integrated pest management. Stormwater runoff • Retrofit stormwater detention and treatment for roads and existing adjacent development. • Prevent channelized flow from lawns that directly enters the buffer. • Use Low Impact Development (LID) techniques (per Puget Sound Action Team publication on LID techniques). Change in water regime Infiltrate or treat, detain, and disperse into buffer new runoff from impervious surfaces and new lawns. Pets and human disturbance • Use privacy fencing OR plant dense vegetation to delineate buffer edge and to discourage disturbance using vegetation appropriate for the ecoregion. • Place wetland and its buffer in a separate tract or protect with a conservation easement. Dust Use best management practices to control dust. Disruption of corridors or connections • Maintain connections to offsite areas that are undisturbed. • Restore corridors or connections to offsite habitats by replanting. 2 The Edmonds City Council adopted revisions to these regulations in May 2016, so all code references below are taken from the track changes version of the code provided in the Council’s agenda packet. Accordingly, there remain some typographical errors in that version with respect to section numbering. 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 9 In accordance with ECDC 23.50.040(F)(2), the City may require increased buffer widths on a case-by-case basis when a larger buffer is necessary to protect wetland functions and values. The City bases this determination on the following criteria:  A larger buffer is needed to protect other critical areas;  The buffer or adjacent uplands has a slope greater than 15 percent or is susceptible to erosion and standard erosion control measures will not prevent adverse impacts to the wetland;  The buffer area has minimal vegetative cover. In lieu of increasing the buffer width where existing buffer vegetation is inadequate to protect the wetland functions and values, development and implementation of a wetland buffer enhancement plan may substitute.  The wetland and/or buffer is occupied by a federally listed threatened or endangered species, a bald eagle nest, a great blue heron rookery, or a species of local importance; and it is determined by the director that an increased buffer width is necessary to protect the species. ECDC 23.50.040(G) allows for buffer reduction only when existing buffer vegetation is inadequate; the buffers of the existing wetlands are primarily densely vegetated with a mix of native tree and shrub species so this provision may not be applicable. Based on our understanding of the current development proposal, there may be some small areas of existing buffer that are lawn and ballfields that would be impacted. Under ECDC 23.50(G)(3), the City allows for buffer averaging with buffer enhancement if the following requirements are met:  The buffer averaging and enhancement plan provides evidence that wetland functions and values will be: ― Increased or retained through plan implementation for those wetlands where existing buffer vegetation is generally intact; or ― Increased through plan implantation for those wetlands where existing buffer vegetation is inadequate to protect the functions and values of the wetland.  The wetland contains variations in sensitivity due to existing physical characteristics or the character of the buffer varies in slope, soils, or vegetation, and the wetland would benefit from a wider buffer in places and would not be adversely impacted by a narrower buffer in other places;  The total area contained in the buffer area, or the total buffer area existing on a subject parcel for wetlands extending off-site, after averaging is no less than that which would be contained within a standard buffer; and 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 10  The buffer width at any single location is not reduced by more than twenty-five percent (25%) of the standard o buffer width. However, wetland buffer averaging that also modifies the erosion hazard area and/or its buffer would not be allowed by the ECDC without a geotechnical analysis and demonstration that the wetland buffer averaging and erosion or landslide hazard area buffer modification would not adversely impact the wetlands. Wetland buffer reduction through buffer enhancement may also be allowed if buffer averaging is not feasible on site (ECDC 23.50.040(G)(4)). ECDC 23.50.040(G)(8) describes potential permitted uses within wetland buffers, including conservation and restoration activities, passive recreation (such as trails), and stormwater management facilities. The proposed development of a new school and fire access road are not allowed uses within wetland buffers. If buffer averaging or reduction with enhancement is not sufficient to address the need for placement of structures, then a variance and additional buffer mitigation would be required. 6.3.2 Other Critical Areas The City regulates critical areas including wetlands (addressed in Section 6.3.1), fish and wildlife habitat conservation areas, geologically hazardous areas, critical aquifer recharge areas, frequently flooded areas, and shorelines under ECDC Title 23 Natural Resources. Fish and wildlife habitat conservation areas include streams, state priority habitats and areas associated with state priority species, and federally designated threatened or endangered species, among others. The site investigation and document reviews did not identify any streams or other fish and wildlife habitat conservation areas on site or within 225 feet. This scope of services did not include professional assessment of other regulated critical areas. However, some observations about potential geologically hazardous areas is warranted given the affect this critical area can have on site development, particularly when it overlaps with wetlands and wetland buffers. Based on soils mapping, available topographic information, and the City’s definitions of geologically hazardous areas (ECDC 23.80.020), the presence of erosion and/or landslide hazard areas on the eastern and western sides of the property at or near Wetlands A, B, and C and their buffers seems likely. A geotechnical report would be required to establish the appropriate building setback and buffer from the top and toe of any erosion or landslide hazards. An additional analysis would be required to alter the hazard area, the minimum building setback and any required buffer (ECDC 23.80.070(A)(1-2)). A hazards analysis must demonstrate the following: 21-1-22082-002-R1f/wp/lkn 21-1-22082-002 12 8.0 REFERENCES City of Edmonds (Edmonds), 2016, City of Edmonds City Code Chapter 23.50 Wetlands: Edmonds, Wash., May 2016. U.S. Department of Agriculture (USDA), Natural Resources Conservation Service, 2015, Web soil survey. Available: http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm. Accessed: August 2015. U.S. Army Corps of Engineers (Corps) Waterways Experiment Station, 1987, Corps of Engineers wetlands delineation manual: Vicksburg, Miss., U.S. Army Corps of Engineers Waterways Experiment Station, Wetlands Research Program Technical Report Y-87-1, 143 p., available: http://www.wli.nrcs.usda.gov/delineation/. U.S. Army Corps of Engineers (Corps) Engineer Research and Development Center, 2010, Regional supplement to the Corps of Engineers wetland delineation manual: western mountains, valleys, and coast region (version 2.0): Vicksburg, Miss., U.S. Army Corps of Engineers Engineer Research and Development Center, Final report ERDC/EL TR-10-3, 152 p. U.S. Fish and Wildlife Service (USFWS), 2015, Web map service: FWS_Wetlands_WMS: U.S. Fish and Wildlife Service. Open geographical information systems consortium version: 1.3. Available: http://www.fws.gov/wetlands/Data/WebMapServices. Accessed: August 2015. Washington State Department of (Ecology), U.S. Army Corps of Engineers Seattle District, and U.S. Environmental Protection Agency Region 10, 2006, Wetland Mitigation in Washington State – Part 1: Agency Policies and Guidance (Version 1): Olympia, Wash, Washington State Department of Ecology, Publication no. 06-06-11a. Washington State Department of Ecology (Ecology), 2010, Determining the ordinary high water mark on streams in Washington State, second review draft: Lacey, Wash., Washington State Department of Ecology, Publication no. 08-06-001. Washington State Department of Ecology (Ecology), 2014, Washington State wetland rating system for western Washington: Olympia, Wash., Washington State Department of Ecology, Publication no. 14-06-029, 126 p. Washington State Department of Fish and Wildlife (WDFW), 2015, SalmonScape mapping application, accessed July 2015, available: http://apps.wdfw.wa.gov/salmonscape/map.html Washington State Department of Fish and Wildlife (WDFW), 2016, PHS on the Web mapping application, accessed March 2016, available: http://apps.wdfw.wa.gov/phsontheweb/ 104 NE 205th St 238th St SW 236th St SW 240th St SW Lake Ballinger PROJECT LOCATION 99 5 VICINITY MAP FIG. 1 Wetland Delineation Report New Madrona K-8 Project Edmonds, Washington Map adapted from aerial imagery provided by Google Earth Pro, reproduced by permission JUDQWHGE\*RRJOH(DUWK0DSSLQJ6HUYLFH NOTE September 2015 21-1-22082-002 Fi l e n a m e : J : \ 2 1 1 \ 2 2 0 8 2 - 0 0 2 \ 2 1 - 1 - 2 2 0 8 2 - 0 0 2 F i g 1 - V i c m a p . d w g D a t e : 0 9 - 0 2 - 2 0 1 5 L o g i n : S A C Seattle Tacoma Washington Project Location 90 5 MT 97 0 2,000 4,000 Approximate Scale in Feet DP-6 DP-2 DP-7 DP-4 DP-5 DP-3 DP-1 WETLAND DELINEATION MAP FIG. 2 Wetland Delineation Report New Madrona K-8 Project Edmonds, Washington Map adapted from aerial imagery provided by Google Earth Pro, reproduced by permission JUDQWHGE\*RRJOH(DUWK0DSSLQJ6HUYLFH NOTE May 2016 21-1-22082-002 Fi l e n a m e : J: \ 2 1 1 \ 2 2 0 8 2 - 0 0 2 \ 2 1 - 1 - 2 2 0 8 2 - 0 0 2 F i g 2 - S i t e P l a n . d w g D a t e : 05 - 1 8 - 2 0 1 6 L o g i n : ba c MT 0 200 400 Scale in Feet Data Point and Designation Wetland Boundary Wetland Buffer LEGEND WETLAND A CATEGORY IV WETLAND C CATEGORY IV WETLAND B CATEGORY III DP-2 60 Foot Buffer 40 Foot Buffer 21-1-22082-002 APPENDIX A WETLAND DELINEATION METHODOLOGY AppendixA_Methodology (Western Mtns) Dec 2012/ 21-1-22082-002 A-i APPENDIX A WETLAND DELINEATION METHODOLOGY TABLE OF CONTENTS Page A.1 WETLAND VEGETATION .......................................................................................... A-1 A.2 HYDRIC SOILS ............................................................................................................. A-3 A.3 WETLAND HYDROLOGY .......................................................................................... A-3 A.4 DISCLAIMER ................................................................................................................ A-4 A.5 REFERENCES ............................................................................................................... A-4 TABLE A-1 Definitions of Plant Indicator Status ................................................................... A-2 AppendixA_Methodology (Western Mtns) Dec 2012/ 21-1-22082-002 A-1 APPENDIX A WETLAND DELINEATION METHODOLOGY The triple-parameter approach, as required in the Washington State Department of Ecology’s (Ecology’s) 1997 Washington State Wetlands Identification and Delineation Manual, the United States Army Corps of Engineers’ (the Corps’) 1987 Corps of Engineers Wetland Delineation Manual, and the Corps’ 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0) was used to identify and delineate the wetlands on the site described in this report. The triple-parameter approach requires that vegetation, soils, and hydrology are each evaluated to determine the presence or absence of wetlands. An area is considered to be a wetland if each of the following is met: (a) dominant hydrophytic vegetation is present in the area, (b) the soils in the area are hydric, and (c) the necessary hydrologic conditions within the area are met. A determination of wetland presence was made by conducting a Routine Delineation. Corresponding upland and wetland plots were recorded to characterize surface and subsurface conditions and more accurately determine the boundaries of on-site wetlands. A.1 WETLAND VEGETATION Hydrophytic plants are plant species specially adapted for saturated and/or anaerobic conditions. These species can be found in areas where there is a significant duration and frequency of inundation, which produces permanently or periodically saturated soils. Hydrophytic species, due to morphological, physiological, and reproductive adaptations, have the ability to grow, effectively compete, reproduce, and thrive in anaerobic soil. Indicators of hydrophytic vegetation are based on the wetland indicator status of plant species on the national wetland plant list (Lichvar, 2012). Plants are categorized as Obligate (OBL), Facultative Wetland (FACW), Facultative (FAC), Facultative Upland (FACU), or Upland (UPL). Species in the facultative categories (FACW, FAC, and FACU) are recognized as occurring in both wetlands and non- wetlands to varying degrees. Most wetlands are dominated mainly by species rated as OBL, FACW, or FAC (Table A-1). AppendixA_Methodology (Western Mtns) Dec 2012/ 21-1-22082-002 A-2 TABLE A-1 PLANT INDICATOR STATUS GROUPS Plant Indicator Status Categories Obligate Wetland (OBL) – Plants that almost always occur in wetlands. Facultative Wetland (FACW) – Plants that usually occur in wetlands, but may occur in non-wetlands. Facultative (FAC) – Plants that occur in wetlands or non-wetlands. Facultative Upland (FACU) – Plants that usually occur in non-wetlands, but may occur in wetlands. Obligate Upland (UPL) – Plants that almost never occur in wetlands. (Lichvar, 2012) The approximate percentage of absolute cover for each of the different plant species occurring within the tree, sapling/shrub, woody vine, and herbaceous strata was determined. Trees within a 30-foot radius; sapling/shrubs and woody vines within a 15-foot radius; and herbaceous species within a 5-foot radius of each data point were identified and noted. However, where site conditions merited it, the dimensions of the tree, sapling/shrub, woody vine, and herbaceous strata were modified. The dominance test is the primary hydrophytic vegetation indicator and it is used in all wetland delineations. Dominant plant species are considered to be those that, when cumulatively totaled in descending order of absolute percent cover, exceed 50 percent of the total absolute cover for each vegetative stratum. Any additional species individually representing 20 percent or greater of the total absolute cover for each vegetative strata are also considered dominant. Hydrophytic vegetation is considered to be present when greater than 50 percent of the dominant plant species within the area had an indicator status of OBL, FACW, or FAC. If a plant community does not meet the dominance test in areas where hydric soils and wetland hydrology are present, vegetation is reevaluated using the prevalence index, plant morphological adaptations for living in wetlands, and/or abundance of bryophytes (e.g., mosses) adapted to living in wetlands. The prevalence index is a weighted average that takes into account the abundance of all plant species within the sampling area to determine if hydrophytic vegetation is more or less prevalent. Using the prevalence index, all plants within the sampling area are grouped by wetland indicator status and absolute percent cover is summed for each group. Total cover for each indicator status group is weighted by the following multipliers: OBL=1, FACW=2, FAC=3, FACU=4, UPL=5. The prevalence index is calculated by dividing the sum of the weighted totals by the sum of total cover in the sampling area. A prevalence index of 3.0 or less indicates that hydrophytic vegetation is present. AppendixA_Methodology (Western Mtns) Dec 2012/ 21-1-22082-002 A-3 A.2 HYDRIC SOILS Hydric soils are defined as soils that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part (USDA SCS, 1994). Repeated periods of saturation and inundation for more than a few days, in combination with soil microbial activity, causes depletion in oxygen (anaerobic conditions) and results in delayed decomposition of organic matter and reduction of iron, manganese, and sulfur elements. As a result of these processes, most hydric soils develop distinctive characteristics observable in the field during both wet and dry periods. (USDA NRCS, 2010). These characteristics may be exhibited as an accumulation of organic matter; bluish-gray, green-gray, or low chroma and high value soil colors; mottling or other concentrations of iron and manganese; and/or hydrogen sulfide odor similar to a rotten egg smell. The USDA Natural Resources Conservation Service (NRCS) has developed official hydric soil indicators as summarized in Field Indicators of Hydric Soils in the United States (USDA NRCS, 2010). These indicators were developed to assist in delineation of hydric soils and are based predominantly on hydric soils near the margins of wetlands. Some hydric soils, including soils within the wettest parts of wetlands, may lack any of the approved hydric soil indicators. If a hydric soil indicator is present, the soil is determined to be hydric. If no hydric soil indicator is present, additional site information is used to assess whether the soil meets the definition of hydric soil. Identification of hydric soils was aided through observation of surface hydrologic characteristics and indicators of wetland hydrology (e.g., drainage patterns). Soil characteristics were observation at several data points, placed both inside and outside the wetland. Holes were dug with a shovel to the depth needed to document an indicator or to confirm the absence of hydric soil indicators. Soil organic content was estimated visually and texturally. Soil colors were examined in the field immediately after sampling. Dry soils were moistened. Soil colors were determined through analysis of the hue, value, and chroma best represented in the Munsell® Soil Color Chart. A.3 WETLAND HYDROLOGY Wetland hydrology is determined by observable evidence that inundation or soil saturation have occurred during a significant portion of the growing season repeatedly over a period of years so that wet condition have been sufficient to produce wetland vegetation and hydric soils. Wetland hydrology indicators give evidence of a continuing wetland hydrologic regime. Wetland hydrology criteria were considered to be satisfied if it appeared that wetland hydrology was AppendixA_Methodology (Western Mtns) Dec 2012/ 21-1-22082-002 A-4 present for at least 5 to 12.5 percent (12 to 31 days) of the growing season. The growing season in western Washington is typically considered to be from March 1 to October 31 (244 days). However, the growing season is considered to have begun when: (a) evidence of plant growth has begun on two non-evergreen vascular plants, and (b) the soil reaches a temperature of 41 degrees Fahrenheit at 12 inches. The Seattle District Corps of Engineers requires 14 consecutive days of inundation or saturation for a wetland hydrology to be considered present. Wetland hydrology was evaluated by direct visual observation of surface inundation or soil saturation in data plots. The area near each data point was examined for indicators of wetland hydrology. Wetland hydrology indicators are categorized as primary or secondary based on their estimated reliability. Wetland hydrology was considered present if there was evidence of one primary indicator or at least two secondary indicators. Some primary indicators include surface water, a shallow water table or saturated soils observed within 12 inches of the surface, dried watermarks, drift lines, sediment deposits, water-stained leaves, and algal mat/crust. Some secondary indicators include a water table within 12 to 24 inches of the surface during the dry season; drainage patterns; a landscape position in a depression, drainage, or fringe of a water body; and a shallow restrictive layer capable of perching water within 12 inches of the surface. A.4 DISCLAIMER This methodology was prepared for reference use only and is not intended to replace Ecology’s 1997 Washington State Wetlands Identification and Delineation Manual, the 1987 Corps of Engineers Wetland Delineation Manual, or the Corps’ 2010 Regional Supplement to the Corps of Engineers Wetland Delineation Manual: Western Mountains, Valleys, and Coast Region (Version 2.0). A.5 REFERENCES Munsell Color, 1992, Munsell soil color charts: Newburgh, N.Y., Macbeth Division of Kollmorgen Instruments Corporation, 1 v. Lichvar, R. W., 2012, The national wetland plant list: U. S. Army Corps of Engineers Engineer Research and Development Center, Report ERDCC/CRREL TR-12-11, 224 p., available: http://rsgisias.crrel.usace.army.mil/NWPL/doc/proc 2012/ERDC-CRREL TR-12-11 NWPL 2012.pdf. AppendixA_Methodology (Western Mtns) Dec 2012/ 21-1-22082-002 A-5 U.S. Army Corps of Engineers Engineer Research and Development Center, 2010, Regional supplement to the Corps of Engineers wetlands delineation manual: western mountains, valleys and coast region, Version 2.0: Vicksburg, Miss., U. S. Army Corps of Engineers Engineer Research and Development Center, Report ERDC/EL TR-10-3, 153 p. U.S. Army Corps of Engineers Waterways Experiment Station, 1987, Corps of Engineers wetlands delineation manual: Vicksburg, Miss., U.S. Army Corps of Engineers Waterways Experiment Station, Wetlands Research Program Technical Report Y-87-1, 143 p., available: http://www.wli.nrcs.usda.gov/delineation/. U.S. Department of Agriculture (USDA) Soil Conservation Service (SCS), 1994, Changes in hydric soils of the United States: Washington, D.C., Office of the Federal Register, FR 59 (133): 35680-35681, July 13. U.S. Department of Agriculture (USDA) Natural Resources Conservation Services (NRCS), 2010, Field indicators of hydric soils in the United States, Version 7.0, L.M. Vasilas, G.W. Hurt, and C.V. Noble (eds.), USDA, NRCS, in cooperation with the National Technical Committee for Hydric Soils. Washington State Department of Ecology, 1997, Washington state wetlands identification and delineation manual: Olympia, Wash., Washington State Department of Ecology, Report 96-94. 21-1-22082-002 APPENDIX B WETLAND DETERMINATION DATA FORMS – WESTERN MOUNTAINS, VALLEYS, AND COAST REGION 21-1-22082-002 APPENDIX C WETLAND RATING FORMS – WESTERN WASHINGTON Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 1 Rating Form – Effective January 1, 2015 Score for each function based on three ratings (order of ratings is not important) 9 = H,H,H 8 = H,H,M 7 = H,H,L 7 = H,M,M 6 = H,M,L 6 = M,M,M 5 = H,L,L 5 = M,M,L 4 = M,L,L 3 = L,L,L RATING SUMMARY – Western Washington Name of wetland (or ID #): _________________________________ Date of site visit: _____ Rated by____________________________ Trained by Ecology?__ Yes ___No Date of training______ HGM Class used for rating_________________ Wetland has multiple HGM classes?___Y ____N NOTE: Form is not complete without the figures requested (figures can be combined). Source of base aerial photo/map ______________________________________ OVERALL WETLAND CATEGORY ____ (based on functions___ or special characteristics___) 1.Category of wetland based on FUNCTIONS _______Category I – Total score = 23 - 27 _______Category II – Total score = 20 - 22 _______Category III – Total score = 16 - 19 _______Category IV – Total score = 9 - 15 FUNCTION Improving Water Quality Hydrologic Habitat Circle the appropriate ratings Site Potential H M L H M L H M L Landscape Potential H M L H M L H M L Value H M L H M L H M L TOTAL Score Based on Ratings 2.Category based on SPECIAL CHARACTERISTICS of wetland CHARACTERISTIC CATEGORY Estuarine I II Wetland of High Conservation Value I Bog I Mature Forest I Old Growth Forest I Coastal Lagoon I II Interdunal I II III IV None of the above A Wetland A 7/6 and 7/7/15 S. Corbin (PWS)X 10/09 and 10/14 XSlope Google Earth X 445 13 X IV 10/09 and 5/14 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 2 Rating Form – Effective January 1, 2015 Maps and figures required to answer questions correctly for Western Washington Depressional Wetlands Map of: To answer questions: Figure # Cowardin plant classes D 1.3, H 1.1, H 1.4 Hydroperiods D 1.4, H 1.2 Location of outlet (can be added to map of hydroperiods) D 1.1, D 4.1 Boundary of area within 150 ft of the wetland (can be added to another figure) D 2.2, D 5.2 Map of the contributing basin D 4.3, D 5.3 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) D 3.1, D 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) D 3.3 Riverine Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Ponded depressions R 1.1 Boundary of area within 150 ft of the wetland (can be added to another figure) R 2.4 Plant cover of trees, shrubs, and herbaceous plants R 1.2, R 4.2 Width of unit vs. width of stream (can be added to another figure) R 4.1 Map of the contributing basin R 2.2, R 2.3, R 5.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) R 3.1 Screen capture of list of TMDLs for WRIA in which unit is found (from web) R 3.2, R 3.3 Lake Fringe Wetlands Map of: To answer questions: Figure # Cowardin plant classes L 1.1, L 4.1, H 1.1, H 1.4 Plant cover of trees, shrubs, and herbaceous plants L 1.2 Boundary of area within 150 ft of the wetland (can be added to another figure) L 2.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) L 3.1, L 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) L 3.3 Slope Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Plant cover of dense trees, shrubs, and herbaceous plants S 1.3 Plant cover of dense, rigid trees, shrubs, and herbaceous plants (can be added to figure above) S 4.1 Boundary of 150 ft buffer (can be added to another figure) S 2.1, S 5.1 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) S 3.1, S 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) S 3.3 A 1 1 1 1 1 2 3 4 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 3 Rating Form – Effective January 1, 2015 HGM Classification of Wetlands in Western Washington 1.Are the water levels in the entire unit usually controlled by tides except during floods? NO – go to 2 YES – the wetland class is Tidal Fringe – go to 1.1 1.1 Is the salinity of the water during periods of annual low flow below 0.5 ppt (parts per thousand)? NO – Saltwater Tidal Fringe (Estuarine) YES – Freshwater Tidal Fringe If your wetland can be classified as a Freshwater Tidal Fringe use the forms for Riverine wetlands. If it is Saltwater Tidal Fringe it is an Estuarine wetland and is not scored. This method cannot be used to score functions for estuarine wetlands. 2.The entire wetland unit is flat and precipitation is the only source (>90%) of water to it. Groundwater and surface water runoff are NOT sources of water to the unit. NO – go to 3 YES – The wetland class is Flats If your wetland can be classified as a Flats wetland, use the form for Depressional wetlands. 3.Does the entire wetland unit meet all of the following criteria? ___The vegetated part of the wetland is on the shores of a body of permanent open water (without any plants on the surface at any time of the year) at least 20 ac (8 ha) in size; ___At least 30% of the open water area is deeper than 6.6 ft (2 m). NO – go to 4 YES – The wetland class is Lake Fringe (Lacustrine Fringe) 4.Does the entire wetland unit meet all of the following criteria? ____The wetland is on a slope (slope can be very gradual), ____The water flows through the wetland in one direction (unidirectional) and usually comes from seeps. It may flow subsurface, as sheetflow, or in a swale without distinct banks, ____The water leaves the wetland without being impounded. NO – go to 5 YES – The wetland class is Slope NOTE: Surface water does not pond in these type of wetlands except occasionally in very small and shallow depressions or behind hummocks (depressions are usually <3 ft diameter and less than 1 ft deep). 5.Does the entire wetland unit meet all of the following criteria? ____The unit is in a valley, or stream channel, where it gets inundated by overbank flooding from that stream or river, ____The overbank flooding occurs at least once every 2 years. For questions 1-7, the criteria described must apply to the entire unit being rated. If the hydrologic criteria listed in each question do not apply to the entire unit being rated, you probably have a unit with multiple HGM classes. In this case, identify which hydrologic criteria in questions 1-7 apply, and go to Question 8. A X X X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 4 Rating Form – Effective January 1, 2015 NO – go to 6 YES – The wetland class is Riverine NOTE: The Riverine unit can contain depressions that are filled with water when the river is not flooding 6. Is the entire wetland unit in a topographic depression in which water ponds, or is saturated to the surface, at some time during the year? This means that any outlet, if present, is higher than the interior of the wetland. NO – go to 7 YES – The wetland class is Depressional 7.Is the entire wetland unit located in a very flat area with no obvious depression and no overbank flooding? The unit does not pond surface water more than a few inches. The unit seems to be maintained by high groundwater in the area. The wetland may be ditched, but has no obvious natural outlet. NO – go to 8 YES – The wetland class is Depressional 8.Your wetland unit seems to be difficult to classify and probably contains several different HGM classes. For example, seeps at the base of a slope may grade into a riverine floodplain, or a small stream within a Depressional wetland has a zone of flooding along its sides. GO BACK AND IDENTIFY WHICH OF THE HYDROLOGIC REGIMES DESCRIBED IN QUESTIONS 1-7 APPLY TO DIFFERENT AREAS IN THE UNIT (make a rough sketch to help you decide). Use the following table to identify the appropriate class to use for the rating system if you have several HGM classes present within the wetland unit being scored. NOTE: Use this table only if the class that is recommended in the second column represents 10% or more of the total area of the wetland unit being rated. If the area of the HGM class listed in column 2 is less than 10% of the unit; classify the wetland using the class that represents more than 90% of the total area. HGM classes within the wetland unit being rated HGM class to use in rating Slope + Riverine Riverine Slope + Depressional Depressional Slope + Lake Fringe Lake Fringe Depressional + Riverine along stream within boundary of depression Depressional Depressional + Lake Fringe Depressional Riverine + Lake Fringe Riverine Salt Water Tidal Fringe and any other class of freshwater wetland Treat as ESTUARINE If you are still unable to determine which of the above criteria apply to your wetland, or if you have more than 2 HGM classes within a wetland boundary, classify the wetland as Depressional for the rating. A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 11 Rating Form – Effective January 1, 2015 SLOPE WETLANDS Water Quality Functions - Indicators that the site functions to improve water quality S 1.0. Does the site have the potential to improve water quality? S 1.1. Characteristics of the average slope of the wetland: (a 1% slope has a 1 ft vertical drop in elevation for every 100 ft of horizontal distance) Slope is 1% or less points = 3 Slope is > 1%-2% points = 2 Slope is > 2%-5% points = 1 Slope is greater than 5% points = 0 S 1.2. The soil 2 in below the surface (or duff layer) is true clay or true organic (use NRCS definitions): Yes = 3 No = 0 S 1.3. Characteristics of the plants in the wetland that trap sediments and pollutants: Choose the points appropriate for the description that best fits the plants in the wetland. Dense means you have trouble seeing the soil surface (>75% cover), and uncut means not grazed or mowed and plants are higher than 6 in. Dense, uncut, herbaceous plants > 90% of the wetland area points = 6 Dense, uncut, herbaceous plants > ½ of area points = 3 Dense, woody, plants > ½ of area points = 2 Dense, uncut, herbaceous plants > ¼ of area points = 1 Does not meet any of the criteria above for plants points = 0 Total for S 1 Add the points in the boxes above Rating of Site Potential If score is: 12 = H 6-11 = M 0-5 = L Record the rating on the first page S 2.0. Does the landscape have the potential to support the water quality function of the site? S 2.1. Is > 10% of the area within 150 ft on the uphill side of the wetland in land uses that generate pollutants? Yes = 1 No = 0 S 2.2. Are there other sources of pollutants coming into the wetland that are not listed in question S 2.1? Other sources ________________ Yes = 1 No = 0 Total for S 2 Add the points in the boxes above Rating of Landscape Potential If score is: 1-2 = M 0 = L Record the rating on the first page S 3.0. Is the water quality improvement provided by the site valuable to society? S 3.1. Does the wetland discharge directly (i.e., within 1 mi) to a stream, river, lake, or marine water that is on the 303(d) list? Yes = 1 No = 0 S 3.2. Is the wetland in a basin or sub-basin where water quality is an issue? At least one aquatic resource in the basin is on the 303(d) list. Yes = 1 No = 0 S 3.3. Has the site been identified in a watershed or local plan as important for maintaining water quality? Answer YES if there is a TMDL for the basin in which unit is found. Yes = 2 No = 0 Total for S 3 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page X 0 0 2 2 X 1 dog walkers/ dog poop 1 2 X 0 1 0 1 XX 31 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 12 Rating Form – Effective January 1, 2015 SLOPE WETLANDS Hydrologic Functions - Indicators that the site functions to reduce flooding and stream erosion S 4.0. Does the site have the potential to reduce flooding and stream erosion? S 4.1. Characteristics of plants that reduce the velocity of surface flows during storms: Choose the points appropriate for the description that best fits conditions in the wetland. Stems of plants should be thick enough (usually > 1/8 in), or dense enough, to remain erect during surface flows . Dense, uncut, rigid plants cover > 90% of the area of the wetland points = 1 All other conditions points = 0 Rating of Site Potential If score is: 1 = M 0 = L Record the rating on the first page S 5.0. Does the landscape have the potential to support the hydrologic functions of the site? S 5.1. Is more than 25% of the area within 150 ft upslope of wetland in land uses or cover that generate excess surface runoff? Yes = 1 No = 0 Rating of Landscape Potential If score is: 1 = M 0 = L Record the rating on the first page S 6.0. Are the hydrologic functions provided by the site valuable to society? S 6.1. Distance to the nearest areas downstr eam that have flooding problems: The sub-basin immediately down-gradient of site has flooding problems that result in damage to human or natural resources (e.g., houses or salmon redds) points = 2 Surface flooding problems are in a sub-basin farther down-gradient points = 1 No flooding problems anywhere downstream points = 0 S 6.2. Has the site been identified as important for flood storage or flood conveyance in a regional flood control plan? Yes = 2 No = 0 Total for S 6 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page NOTES and FIELD OBSERVATIONS: A 0 X 0 X 1 0 1 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 13 Rating Form – Effective January 1, 2015 These questions apply to wetlands of all HGM classes. HABITAT FUNCTIONS - Indicators that site functions to provide important habitat H 1.0. Does the site have the potential to provide habitat? H 1.1. Structure of plant community: Indicators are Cowardin classes and strata within the Forested class. Check the Cowardin plant classes in the wetland. Up to 10 patches may be combined for each class to meet the threshold of ¼ ac or more than 10% of the unit if it is smaller than 2.5 ac. Add the number of structures checked. ____Aquatic bed 4 structures or more: points = 4 ____Emergent 3 structures: points = 2 ____Scrub-shrub (areas where shrubs have > 30% cover) 2 structures: points = 1 ____Forested (areas where trees have > 30% cover) 1 structure: points = 0 If the unit has a Forested class, check if: ____The Forested class has 3 out of 5 strata (canopy, sub-canopy, shrubs, herbaceous, moss/ground-cover) that each cover 20% within the Forested polygon H 1.2. Hydroperiods Check the types of water regimes (hydroperiods) present within the wetland. The water regime has to cover more than 10% of the wetland or ¼ ac to count (see text for descriptions of hydroperiods). ____Permanently flooded or inundated 4 or more types present: points = 3 ____Seasonally flooded or inundated 3 types present: points = 2 ____Occasionally flooded or inundated 2 types present: points = 1 ____Saturated only 1 type present: points = 0 ____Permanently flowing stream or river in, or adjacent to, the wetland ____Seasonally flowing stream in, or adjacent to, the wetland ____Lake Fringe wetland 2 points ____Freshwater tidal wetland 2 points H 1.3. Richness of plant species Count the number of plant species in the wetland that cover at least 10 ft 2. Different patches of the same species can be combined to meet the size threshold and you do not have to name the species. Do not include Eurasian milfoil, reed canarygrass, purple loosestrife, Canadian thistle If you counted: > 19 species points = 2 5 - 19 species points = 1 < 5 species points = 0 H 1.4. Interspersion of habitats Decide from the diagrams below whether interspersion among Cowardin plants classes (described in H 1.1), or the classes and unvegetated areas (can include open water or mudflats) is high, moderate, low, or none. If you have four or more plant classes or three classes and open water, the rating is always high. None = 0 points Low = 1 point Moderate = 2 points All three diagrams in this row are HIGH = 3points A X 0 X 0 1 0 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 14 Rating Form – Effective January 1, 2015 H 1.5. Special habitat features: Check the habitat features that are present in the wetland. The number of checks is the number of points. ____Large, downed, woody debris within the wetland (> 4 in diameter and 6 ft long). ____Standing snags (dbh > 4 in) within the wetland ____Undercut banks are present for at least 6.6 ft (2 m) and/or overhanging plants extends at least 3.3 ft (1 m) over a stream (or ditch) in, or contiguous with the wetland, for at least 33 ft (10 m) ____Stable steep banks of fine material that might be used by beaver or muskrat for denning (> 30 degree slope) OR signs of recent beaver activity are present (cut shrubs or trees that have not yet weathered where wood is exposed) ____At least ¼ ac of thin-stemmed persistent plants or woody branches are present in areas that are permanently or seasonally inundated (structures for egg-laying by amphibians) ____Invasive plants cover less than 25% of the wetland area in every stratum of plants (see H 1.1 for list of strata) Total for H 1 Add the points in the boxes above Rating of Site Potential If score is: 15-18 = H 7-14 = M 0-6 = L Record the rating on the first page H 2.0. Does the landscape have the potential to support the habitat functions of the site? H 2.1. Accessible habitat (include only habitat that directly abuts wetland unit). Calculate: % undisturbed habitat + [(% moderate and low intensity land uses)/2] = _______% If total accessible habitat is: > 1/3 (33.3%) of 1 km Polygon points = 3 20-33% of 1 km Polygon points = 2 10-19% of 1 km Polygon points = 1 < 10% of 1 km Polygon points = 0 H 2.2. Undisturbed habitat in 1 km Polygon around the wetland. Calculate: % undisturbed habitat + [(% moderate and low intensity land uses)/2] = _______% Undisturbed habitat > 50% of Polygon points = 3 Undisturbed habitat 10-50% and in 1-3 patches points = 2 Undisturbed habitat 10-50% and > 3 patches points = 1 Undisturbed habitat < 10% of 1 km Polygon points = 0 H 2.3. Land use intensity in 1 km Polygon: If > 50% of 1 km Polygon is high intensity land use points = (- 2) ≤ 50% of 1 km Polygon is high intensity points = 0 Total for H 2 Add the points in the boxes above Rating of Landscape Potential If score is: 4-6 = H 1-3 = M < 1 = L Record the rating on the first page H 3.0. Is the habitat provided by the site valuable to society? H 3.1. Does the site provide habitat for species valued in laws, regulations, or policies? Choose only the highest score that applies to the wetland being rated. Site meets ANY of the following criteria: points = 2  It has 3 or more priority habitats within 100 m (see next page)  It provides habitat for Threatened or Endangered species (any plant or animal on the state or federal lists)  It is mapped as a location for an individual WDFW priority species  It is a Wetland of High Conservation Value as determined by the Department of Natural Resources  It has been categorized as an important habitat site in a local or regional comprehensive plan, in a Shoreline Master Plan, or in a watershed plan Site has 1 or 2 priority habitats (listed on next page) within 100 m points = 1 Site does not meet any of the criteria above points = 0 Rating of Value If score is: 2 = H 1 = M 0 = L Record the rating on the first page A X 1 2 X 0 0 0 0 0 0 0 0 -2 -2 X 1 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 15 Rating Form – Effective January 1, 2015 WDFW Priority Habitats Priority habitats listed by WDFW (see complete descriptions of WDFW priority habitats, and the counties in which they can be found, in: Washington Department of Fish and Wildlife. 2008. Priority Habitat and Species List. Olympia, Washington. 177 pp. http://wdfw.wa.gov/publications/00165/wdfw00165.pdf or access the list from here: http://wdfw.wa.gov/conservation/phs/list/) Count how many of the following priority habitats are within 330 ft (100 m) of the wetland unit: NOTE: This question is independent of the land use between the wetland unit and the priority habitat.  Aspen Stands: Pure or mixed stands of aspen greater than 1 ac (0.4 ha).  Biodiversity Areas and Corridors: Areas of habitat that are relatively important to various species of native fish and wildlife (full descriptions in WDFW PHS report).  Herbaceous Balds: Variable size patches of grass and forbs on shallow soils over bedrock.  Old-growth/Mature forests: Old-growth west of Cascade crest – Stands of at least 2 tree species, forming a multi- layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha ) > 32 in (81 cm) dbh or > 200 years of age. Mature forests – Stands with average diameters exceeding 21 in (53 cm) dbh; crown cover may be less than 100%; decay, decadence, numbers of snags, and quantity of large downed material is generally less than that found in old-growth; 80-200 years old west of the Cascade crest.  Oregon White Oak: Woodland stands of pure oak or oak/conifer associations where canopy coverage of the oak component is important (full descriptions in WDFW PHS report p. 158 – see web link above).  Riparian: The area adjacent to aquatic systems with flowing water that contains elements of both aquatic and terrestrial ecosystems which mutually influence each other.  Westside Prairies: Herbaceous, non-forested plant communities that can either take the form of a dry prairie or a wet prairie (full descriptions in WDFW PHS report p. 161 – see web link above).  Instream: The combination of physical, biological, and chemical processes and conditions that interact to provide functional life history requirements for instream fish and wildlife resources.  Nearshore: Relatively undisturbed nearshore habitats. These include Coastal Nearshore, Open Coast Nearshore, and Puget Sound Nearshore. (full descriptions of habitats and the definition of relatively undisturbed are in WDFW report – see web link on previous page).  Caves: A naturally occurring cavity, recess, void, or system of interconnected passages under the earth in soils, rock, ice, or other geological formations and is large enough to contain a human.  Cliffs: Greater than 25 ft (7.6 m) high and occurring below 5000 ft elevation.  Talus: Homogenous areas of rock rubble ranging in average size 0.5 - 6.5 ft (0.15 - 2.0 m), composed of basalt, andesite, and/or sedimentary rock, including riprap slides and mine tailings. May be associated with cliffs.  Snags and Logs: Trees are considered snags if they are dead or dying and exhibit sufficient decay characteristics to enable cavity excavation/use by wildlife. Priority snags have a diameter at breast height of > 20 in (51 cm) in western Washington and are > 6.5 ft (2 m) in height. Priority logs are > 12 in (30 cm) in diameter at the largest end, and > 20 ft (6 m) long. Note: All vegetated wetlands are by definition a priority habitat but are not included in this list because they are addressed elsewhere. A X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 16 Rating Form – Effective January 1, 2015 CATEGORIZATION BASED ON SPECIAL CHARACTERISTICS Wetland Type Check off any criteria that apply to the wetland. Circle the category when the appropriate criteria are met. Category SC 1.0. Estuarine wetlands Does the wetland meet the following criteria for Estuarine wetlands?  The dominant water regime is tidal,  Vegetated, and  With a salinity greater than 0.5 ppt Yes –Go to SC 1.1 No= Not an estuarine wetland SC 1.1. Is the wetland within a National Wildlife Refuge, National Park, National Estuary Reserve, Natural Area Preserve, State Park or Educational, Environmental, or Scientific Reserve designated under WAC 332 -30-151? Yes = Category I No - Go to SC 1.2 Cat. I SC 1.2. Is the wetland unit at least 1 ac in size and meets at least two of the following three conditions?  The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing, and has less than 10% cover of non-native plant species. (If non-native species are Spartina, see page 25)  At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-grazed or un- mowed grassland.  The wetland has at least two of the following features: tidal channels, depressions with open water, or contiguous freshwater wetlands. Yes = Category I No = Category II Cat. I Cat. II SC 2.0. Wetlands of High Conservation Value (WHCV) SC 2.1. Has the WA Department of Natural Resources updated their website to include the list of Wetlands of High Conservation Value? Yes – Go to SC 2.2 No – Go to SC 2.3 SC 2.2. Is the wetland listed on the WDNR database as a Wetland of High Conservation Value? Yes = Category I No = Not a WHCV SC 2.3. Is the wetland in a Section/Township/Range that contains a Natural Heritage wetland? http://www1.dnr.wa.gov/nhp/refdesk/datasearch/wnhpwetlands.pdf Yes – Contact WNHP/WDNR and go to SC 2.4 No = Not a WHCV SC 2.4. Has WDNR identified the wetland within the S/T/R as a Wetland of High Conservation Value and listed it on their website? Yes = Category I No = Not a WHCV Cat. I SC 3.0. Bogs Does the wetland (or any part of the unit) meet both the criteria for soils and vegetation in bogs? Use the key below. If you answer YES you will still need to rate the wetland based on its functions. SC 3.1. Does an area within the wetland unit have organic soil horizons, either peats or mucks, that compose 16 in or more of the first 32 in of the soil profile? Yes – Go to SC 3.3 No – Go to SC 3.2 SC 3.2. Does an area within the wetland unit have organic soils, either peats or mucks, that are less than 16 in deep over bedrock, or an impermeable hardpan such as clay or volcanic ash, or that are floating on top of a lake or pond? Yes – Go to SC 3.3 No = Is not a bog SC 3.3. Does an area with peats or mucks have more than 70% cover of mosses at ground level, AND at least a 30% cover of plant species listed in Table 4? Yes = Is a Category I bog No – Go to SC 3.4 NOTE: If you are uncertain about the extent of mosses in the understory , you may substitute that criterion by measuring the pH of the water that seeps into a hole dug at least 16 in deep. If the pH is less than 5.0 and the plant species in Table 4 are present, the wetland is a bog. SC 3.4. Is an area with peats or mucks forested (> 30% cover) with Sitka spruce, subalpine fir, western red cedar, western hemlock, lodgepole pine, quaking aspen, Engelmann spruce, or western white pine, AND any of the species (or combination of species) listed in Table 4 provide more than 30% of the cover under the canopy? Yes = Is a Category I bog No = Is not a bog Cat. I A Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 17 Rating Form – Effective January 1, 2015 SC 4.0. Forested Wetlands Does the wetland have at least 1 contiguous acre of forest that meets one of these criteria for the WA Department of Fish and Wildlife’s forests as priority habitats? If you answer YES you will still need to rate the wetland based on its functions.  Old-growth forests (west of Cascade crest): Stands of at least two tree species, forming a multi-layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha) that are at least 200 years of age OR have a diameter at breast height (dbh) of 32 in (81 cm) or more.  Mature forests (west of the Cascade Crest): Stands where the largest trees are 80- 200 years old OR the species that make up the canopy have an average diameter (dbh) exceeding 21 in (53 cm). Yes = Category I No = Not a forested wetland for this section Cat. I SC 5.0. Wetlands in Coastal Lagoons Does the wetland meet all of the following criteria of a wetland in a coastal lagoon?  The wetland lies in a depression adjacent to marine waters that is wholly or partially separated from marine waters by sandbanks, gravel banks, shingle, or, less frequently, rocks  The lagoon in which the wetland is located contains ponded water that is saline or brackish (> 0.5 ppt) during most of the year in at least a portion of the lagoon (needs to be measured near the bottom) Yes – Go to SC 5.1 No = Not a wetland in a coastal lagoon SC 5.1. Does the wetland meet all of the following three conditions?  The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing), and has less than 20% cover of aggressive, opportunistic plant species (see list of species on p. 100).  At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un -grazed or un- mowed grassland.  The wetland is larger than 1/10 ac (4350 ft2) Yes = Category I No = Category II Cat. I Cat. II SC 6.0. Interdunal Wetlands Is the wetland west of the 1889 line (also called the Western Boundary of Upland Ownership or WBUO)? If you answer yes you will still need to rate the wetland based on its habitat functions. In practical terms that means the following geographic areas:  Long Beach Peninsula: Lands west of SR 103  Grayland-Westport: Lands west of SR 105  Ocean Shores-Copalis: Lands west of SR 115 and SR 109 Yes – Go to SC 6.1 No = not an interdunal wetland for rating SC 6.1. Is the wetland 1 ac or larger and scores an 8 or 9 for the habitat functions on the form (rates H,H,H or H,H,M for the three aspects of function)? Yes = Category I No – Go to SC 6.2 SC 6.2. Is the wetland 1 ac or larger, or is it in a mosaic of wetlands that is 1 ac or larger? Yes = Category II No – Go to SC 6.3 SC 6.3. Is the unit between 0.1 and 1 ac, or is it in a mosaic of wetlands that is between 0.1 and 1 ac? Yes = Category III No = Category IV Cat I Cat. II Cat. III Cat. IV Category of wetland based on Special Characteristics If you answered No for all types, enter “Not Applicable” on Summary Form A N/A Wetland A Notes: - Entire wetland is scrub-shrub Cowardin class - Entire wetland is saturated - Dense, uncut vegetation is ~ 60% of wetland - Dense ridgid vegetation ~50% of wetland Wetland A Rating Figure 1. Cowardin Class, Hydroperiod and Pollutant Generating Surfaces Pollutant generating surface within 150 foot buffer 100% of 1 km buffer= high intensity land use Wetland A Rating Figure 2. One Kilometer Buffer Land Use Wetland A Rating Figure 3. Section 303(d) Ecology Screen Capture Wetland A Rating Figure 4. WRIA 8 TMDL Screen Capture Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 1 Rating Form – Effective January 1, 2015 Score for each function based on three ratings (order of ratings is not important) 9 = H,H,H 8 = H,H,M 7 = H,H,L 7 = H,M,M 6 = H,M,L 6 = M,M,M 5 = H,L,L 5 = M,M,L 4 = M,L,L 3 = L,L,L RATING SUMMARY – Western Washington Name of wetland (or ID #): _________________________________ Date of site visit: _____ Rated by____________________________ Trained by Ecology?__ Yes ___No Date of training______ HGM Class used for rating_________________ Wetland has multiple HGM classes?___Y ____N NOTE: Form is not complete without the figures requested (figures can be combined). Source of base aerial photo/map ______________________________________ OVERALL WETLAND CATEGORY ____ (based on functions___ or special characteristics___) 1.Category of wetland based on FUNCTIONS _______Category I – Total score = 23 - 27 _______Category II – Total score = 20 - 22 _______Category III – Total score = 16 - 19 _______Category IV – Total score = 9 - 15 FUNCTION Improving Water Quality Hydrologic Habitat Circle the appropriate ratings Site Potential H M L H M L H M L Landscape Potential H M L H M L H M L Value H M L H M L H M L TOTAL Score Based on Ratings 2.Category based on SPECIAL CHARACTERISTICS of wetland CHARACTERISTIC CATEGORY Estuarine I II Wetland of High Conservation Value I Bog I Mature Forest I Old Growth Forest I Coastal Lagoon I II Interdunal I II III IV None of the above A 477 18 X S Corbin, (PWS)X 10/09 and 5/ 14 Depressional Wetland B X Google Earth III X 7/6 and 7/7/15 B Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 2 Rating Form – Effective January 1, 2015 Maps and figures required to answer questions correctly for Western Washington Depressional Wetlands Map of: To answer questions: Figure # Cowardin plant classes D 1.3, H 1.1, H 1.4 Hydroperiods D 1.4, H 1.2 Location of outlet (can be added to map of hydroperiods) D 1.1, D 4.1 Boundary of area within 150 ft of the wetland (can be added to another figure) D 2.2, D 5.2 Map of the contributing basin D 4.3, D 5.3 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) D 3.1, D 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) D 3.3 Riverine Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Ponded depressions R 1.1 Boundary of area within 150 ft of the wetland (can be added to another figure) R 2.4 Plant cover of trees, shrubs, and herbaceous plants R 1.2, R 4.2 Width of unit vs. width of stream (can be added to another figure) R 4.1 Map of the contributing basin R 2.2, R 2.3, R 5.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) R 3.1 Screen capture of list of TMDLs for WRIA in which unit is found (from web) R 3.2, R 3.3 Lake Fringe Wetlands Map of: To answer questions: Figure # Cowardin plant classes L 1.1, L 4.1, H 1.1, H 1.4 Plant cover of trees, shrubs, and herbaceous plants L 1.2 Boundary of area within 150 ft of the wetland (can be added to another figure) L 2.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) L 3.1, L 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) L 3.3 Slope Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Plant cover of dense trees, shrubs, and herbaceous plants S 1.3 Plant cover of dense, rigid trees, shrubs, and herbaceous plants (can be added to figure above) S 4.1 Boundary of 150 ft buffer (can be added to another figure) S 2.1, S 5.1 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) S 3.1, S 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) S 3.3 1 1 B 1 1 1 2 3 4 5 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 3 Rating Form – Effective January 1, 2015 HGM Classification of Wetlands in Western Washington 1.Are the water levels in the entire unit usually controlled by tides except during floods? NO – go to 2 YES – the wetland class is Tidal Fringe – go to 1.1 1.1 Is the salinity of the water during periods of annual low flow below 0.5 ppt (parts per thousand)? NO – Saltwater Tidal Fringe (Estuarine) YES – Freshwater Tidal Fringe If your wetland can be classified as a Freshwater Tidal Fringe use the forms for Riverine wetlands. If it is Saltwater Tidal Fringe it is an Estuarine wetland and is not scored. This method cannot be used to score functions for estuarine wetlands. 2.The entire wetland unit is flat and precipitation is the only source (>90%) of water to it. Groundwater and surface water runoff are NOT sources of water to the unit. NO – go to 3 YES – The wetland class is Flats If your wetland can be classified as a Flats wetland, use the form for Depressional wetlands. 3.Does the entire wetland unit meet all of the following criteria? ___The vegetated part of the wetland is on the shores of a body of permanent open water (without any plants on the surface at any time of the year) at least 20 ac (8 ha) in size; ___At least 30% of the open water area is deeper than 6.6 ft (2 m). NO – go to 4 YES – The wetland class is Lake Fringe (Lacustrine Fringe) 4.Does the entire wetland unit meet all of the following criteria? ____The wetland is on a slope (slope can be very gradual), ____The water flows through the wetland in one direction (unidirectional) and usually comes from seeps. It may flow subsurface, as sheetflow, or in a swale without distinct banks, ____The water leaves the wetland without being impounded. NO – go to 5 YES – The wetland class is Slope NOTE: Surface water does not pond in these type of wetlands except occasionally in very small and shallow depressions or behind hummocks (depressions are usually <3 ft diameter and less than 1 ft deep). 5.Does the entire wetland unit meet all of the following criteria? ____The unit is in a valley, or stream channel, where it gets inundated by overbank flooding from that stream or river, ____The overbank flooding occurs at least once every 2 years. For questions 1-7, the criteria described must apply to the entire unit being rated. If the hydrologic criteria listed in each question do not apply to the entire unit being rated, you probably have a unit with multiple HGM classes. In this case, identify which hydrologic criteria in questions 1-7 apply, and go to Question 8. B Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 4 Rating Form – Effective January 1, 2015 NO – go to 6 YES – The wetland class is Riverine NOTE: The Riverine unit can contain depressions that are filled with water when the river is not flooding 6. Is the entire wetland unit in a topographic depression in which water ponds, or is saturated to the surface, at some time during the year? This means that any outlet, if present, is higher than the interior of the wetland. NO – go to 7 YES – The wetland class is Depressional 7.Is the entire wetland unit located in a very flat area with no obvious depression and no overbank flooding? The unit does not pond surface water more than a few inches. The unit seems to be maintained by high groundwater in the area. The wetland may be ditched, but has no obvious natural outlet. NO – go to 8 YES – The wetland class is Depressional 8.Your wetland unit seems to be difficult to classify and probably contains several different HGM classes. For example, seeps at the base of a slope may grade into a riverine floodplain, or a small stream within a Depressional wetland has a zone of flooding along its sides. GO BACK AND IDENTIFY WHICH OF THE HYDROLOGIC REGIMES DESCRIBED IN QUESTIONS 1-7 APPLY TO DIFFERENT AREAS IN THE UNIT (make a rough sketch to help you decide). Use the following table to identify the appropriate class to use for the rating system if you have several HGM classes present within the wetland unit being scored. NOTE: Use this table only if the class that is recommended in the second column represents 10% or more of the total area of the wetland unit being rated. If the area of the HGM class listed in column 2 is less than 10% of the unit; classify the wetland using the class that represents more than 90% of the total area. HGM classes within the wetland unit being rated HGM class to use in rating Slope + Riverine Riverine Slope + Depressional Depressional Slope + Lake Fringe Lake Fringe Depressional + Riverine along stream within boundary of depression Depressional Depressional + Lake Fringe Depressional Riverine + Lake Fringe Riverine Salt Water Tidal Fringe and any other class of freshwater wetland Treat as ESTUARINE If you are still unable to determine which of the above criteria apply to your wetland, or if you have more than 2 HGM classes within a wetland boundary, classify the wetland as Depressional for the rating. B Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 5 Rating Form – Effective January 1, 2015 DEPRESSIONAL AND FLATS WETLANDS Water Quality Functions - Indicators that the site functions to improve water quality D 1.0. Does the site have the potential to improve water quality? D 1.1. Characteristics of surface water outflows from the wetland: Wetland is a depression or flat depression (QUESTION 7 on key) with no surface water leaving it (no outlet). points = 3 Wetland has an intermittently flowing stream or ditch, OR highly constricted permanently flowing outlet. points = 2 Wetland has an unconstricted, or slightly constricted, surface outlet that is permanently flowing points = 1 Wetland is a flat depression (QUESTION 7 on key), whose outlet is a permanently flowing ditch. points = 1 D 1.2. The soil 2 in below the surface (or duff layer) is true clay or true organic (use NRCS definitions).Yes = 4 No = 0 D 1.3. Characteristics and distribution of persistent plants (Emergent, Scrub-shrub, and/or Forested Cowardin classes): Wetland has persistent, ungrazed, plants > 95% of area points = 5 Wetland has persistent, ungrazed, plants > ½ of area points = 3 Wetland has persistent, ungrazed plants > 1/10 of area points = 1 Wetland has persistent, ungrazed plants <1/10 of area points = 0 D 1.4. Characteristics of seasonal ponding or inundation : This is the area that is ponded for at least 2 months. See description in manual. Area seasonally ponded is > ½ total area of wetland points = 4 Area seasonally ponded is > ¼ total area of wetland points = 2 Area seasonally ponded is < ¼ total area of wetland points = 0 Total for D 1 Add the points in the boxes above Rating of Site Potential If score is: 12-16 = H 6-11 = M 0-5 = L Record the rating on the first page D 2.0. Does the landscape have the potential to support the water quality function of the site? D 2.1. Does the wetland unit receive stormwater discharges? Yes = 1 No = 0 D 2.2. Is > 10% of the area within 150 ft of the wetland in land uses that generate pollutants? Yes = 1 No = 0 D 2.3. Are there septic systems within 250 ft of the wetland? Yes = 1 No = 0 D 2.4. Are there other sources of pollutants coming into the wetland that are not listed in questions D 2.1 -D 2.3? Source_______________ Yes = 1 No = 0 Total for D 2 Add the points in the boxes above Rating of Landscape Potential If score is: 3 or 4 = H 1 or 2 = M 0 = L Record the rating on the first page D 3.0. Is the water quality improvement provided by the site valuable to society? D 3.1. Does the wetland discharge directly (i.e., within 1 mi) to a stream, river, lake, or marine water that is on the 303(d) list? Yes = 1 No = 0 D 3.2. Is the wetland in a basin or sub-basin where an aquatic resource is on the 303(d) list? Yes = 1 No = 0 D 3.3. Has the site been identified in a watershed or local plan as important for maintaining water quality (answer YES if there is a TMDL for the basin in which the unit is found)? Yes = 2 No = 0 Total for D 3 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page B 3 0 1 4 8 X residential, dog poop from dog walkers 1 1 0 1 3 0 1 0 1 X X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 6 Rating Form – Effective January 1, 2015 DEPRESSIONAL AND FLATS WETLANDS Hydrologic Functions - Indicators that the site functions to reduce flooding and stream degradation D 4.0. Does the site have the potential to reduce flooding and erosion? D 4.1. Characteristics of surface water outflows from the wetland: Wetland is a depression or flat depression with no surface water leaving it (no outlet) points = 4 Wetland has an intermittently flowing stream or ditch, OR highly constricted permanently flowing outletpoints = 2 Wetland is a flat depression (QUESTION 7 on key), whose outlet is a permanently flowing ditch points = 1 Wetland has an unconstricted, or slightly constricted, surface outlet that is permanently flowing points = 0 D 4.2. Depth of storage during wet periods: Estimate the height of ponding above the bottom of the outlet. For wetlands with no outlet, measure from the surface of permanent water or if dry, the deepest part. Marks of ponding are 3 ft or more above the surface or bottom of outlet points = 7 Marks of ponding between 2 ft to < 3 ft from surface or bottom of outlet points = 5 Marks are at least 0.5 ft to < 2 ft from surface or bottom of outlet points = 3 The wetland is a “headwater” wetland points = 3 Wetland is flat but has small depressions on the surface that trap water points = 1 Marks of ponding less than 0.5 ft (6 in) points = 0 D 4.3. Contribution of the wetland to storage in the watershed: Estimate the ratio of the area of upstream basin contributing surface water to the wetland to the area of the wetland unit itself. The area of the basin is less than 10 times the area of the unit points = 5 The area of the basin is 10 to 100 times the area of the unit points = 3 The area of the basin is more than 100 times the area of the unit points = 0 Entire wetland is in the Flats class points = 5 Total for D 4 Add the points in the boxes above Rating of Site Potential If score is: 12-16 = H 6-11 = M 0-5 = L Record the rating on the first page D 5.0. Does the landscape have the potential to support hydrologic functions of the site? D 5.1. Does the wetland receive stormwater discharges? Yes = 1 No = 0 D 5.2. Is >10% of the area within 150 ft of the wetland in land uses that generate excess runoff? Yes = 1 No = 0 D 5.3. Is more than 25% of the contributing basin of the wetland covered with intensive human land uses (residential at >1 residence/ac, urban, commercial, agriculture, etc.)? Yes = 1 No = 0 Total for D 5 Add the points in the boxes above Rating of Landscape Potential If score is: 3 = H 1 or 2 = M 0 = L Record the rating on the first page D 6.0. Are the hydrologic functions provided by the site valuable to society? D 6.1. The unit is in a landscape that has flooding problems. Choose the description that best matches conditions around the wetland unit being rated. Do not add points. Choose the highest score if more than one condition is met . The wetland captures surface water that would otherwise flow down -gradient into areas where flooding has damaged human or natural resources (e.g., houses or salmon redds): Flooding occurs in a sub-basin that is immediately down-gradient of unit. points = 2 Surface flooding problems are in a sub-basin farther down-gradient. points = 1 Flooding from groundwater is an issue in the sub-basin. points = 1 The existing or potential outflow from the wetland is so constrained by human or natural conditions that the water stored by the wetland cannot reach areas that flood. Explain why _____________ points = 0 There are no problems with flooding downstream of the wetland. points = 0 D 6.2. Has the site been identified as important for flood storage or flood conveyance in a regional flood control plan? Yes = 2 No = 0 Total for D 6 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page B 4 3 3 10 X 1 1 1 3 X 1 1 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 13 Rating Form – Effective January 1, 2015 These questions apply to wetlands of all HGM classes. HABITAT FUNCTIONS - Indicators that site functions to provide important habitat H 1.0. Does the site have the potential to provide habitat? H 1.1. Structure of plant community: Indicators are Cowardin classes and strata within the Forested class. Check the Cowardin plant classes in the wetland. Up to 10 patches may be combined for each class to meet the threshold of ¼ ac or more than 10% of the unit if it is smaller than 2.5 ac. Add the number of structures checked. ____Aquatic bed 4 structures or more: points = 4 ____Emergent 3 structures: points = 2 ____Scrub-shrub (areas where shrubs have > 30% cover) 2 structures: points = 1 ____Forested (areas where trees have > 30% cover) 1 structure: points = 0 If the unit has a Forested class, check if: ____The Forested class has 3 out of 5 strata (canopy, sub-canopy, shrubs, herbaceous, moss/ground-cover) that each cover 20% within the Forested polygon H 1.2. Hydroperiods Check the types of water regimes (hydroperiods) present within the wetland. The water regime has to cover more than 10% of the wetland or ¼ ac to count (see text for descriptions of hydroperiods). ____Permanently flooded or inundated 4 or more types present: points = 3 ____Seasonally flooded or inundated 3 types present: points = 2 ____Occasionally flooded or inundated 2 types present: points = 1 ____Saturated only 1 type present: points = 0 ____Permanently flowing stream or river in, or adjacent to, the wetland ____Seasonally flowing stream in, or adjacent to, the wetland ____Lake Fringe wetland 2 points ____Freshwater tidal wetland 2 points H 1.3. Richness of plant species Count the number of plant species in the wetland that cover at least 10 ft 2. Different patches of the same species can be combined to meet the size threshold and you do not have to name the species. Do not include Eurasian milfoil, reed canarygrass, purple loosestrife, Canadian thistle If you counted: > 19 species points = 2 5 - 19 species points = 1 < 5 species points = 0 H 1.4. Interspersion of habitats Decide from the diagrams below whether interspersion among Cowardin plants classes (described in H 1.1), or the classes and unvegetated areas (can include open water or mudflats) is high, moderate, low, or none. If you have four or more plant classes or three classes and open water, the rating is always high. None = 0 points Low = 1 point Moderate = 2 points All three diagrams in this row are HIGH = 3points B X 0 X X 1 1 0 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 14 Rating Form – Effective January 1, 2015 H 1.5. Special habitat features: Check the habitat features that are present in the wetland. The number of checks is the number of points. ____Large, downed, woody debris within the wetland (> 4 in diameter and 6 ft long). ____Standing snags (dbh > 4 in) within the wetland ____Undercut banks are present for at least 6.6 ft (2 m) and/or overhanging plants extends at least 3.3 ft (1 m) over a stream (or ditch) in, or contiguous with the wetland, for at least 33 ft (10 m) ____Stable steep banks of fine material that might be used by beaver or muskrat for denning (> 30 degree slope) OR signs of recent beaver activity are present (cut shrubs or trees that have not yet weathered where wood is exposed) ____At least ¼ ac of thin-stemmed persistent plants or woody branches are present in areas that are permanently or seasonally inundated (structures for egg-laying by amphibians) ____Invasive plants cover less than 25% of the wetland area in every stratum of plants (see H 1.1 for list of strata) Total for H 1 Add the points in the boxes above Rating of Site Potential If score is: 15-18 = H 7-14 = M 0-6 = L Record the rating on the first page H 2.0. Does the landscape have the potential to support the habitat functions of the site? H 2.1. Accessible habitat (include only habitat that directly abuts wetland unit). Calculate: % undisturbed habitat + [(% moderate and low intensity land uses)/2] = _______% If total accessible habitat is: > 1/3 (33.3%) of 1 km Polygon points = 3 20-33% of 1 km Polygon points = 2 10-19% of 1 km Polygon points = 1 < 10% of 1 km Polygon points = 0 H 2.2. Undisturbed habitat in 1 km Polygon around the wetland. Calculate: % undisturbed habitat + [(% moderate and low intensity land uses)/2] = _______% Undisturbed habitat > 50% of Polygon points = 3 Undisturbed habitat 10-50% and in 1-3 patches points = 2 Undisturbed habitat 10-50% and > 3 patches points = 1 Undisturbed habitat < 10% of 1 km Polygon points = 0 H 2.3. Land use intensity in 1 km Polygon: If > 50% of 1 km Polygon is high intensity land use points = (- 2) ≤ 50% of 1 km Polygon is high intensity points = 0 Total for H 2 Add the points in the boxes above Rating of Landscape Potential If score is: 4-6 = H 1-3 = M < 1 = L Record the rating on the first page H 3.0. Is the habitat provided by the site valuable to society? H 3.1. Does the site provide habitat for species valued in laws, regulations, or policies? Choose only the highest score that applies to the wetland being rated. Site meets ANY of the following criteria: points = 2  It has 3 or more priority habitats within 100 m (see next page)  It provides habitat for Threatened or Endangered species (any plant or animal on the state or federal lists)  It is mapped as a location for an individual WDFW priority species  It is a Wetland of High Conservation Value as determined by the Department of Natural Resources  It has been categorized as an important habitat site in a local or regional comprehensive plan, in a Shoreline Master Plan, or in a watershed plan Site has 1 or 2 priority habitats (listed on next page) within 100 m points = 1 Site does not meet any of the criteria above points = 0 Rating of Value If score is: 2 = H 1 = M 0 = L Record the rating on the first page B X X X 3 5 X 0 0 0 0 0 0 0 0 -2 -2 X 1 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 15 Rating Form – Effective January 1, 2015 WDFW Priority Habitats Priority habitats listed by WDFW (see complete descriptions of WDFW priority habitats, and the counties in which they can be found, in: Washington Department of Fish and Wildlife. 2008. Priority Habitat and Species List. Olympia, Washington. 177 pp. http://wdfw.wa.gov/publications/00165/wdfw00165.pdf or access the list from here: http://wdfw.wa.gov/conservation/phs/list/) Count how many of the following priority habitats are within 330 ft (100 m) of the wetland unit: NOTE: This question is independent of the land use between the wetland unit and the priority habitat.  Aspen Stands: Pure or mixed stands of aspen greater than 1 ac (0.4 ha).  Biodiversity Areas and Corridors: Areas of habitat that are relatively important to various species of native fish and wildlife (full descriptions in WDFW PHS report).  Herbaceous Balds: Variable size patches of grass and forbs on shallow soils over bedrock.  Old-growth/Mature forests: Old-growth west of Cascade crest – Stands of at least 2 tree species, forming a multi- layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha ) > 32 in (81 cm) dbh or > 200 years of age. Mature forests – Stands with average diameters exceeding 21 in (53 cm) dbh; crown cover may be less than 100%; decay, decadence, numbers of snags, and quantity of large downed material is generally less than that found in old-growth; 80-200 years old west of the Cascade crest.  Oregon White Oak: Woodland stands of pure oak or oak/conifer associations where canopy coverage of the oak component is important (full descriptions in WDFW PHS report p. 158 – see web link above).  Riparian: The area adjacent to aquatic systems with flowing water that contains elements of both aquatic and terrestrial ecosystems which mutually influence each other.  Westside Prairies: Herbaceous, non-forested plant communities that can either take the form of a dry prairie or a wet prairie (full descriptions in WDFW PHS report p. 161 – see web link above).  Instream: The combination of physical, biological, and chemical processes and conditions that interact to provide functional life history requirements for instream fish and wildlife resources.  Nearshore: Relatively undisturbed nearshore habitats. These include Coastal Nearshore, Open Coast Nearshore, and Puget Sound Nearshore. (full descriptions of habitats and the definition of relatively undisturbed are in WDFW report – see web link on previous page).  Caves: A naturally occurring cavity, recess, void, or system of interconnected passages under the earth in soils, rock, ice, or other geological formations and is large enough to contain a human.  Cliffs: Greater than 25 ft (7.6 m) high and occurring below 5000 ft elevation.  Talus: Homogenous areas of rock rubble ranging in average size 0.5 - 6.5 ft (0.15 - 2.0 m), composed of basalt, andesite, and/or sedimentary rock, including riprap slides and mine tailings. May be associated with cliffs.  Snags and Logs: Trees are considered snags if they are dead or dying and exhibit sufficient decay characteristics to enable cavity excavation/use by wildlife. Priority snags have a diameter at breast height of > 20 in (51 cm) in western Washington and are > 6.5 ft (2 m) in height. Priority logs are > 12 in (30 cm) in diameter at the largest end, and > 20 ft (6 m) long. Note: All vegetated wetlands are by definition a priority habitat but are not included in this list because they are addressed elsewhere. X B Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 16 Rating Form – Effective January 1, 2015 CATEGORIZATION BASED ON SPECIAL CHARACTERISTICS Wetland Type Check off any criteria that apply to the wetland. Circle the category when the appropriate criteria are met. Category SC 1.0. Estuarine wetlands Does the wetland meet the following criteria for Estuarine wetlands?  The dominant water regime is tidal,  Vegetated, and  With a salinity greater than 0.5 ppt Yes –Go to SC 1.1 No= Not an estuarine wetland SC 1.1. Is the wetland within a National Wildlife Refuge, National Park, National Estuary Reserve, Natural Area Preserve, State Park or Educational, Environmental, or Scientific Reserve designated under WAC 332 -30-151? Yes = Category I No - Go to SC 1.2 Cat. I SC 1.2. Is the wetland unit at least 1 ac in size and meets at least two of the following three conditions?  The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing, and has less than 10% cover of non-native plant species. (If non-native species are Spartina, see page 25)  At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-grazed or un- mowed grassland.  The wetland has at least two of the following features: tidal channels, depressions with open water, or contiguous freshwater wetlands. Yes = Category I No = Category II Cat. I Cat. II SC 2.0. Wetlands of High Conservation Value (WHCV) SC 2.1. Has the WA Department of Natural Resources updated their website to include the list of Wetlands of High Conservation Value? Yes – Go to SC 2.2 No – Go to SC 2.3 SC 2.2. Is the wetland listed on the WDNR database as a Wetland of High Conservation Value? Yes = Category I No = Not a WHCV SC 2.3. Is the wetland in a Section/Township/Range that contains a Natural Heritage wetland? http://www1.dnr.wa.gov/nhp/refdesk/datasearch/wnhpwetlands.pdf Yes – Contact WNHP/WDNR and go to SC 2.4 No = Not a WHCV SC 2.4. Has WDNR identified the wetland within the S/T/R as a Wetland of High Conservation Value and listed it on their website? Yes = Category I No = Not a WHCV Cat. I SC 3.0. Bogs Does the wetland (or any part of the unit) meet both the criteria for soils and vegetation in bogs? Use the key below. If you answer YES you will still need to rate the wetland based on its functions. SC 3.1. Does an area within the wetland unit have organic soil horizons, either peats or mucks, that compose 16 in or more of the first 32 in of the soil profile? Yes – Go to SC 3.3 No – Go to SC 3.2 SC 3.2. Does an area within the wetland unit have organic soils, either peats or mucks, that are less than 16 in deep over bedrock, or an impermeable hardpan such as clay or volcanic ash, or that are floating on top of a lake or pond? Yes – Go to SC 3.3 No = Is not a bog SC 3.3. Does an area with peats or mucks have more than 70% cover of mosses at ground level, AND at least a 30% cover of plant species listed in Table 4? Yes = Is a Category I bog No – Go to SC 3.4 NOTE: If you are uncertain about the extent of mosses in the understory , you may substitute that criterion by measuring the pH of the water that seeps into a hole dug at least 16 in deep. If the pH is less than 5.0 and the plant species in Table 4 are present, the wetland is a bog. SC 3.4. Is an area with peats or mucks forested (> 30% cover) with Sitka spruce, subalpine fir, western red cedar, western hemlock, lodgepole pine, quaking aspen, Engelmann spruce, or western white pine, AND any of the species (or combination of species) listed in Table 4 provide more than 30% of the cover under the canopy? Yes = Is a Category I bog No = Is not a bog Cat. I B Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 17 Rating Form – Effective January 1, 2015 SC 4.0. Forested Wetlands Does the wetland have at least 1 contiguous acre of forest that meets one of these criteria for the WA Department of Fish and Wildlife’s forests as priority habitats? If you answer YES you will still need to rate the wetland based on its functions.  Old-growth forests (west of Cascade crest): Stands of at least two tree species, forming a multi-layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha) that are at least 200 years of age OR have a diameter at breast height (dbh) of 32 in (81 cm) or more.  Mature forests (west of the Cascade Crest): Stands where the largest trees are 80- 200 years old OR the species that make up the canopy have an average diameter (dbh) exceeding 21 in (53 cm). Yes = Category I No = Not a forested wetland for this section Cat. I SC 5.0. Wetlands in Coastal Lagoons Does the wetland meet all of the following criteria of a wetland in a coastal lagoon?  The wetland lies in a depression adjacent to marine waters that is wholly or partially separated from marine waters by sandbanks, gravel banks, shingle, or, less frequently, rocks  The lagoon in which the wetland is located contains ponded water that is saline or brackish (> 0.5 ppt) during most of the year in at least a portion of the lagoon (needs to be measured near the bottom) Yes – Go to SC 5.1 No = Not a wetland in a coastal lagoon SC 5.1. Does the wetland meet all of the following three conditions?  The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing), and has less than 20% cover of aggressive, opportunistic plant species (see list of species on p. 100).  At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un -grazed or un- mowed grassland.  The wetland is larger than 1/10 ac (4350 ft2) Yes = Category I No = Category II Cat. I Cat. II SC 6.0. Interdunal Wetlands Is the wetland west of the 1889 line (also called the Western Boundary of Upland Ownership or WBUO)? If you answer yes you will still need to rate the wetland based on its habitat functions. In practical terms that means the following geographic areas:  Long Beach Peninsula: Lands west of SR 103  Grayland-Westport: Lands west of SR 105  Ocean Shores-Copalis: Lands west of SR 115 and SR 109 Yes – Go to SC 6.1 No = not an interdunal wetland for rating SC 6.1. Is the wetland 1 ac or larger and scores an 8 or 9 for the habitat functions on the form (rates H,H,H or H,H,M for the three aspects of function)? Yes = Category I No – Go to SC 6.2 SC 6.2. Is the wetland 1 ac or larger, or is it in a mosaic of wetlands that is 1 ac or larger? Yes = Category II No – Go to SC 6.3 SC 6.3. Is the unit between 0.1 and 1 ac, or is it in a mosaic of wetlands that is between 0.1 and 1 ac? Yes = Category III No = Category IV Cat I Cat. II Cat. III Cat. IV Category of wetland based on Special Characteristics If you answered No for all types, enter “Not Applicable” on Summary Form B N/A Wetland B Rating Figure 1. Cowardin Class, Hydroperiod, and Pollutant Generating Surface Pollutant Generating Surface in 150 foot buffer Wetland B Notes: - No outlet present - Entire wetland is forested Cowardin classs Area inside blue polygon = seasonally inundated Area outside blue polygon = saturated Wetland B Rating Figure 2. Contributing Basin Wetland B Contributing Basin Wetland B Rating Figure 3. 1 Kilometer Buffer 100% High Intensity Land Use Wetland B Rating Figure 4. 303d Screen Shot Wetland B Rating Figure 5. WRIA 8 TMDL Screen Shot Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 1 Rating Form – Effective January 1, 2015 Score for each function based on three ratings (order of ratings is not important) 9 = H,H,H 8 = H,H,M 7 = H,H,L 7 = H,M,M 6 = H,M,L 6 = M,M,M 5 = H,L,L 5 = M,M,L 4 = M,L,L 3 = L,L,L RATING SUMMARY – Western Washington Name of wetland (or ID #): _________________________________ Date of site visit: _____ Rated by____________________________ Trained by Ecology?__ Yes ___No Date of training______ HGM Class used for rating_________________ Wetland has multiple HGM classes?___Y ____N NOTE: Form is not complete without the figures requested (figures can be combined). Source of base aerial photo/map ______________________________________ OVERALL WETLAND CATEGORY ____ (based on functions___ or special characteristics___) 1.Category of wetland based on FUNCTIONS _______Category I – Total score = 23 - 27 _______Category II – Total score = 20 - 22 _______Category III – Total score = 16 - 19 _______Category IV – Total score = 9 - 15 FUNCTION Improving Water Quality Hydrologic Habitat Circle the appropriate ratings Site Potential H M L H M L H M L Landscape Potential H M L H M L H M L Value H M L H M L H M L TOTAL Score Based on Ratings 2.Category based on SPECIAL CHARACTERISTICS of wetland CHARACTERISTIC CATEGORY Estuarine I II Wetland of High Conservation Value I Bog I Mature Forest I Old Growth Forest I Coastal Lagoon I II Interdunal I II III IV None of the above C Wetland C S. Corbin (PWS)X 10/09 and 5/14 Slope X Google Earth 7/6 and 7/7/15 6 4 4 14 X IV X 5 13 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 2 Rating Form – Effective January 1, 2015 Maps and figures required to answer questions correctly for Western Washington Depressional Wetlands Map of: To answer questions: Figure # Cowardin plant classes D 1.3, H 1.1, H 1.4 Hydroperiods D 1.4, H 1.2 Location of outlet (can be added to map of hydroperiods) D 1.1, D 4.1 Boundary of area within 150 ft of the wetland (can be added to another figure) D 2.2, D 5.2 Map of the contributing basin D 4.3, D 5.3 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) D 3.1, D 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) D 3.3 Riverine Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Ponded depressions R 1.1 Boundary of area within 150 ft of the wetland (can be added to another figure) R 2.4 Plant cover of trees, shrubs, and herbaceous plants R 1.2, R 4.2 Width of unit vs. width of stream (can be added to another figure) R 4.1 Map of the contributing basin R 2.2, R 2.3, R 5.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) R 3.1 Screen capture of list of TMDLs for WRIA in which unit is found (from web) R 3.2, R 3.3 Lake Fringe Wetlands Map of: To answer questions: Figure # Cowardin plant classes L 1.1, L 4.1, H 1.1, H 1.4 Plant cover of trees, shrubs, and herbaceous plants L 1.2 Boundary of area within 150 ft of the wetland (can be added to another figure) L 2.2 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) L 3.1, L 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) L 3.3 Slope Wetlands Map of: To answer questions: Figure # Cowardin plant classes H 1.1, H 1.4 Hydroperiods H 1.2 Plant cover of dense trees, shrubs, and herbaceous plants S 1.3 Plant cover of dense, rigid trees, shrubs, and herbaceous plants (can be added to figure above) S 4.1 Boundary of 150 ft buffer (can be added to another figure) S 2.1, S 5.1 1 km Polygon: Area that extends 1 km from entire wetland edge - including polygons for accessible habitat and undisturbed habitat H 2.1, H 2.2, H 2.3 Screen capture of map of 303(d) listed waters in basin (from Ecology website) S 3.1, S 3.2 Screen capture of list of TMDLs for WRIA in which unit is found (from web) S 3.3 C 11 1 1 1 2 3 4 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 3 Rating Form – Effective January 1, 2015 HGM Classification of Wetlands in Western Washington 1.Are the water levels in the entire unit usually controlled by tides except during floods? NO – go to 2 YES – the wetland class is Tidal Fringe – go to 1.1 1.1 Is the salinity of the water during periods of annual low flow below 0.5 ppt (parts per thousand)? NO – Saltwater Tidal Fringe (Estuarine) YES – Freshwater Tidal Fringe If your wetland can be classified as a Freshwater Tidal Fringe use the forms for Riverine wetlands. If it is Saltwater Tidal Fringe it is an Estuarine wetland and is not scored. This method cannot be used to score functions for estuarine wetlands. 2.The entire wetland unit is flat and precipitation is the only source (>90%) of water to it. Groundwater and surface water runoff are NOT sources of water to the unit. NO – go to 3 YES – The wetland class is Flats If your wetland can be classified as a Flats wetland, use the form for Depressional wetlands. 3.Does the entire wetland unit meet all of the following criteria? ___The vegetated part of the wetland is on the shores of a body of permanent open water (without any plants on the surface at any time of the year) at least 20 ac (8 ha) in size; ___At least 30% of the open water area is deeper than 6.6 ft (2 m). NO – go to 4 YES – The wetland class is Lake Fringe (Lacustrine Fringe) 4.Does the entire wetland unit meet all of the following criteria? ____The wetland is on a slope (slope can be very gradual), ____The water flows through the wetland in one direction (unidirectional) and usually comes from seeps. It may flow subsurface, as sheetflow, or in a swale without distinct banks, ____The water leaves the wetland without being impounded. NO – go to 5 YES – The wetland class is Slope NOTE: Surface water does not pond in these type of wetlands except occasionally in very small and shallow depressions or behind hummocks (depressions are usually <3 ft diameter and less than 1 ft deep). 5.Does the entire wetland unit meet all of the following criteria? ____The unit is in a valley, or stream channel, where it gets inundated by overbank flooding from that stream or river, ____The overbank flooding occurs at least once every 2 years. For questions 1-7, the criteria described must apply to the entire unit being rated. If the hydrologic criteria listed in each question do not apply to the entire unit being rated, you probably have a unit with multiple HGM classes. In this case, identify which hydrologic criteria in questions 1-7 apply, and go to Question 8. C Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 4 Rating Form – Effective January 1, 2015 NO – go to 6 YES – The wetland class is Riverine NOTE: The Riverine unit can contain depressions that are filled with water when the river is not flooding 6. Is the entire wetland unit in a topographic depression in which water ponds, or is saturated to the surface, at some time during the year? This means that any outlet, if present, is higher than the interior of the wetland. NO – go to 7 YES – The wetland class is Depressional 7.Is the entire wetland unit located in a very flat area with no obvious depression and no overbank flooding? The unit does not pond surface water more than a few inches. The unit seems to be maintained by high groundwater in the area. The wetland may be ditched, but has no obvious natural outlet. NO – go to 8 YES – The wetland class is Depressional 8.Your wetland unit seems to be difficult to classify and probably contains several different HGM classes. For example, seeps at the base of a slope may grade into a riverine floodplain, or a small stream within a Depressional wetland has a zone of flooding along its sides. GO BACK AND IDENTIFY WHICH OF THE HYDROLOGIC REGIMES DESCRIBED IN QUESTIONS 1-7 APPLY TO DIFFERENT AREAS IN THE UNIT (make a rough sketch to help you decide). Use the following table to identify the appropriate class to use for the rating system if you have several HGM classes present within the wetland unit being scored. NOTE: Use this table only if the class that is recommended in the second column represents 10% or more of the total area of the wetland unit being rated. If the area of the HGM class listed in column 2 is less than 10% of the unit; classify the wetland using the class that represents more than 90% of the total area. HGM classes within the wetland unit being rated HGM class to use in rating Slope + Riverine Riverine Slope + Depressional Depressional Slope + Lake Fringe Lake Fringe Depressional + Riverine along stream within boundary of depression Depressional Depressional + Lake Fringe Depressional Riverine + Lake Fringe Riverine Salt Water Tidal Fringe and any other class of freshwater wetland Treat as ESTUARINE If you are still unable to determine which of the above criteria apply to your wetland, or if you have more than 2 HGM classes within a wetland boundary, classify the wetland as Depressional for the rating. C Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 11 Rating Form – Effective January 1, 2015 SLOPE WETLANDS Water Quality Functions - Indicators that the site functions to improve water quality S 1.0. Does the site have the potential to improve water quality? S 1.1. Characteristics of the average slope of the wetland: (a 1% slope has a 1 ft vertical drop in elevation for every 100 ft of horizontal distance) Slope is 1% or less points = 3 Slope is > 1%-2% points = 2 Slope is > 2%-5% points = 1 Slope is greater than 5% points = 0 S 1.2. The soil 2 in below the surface (or duff layer) is true clay or true organic (use NRCS definitions): Yes = 3 No = 0 S 1.3. Characteristics of the plants in the wetland that trap sediments and pollutants: Choose the points appropriate for the description that best fits the plants in the wetland. Dense means you have trouble seeing the soil surface (>75% cover), and uncut means not grazed or mowed and plants are higher than 6 in. Dense, uncut, herbaceous plants > 90% of the wetland area points = 6 Dense, uncut, herbaceous plants > ½ of area points = 3 Dense, woody, plants > ½ of area points = 2 Dense, uncut, herbaceous plants > ¼ of area points = 1 Does not meet any of the criteria above for plants points = 0 Total for S 1 Add the points in the boxes above Rating of Site Potential If score is: 12 = H 6-11 = M 0-5 = L Record the rating on the first page S 2.0. Does the landscape have the potential to support the water quality function of the site? S 2.1. Is > 10% of the area within 150 ft on the uphill side of the wetland in land uses that generate pollutants? Yes = 1 No = 0 S 2.2. Are there other sources of pollutants coming into the wetland that are not listed in question S 2.1? Other sources ________________ Yes = 1 No = 0 Total for S 2 Add the points in the boxes above Rating of Landscape Potential If score is: 1-2 = M 0 = L Record the rating on the first page S 3.0. Is the water quality improvement provided by the site valuable to society? S 3.1. Does the wetland discharge directly (i.e., within 1 mi) to a stream, river, lake, or marine water that is on the 303(d) list? Yes = 1 No = 0 S 3.2. Is the wetland in a basin or sub-basin where water quality is an issue? At least one aquatic resource in the basin is on the 303(d) list. Yes = 1 No = 0 S 3.3. Has the site been identified in a watershed or local plan as important for maintaining water quality? Answer YES if there is a TMDL for the basin in which unit is found. Yes = 2 No = 0 Total for S 3 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page C 0 0 0 0 X 0 1Dog walkers/ dog poop 1 0 1 2 3 X X X 0 1 Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 12 Rating Form – Effective January 1, 2015 SLOPE WETLANDS Hydrologic Functions - Indicators that the site functions to reduce flooding and stream erosion S 4.0. Does the site have the potential to reduce flooding and stream erosion? S 4.1. Characteristics of plants that reduce the velocity of surface flows during storms: Choose the points appropriate for the description that best fits conditions in the wetland. Stems of plants should be thick enough (usually > 1/8 in), or dense enough, to remain erect during surface flows . Dense, uncut, rigid plants cover > 90% of the area of the wetland points = 1 All other conditions points = 0 Rating of Site Potential If score is: 1 = M 0 = L Record the rating on the first page S 5.0. Does the landscape have the potential to support the hydrologic functions of the site? S 5.1. Is more than 25% of the area within 150 ft upslope of wetland in land uses or cover that generate excess surface runoff? Yes = 1 No = 0 Rating of Landscape Potential If score is: 1 = M 0 = L Record the rating on the first page S 6.0. Are the hydrologic functions provided by the site valuable to society? S 6.1. Distance to the nearest areas downstr eam that have flooding problems: The sub-basin immediately down-gradient of site has flooding problems that result in damage to human or natural resources (e.g., houses or salmon redds) points = 2 Surface flooding problems are in a sub-basin farther down-gradient points = 1 No flooding problems anywhere downstream points = 0 S 6.2. Has the site been identified as important for flood storage or flood conveyance in a regional flood control plan? Yes = 2 No = 0 Total for S 6 Add the points in the boxes above Rating of Value If score is: 2-4 = H 1 = M 0 = L Record the rating on the first page NOTES and FIELD OBSERVATIONS: C 0 X 0 X 1 0 1 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 13 Rating Form – Effective January 1, 2015 These questions apply to wetlands of all HGM classes. HABITAT FUNCTIONS - Indicators that site functions to provide important habitat H 1.0. Does the site have the potential to provide habitat? H 1.1. Structure of plant community: Indicators are Cowardin classes and strata within the Forested class. Check the Cowardin plant classes in the wetland. Up to 10 patches may be combined for each class to meet the threshold of ¼ ac or more than 10% of the unit if it is smaller than 2.5 ac. Add the number of structures checked. ____Aquatic bed 4 structures or more: points = 4 ____Emergent 3 structures: points = 2 ____Scrub-shrub (areas where shrubs have > 30% cover) 2 structures: points = 1 ____Forested (areas where trees have > 30% cover) 1 structure: points = 0 If the unit has a Forested class, check if: ____The Forested class has 3 out of 5 strata (canopy, sub-canopy, shrubs, herbaceous, moss/ground-cover) that each cover 20% within the Forested polygon H 1.2. Hydroperiods Check the types of water regimes (hydroperiods) present within the wetland. The water regime has to cover more than 10% of the wetland or ¼ ac to count (see text for descriptions of hydroperiods). ____Permanently flooded or inundated 4 or more types present: points = 3 ____Seasonally flooded or inundated 3 types present: points = 2 ____Occasionally flooded or inundated 2 types present: points = 1 ____Saturated only 1 type present: points = 0 ____Permanently flowing stream or river in, or adjacent to, the wetland ____Seasonally flowing stream in, or adjacent to, the wetland ____Lake Fringe wetland 2 points ____Freshwater tidal wetland 2 points H 1.3. Richness of plant species Count the number of plant species in the wetland that cover at least 10 ft 2. Different patches of the same species can be combined to meet the size threshold and you do not have to name the species. Do not include Eurasian milfoil, reed canarygrass, purple loosestrife, Canadian thistle If you counted: > 19 species points = 2 5 - 19 species points = 1 < 5 species points = 0 H 1.4. Interspersion of habitats Decide from the diagrams below whether interspersion among Cowardin plants classes (described in H 1.1), or the classes and unvegetated areas (can include open water or mudflats) is high, moderate, low, or none. If you have four or more plant classes or three classes and open water, the rating is always high. None = 0 points Low = 1 point Moderate = 2 points All three diagrams in this row are HIGH = 3points C X 0 X 0 1 0 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 14 Rating Form – Effective January 1, 2015 H 1.5. Special habitat features: Check the habitat features that are present in the wetland. The number of checks is the number of points. ____Large, downed, woody debris within the wetland (> 4 in diameter and 6 ft long). ____Standing snags (dbh > 4 in) within the wetland ____Undercut banks are present for at least 6.6 ft (2 m) and/or overhanging plants extends at least 3.3 ft (1 m) over a stream (or ditch) in, or contiguous with the wetland, for at least 33 ft (10 m) ____Stable steep banks of fine material that might be used by beaver or muskrat for denning (> 30 degree slope) OR signs of recent beaver activity are present (cut shrubs or trees that have not yet weathered where wood is exposed) ____At least ¼ ac of thin-stemmed persistent plants or woody branches are present in areas that are permanently or seasonally inundated (structures for egg-laying by amphibians) ____Invasive plants cover less than 25% of the wetland area in every stratum of plants (see H 1.1 for list of strata) Total for H 1 Add the points in the boxes above Rating of Site Potential If score is: 15-18 = H 7-14 = M 0-6 = L Record the rating on the first page H 2.0. Does the landscape have the potential to support the habitat functions of the site? H 2.1. Accessible habitat (include only habitat that directly abuts wetland unit). Calculate: % undisturbed habitat + [(% moderate and low intensity land uses)/2] = _______% If total accessible habitat is: > 1/3 (33.3%) of 1 km Polygon points = 3 20-33% of 1 km Polygon points = 2 10-19% of 1 km Polygon points = 1 < 10% of 1 km Polygon points = 0 H 2.2. Undisturbed habitat in 1 km Polygon around the wetland. Calculate: % undisturbed habitat + [(% moderate and low intensity land uses)/2] = _______% Undisturbed habitat > 50% of Polygon points = 3 Undisturbed habitat 10-50% and in 1-3 patches points = 2 Undisturbed habitat 10-50% and > 3 patches points = 1 Undisturbed habitat < 10% of 1 km Polygon points = 0 H 2.3. Land use intensity in 1 km Polygon: If > 50% of 1 km Polygon is high intensity land use points = (- 2) ≤ 50% of 1 km Polygon is high intensity points = 0 Total for H 2 Add the points in the boxes above Rating of Landscape Potential If score is: 4-6 = H 1-3 = M < 1 = L Record the rating on the first page H 3.0. Is the habitat provided by the site valuable to society? H 3.1. Does the site provide habitat for species valued in laws, regulations, or policies? Choose only the highest score that applies to the wetland being rated. Site meets ANY of the following criteria: points = 2  It has 3 or more priority habitats within 100 m (see next page)  It provides habitat for Threatened or Endangered species (any plant or animal on the state or federal lists)  It is mapped as a location for an individual WDFW priority species  It is a Wetland of High Conservation Value as determined by the Department of Natural Resources  It has been categorized as an important habitat site in a local or regional comprehensive plan, in a Shoreline Master Plan, or in a watershed plan Site has 1 or 2 priority habitats (listed on next page) within 100 m points = 1 Site does not meet any of the criteria above points = 0 Rating of Value If score is: 2 = H 1 = M 0 = L Record the rating on the first page C X 1 2 X 0 0 0 0 0 0 0 0 -2 -2 X 1 X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 15 Rating Form – Effective January 1, 2015 WDFW Priority Habitats Priority habitats listed by WDFW (see complete descriptions of WDFW priority habitats, and the counties in which they can be found, in: Washington Department of Fish and Wildlife. 2008. Priority Habitat and Species List. Olympia, Washington. 177 pp. http://wdfw.wa.gov/publications/00165/wdfw00165.pdf or access the list from here: http://wdfw.wa.gov/conservation/phs/list/) Count how many of the following priority habitats are within 330 ft (100 m) of the wetland unit: NOTE: This question is independent of the land use between the wetland unit and the priority habitat.  Aspen Stands: Pure or mixed stands of aspen greater than 1 ac (0.4 ha).  Biodiversity Areas and Corridors: Areas of habitat that are relatively important to various species of native fish and wildlife (full descriptions in WDFW PHS report).  Herbaceous Balds: Variable size patches of grass and forbs on shallow soils over bedrock.  Old-growth/Mature forests: Old-growth west of Cascade crest – Stands of at least 2 tree species, forming a multi- layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha ) > 32 in (81 cm) dbh or > 200 years of age. Mature forests – Stands with average diameters exceeding 21 in (53 cm) dbh; crown cover may be less than 100%; decay, decadence, numbers of snags, and quantity of large downed material is generally less than that found in old-growth; 80-200 years old west of the Cascade crest.  Oregon White Oak: Woodland stands of pure oak or oak/conifer associations where canopy coverage of the oak component is important (full descriptions in WDFW PHS report p. 158 – see web link above).  Riparian: The area adjacent to aquatic systems with flowing water that contains elements of both aquatic and terrestrial ecosystems which mutually influence each other.  Westside Prairies: Herbaceous, non-forested plant communities that can either take the form of a dry prairie or a wet prairie (full descriptions in WDFW PHS report p. 161 – see web link above).  Instream: The combination of physical, biological, and chemical processes and conditions that interact to provide functional life history requirements for instream fish and wildlife resources.  Nearshore: Relatively undisturbed nearshore habitats. These include Coastal Nearshore, Open Coast Nearshore, and Puget Sound Nearshore. (full descriptions of habitats and the definition of relatively undisturbed are in WDFW report – see web link on previous page).  Caves: A naturally occurring cavity, recess, void, or system of interconnected passages under the earth in soils, rock, ice, or other geological formations and is large enough to contain a human.  Cliffs: Greater than 25 ft (7.6 m) high and occurring below 5000 ft elevation.  Talus: Homogenous areas of rock rubble ranging in average size 0.5 - 6.5 ft (0.15 - 2.0 m), composed of basalt, andesite, and/or sedimentary rock, including riprap slides and mine tailings. May be associated with cliffs.  Snags and Logs: Trees are considered snags if they are dead or dying and exhibit sufficient decay characteristics to enable cavity excavation/use by wildlife. Priority snags have a diameter at breast height of > 20 in (51 cm) in western Washington and are > 6.5 ft (2 m) in height. Priority logs are > 12 in (30 cm) in diameter at the largest end, and > 20 ft (6 m) long. Note: All vegetated wetlands are by definition a priority habitat but are not included in this list because they are addressed elsewhere. C X Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 16 Rating Form – Effective January 1, 2015 CATEGORIZATION BASED ON SPECIAL CHARACTERISTICS Wetland Type Check off any criteria that apply to the wetland. Circle the category when the appropriate criteria are met. Category SC 1.0. Estuarine wetlands Does the wetland meet the following criteria for Estuarine wetlands?  The dominant water regime is tidal,  Vegetated, and  With a salinity greater than 0.5 ppt Yes –Go to SC 1.1 No= Not an estuarine wetland SC 1.1. Is the wetland within a National Wildlife Refuge, National Park, National Estuary Reserve, Natural Area Preserve, State Park or Educational, Environmental, or Scientific Reserve designated under WAC 332 -30-151? Yes = Category I No - Go to SC 1.2 Cat. I SC 1.2. Is the wetland unit at least 1 ac in size and meets at least two of the following three conditions?  The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing, and has less than 10% cover of non-native plant species. (If non-native species are Spartina, see page 25)  At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un-grazed or un- mowed grassland.  The wetland has at least two of the following features: tidal channels, depressions with open water, or contiguous freshwater wetlands. Yes = Category I No = Category II Cat. I Cat. II SC 2.0. Wetlands of High Conservation Value (WHCV) SC 2.1. Has the WA Department of Natural Resources updated their website to include the list of Wetlands of High Conservation Value? Yes – Go to SC 2.2 No – Go to SC 2.3 SC 2.2. Is the wetland listed on the WDNR database as a Wetland of High Conservation Value? Yes = Category I No = Not a WHCV SC 2.3. Is the wetland in a Section/Township/Range that contains a Natural Heritage wetland? http://www1.dnr.wa.gov/nhp/refdesk/datasearch/wnhpwetlands.pdf Yes – Contact WNHP/WDNR and go to SC 2.4 No = Not a WHCV SC 2.4. Has WDNR identified the wetland within the S/T/R as a Wetland of High Conservation Value and listed it on their website? Yes = Category I No = Not a WHCV Cat. I SC 3.0. Bogs Does the wetland (or any part of the unit) meet both the criteria for soils and vegetation in bogs? Use the key below. If you answer YES you will still need to rate the wetland based on its functions. SC 3.1. Does an area within the wetland unit have organic soil horizons, either peats or mucks, that compose 16 in or more of the first 32 in of the soil profile? Yes – Go to SC 3.3 No – Go to SC 3.2 SC 3.2. Does an area within the wetland unit have organic soils, either peats or mucks, that are less than 16 in deep over bedrock, or an impermeable hardpan such as clay or volcanic ash, or that are floating on top of a lake or pond? Yes – Go to SC 3.3 No = Is not a bog SC 3.3. Does an area with peats or mucks have more than 70% cover of mosses at ground level, AND at least a 30% cover of plant species listed in Table 4? Yes = Is a Category I bog No – Go to SC 3.4 NOTE: If you are uncertain about the extent of mosses in the understory , you may substitute that criterion by measuring the pH of the water that seeps into a hole dug at least 16 in deep. If the pH is less than 5.0 and the plant species in Table 4 are present, the wetland is a bog. SC 3.4. Is an area with peats or mucks forested (> 30% cover) with Sitka spruce, subalpine fir, western red cedar, western hemlock, lodgepole pine, quaking aspen, Engelmann spruce, or western white pine, AND any of the species (or combination of species) listed in Table 4 provide more than 30% of the cover under the canopy? Yes = Is a Category I bog No = Is not a bog Cat. I C Wetland name or number ______ Wetland Rating System for Western WA: 2014 Update 17 Rating Form – Effective January 1, 2015 SC 4.0. Forested Wetlands Does the wetland have at least 1 contiguous acre of forest that meets one of these criteria for the WA Department of Fish and Wildlife’s forests as priority habitats? If you answer YES you will still need to rate the wetland based on its functions.  Old-growth forests (west of Cascade crest): Stands of at least two tree species, forming a multi-layered canopy with occasional small openings; with at least 8 trees/ac (20 trees/ha) that are at least 200 years of age OR have a diameter at breast height (dbh) of 32 in (81 cm) or more.  Mature forests (west of the Cascade Crest): Stands where the largest trees are 80- 200 years old OR the species that make up the canopy have an average diameter (dbh) exceeding 21 in (53 cm). Yes = Category I No = Not a forested wetland for this section Cat. I SC 5.0. Wetlands in Coastal Lagoons Does the wetland meet all of the following criteria of a wetland in a coastal lagoon?  The wetland lies in a depression adjacent to marine waters that is wholly or partially separated from marine waters by sandbanks, gravel banks, shingle, or, less frequently, rocks  The lagoon in which the wetland is located contains ponded water that is saline or brackish (> 0.5 ppt) during most of the year in at least a portion of the lagoon (needs to be measured near the bottom) Yes – Go to SC 5.1 No = Not a wetland in a coastal lagoon SC 5.1. Does the wetland meet all of the following three conditions?  The wetland is relatively undisturbed (has no diking, ditching, filling, cultivation, grazing), and has less than 20% cover of aggressive, opportunistic plant species (see list of species on p. 100).  At least ¾ of the landward edge of the wetland has a 100 ft buffer of shrub, forest, or un -grazed or un- mowed grassland.  The wetland is larger than 1/10 ac (4350 ft2) Yes = Category I No = Category II Cat. I Cat. II SC 6.0. Interdunal Wetlands Is the wetland west of the 1889 line (also called the Western Boundary of Upland Ownership or WBUO)? If you answer yes you will still need to rate the wetland based on its habitat functions. In practical terms that means the following geographic areas:  Long Beach Peninsula: Lands west of SR 103  Grayland-Westport: Lands west of SR 105  Ocean Shores-Copalis: Lands west of SR 115 and SR 109 Yes – Go to SC 6.1 No = not an interdunal wetland for rating SC 6.1. Is the wetland 1 ac or larger and scores an 8 or 9 for the habitat functions on the form (rates H,H,H or H,H,M for the three aspects of function)? Yes = Category I No – Go to SC 6.2 SC 6.2. Is the wetland 1 ac or larger, or is it in a mosaic of wetlands that is 1 ac or larger? Yes = Category II No – Go to SC 6.3 SC 6.3. Is the unit between 0.1 and 1 ac, or is it in a mosaic of wetlands that is between 0.1 and 1 ac? Yes = Category III No = Category IV Cat I Cat. II Cat. III Cat. IV Category of wetland based on Special Characteristics If you answered No for all types, enter “Not Applicable” on Summary Form Wetland C Notes: - Entire wetland is emergent Cowardin class - Entire wetland is saturated - Dense, uncut vegetation is ~ 10% of wetland - Dense rigid vegetation ~10% of wetland Wetland C Rating Figure 1. Cowardin Class, Hydroperiod, Pollutant Generating Surfaces Pollutant generating surface within 150 foot buffer 100% of 1 km buffer= high intensity land use Wetland C Rating Figure 2. One Kilometer Buffer Land Use Intensity Wetland C Rating Figure 3. Section 303(d) Ecology Screen Shot Wetland C Rating Figure 3. WRIA 8 TMDL Screen Shot 21-1-22082-002 APPENDIX D IMPORTANT INFORMATION ABOUT YOUR WETLAND DELINEATION/MITIGATION AND/OR STREAM CLASSIFICATION REPORT Page 1 of 2 1/2015 SHANNON & WILSON, INC. Geotechnical and Environmental Consultants Attachment to and part of Report 21-1-20581-010 Date: September 15, 2015 To: Ms. Taine Wilton Edmonds School District #15 IMPORTANT INFORMATION ABOUT YOUR WETLAND DELINEATION/MITIGATION AND/OR STREAM CLASSIFICATION REPORT A WETLAND/STREAM REPORT IS BASED ON PROJECT-SPECIFIC FACTORS. Wetland delineation/mitigation and stream classification reports are based on a unique set of project-specific factors. These typically include the general nature of the project and property involved, its size, and its configuration; historical use and practice; the location of the project on the site and its orientation; and the level of additional risk the client assumed by virtue of limitations imposed upon the exploratory program. The jurisdiction of any particular wetland/stream is determined by the regulatory authority(s) issuing the permit(s). As a result, one or more agencies will have jurisdiction over a particular wetland or stream with sometimes confusing regulations. It is necessary to involve a consultant who understands which agency(s) has jurisdiction over a particular wetland/stream and what the agency(s) permitting requirements are for that wetland/stream. To help reduce or avoid potential costly problems, have the consultant determine how any factors or regulations (which can change subsequent to the report) may affect the recommendations. Unless your consultant indicates otherwise, your report should not be used:  If the size or configuration of the proposed project is altered.  If the location or orientation of the proposed project is modified.  If there is a change of ownership.  For application to an adjacent site.  For construction at an adjacent site or on site.  Following floods, earthquakes, or other acts of nature. Wetland/stream consultants cannot accept responsibility for problems that may develop if they are not consulted after factors considered in their reports have changed. Therefore, it is incumbent upon you to notify your consultant of any factors that may have changed prior to submission of our final report. Wetland boundaries identified and stream classifications made by Shannon & Wilson are considered preliminary until validated by the U.S. Army Corps of Engineers (Corps) and/or the local jurisdictional agency. Validation by the regulating agency(s) provides a certification, usually written, that the wetland boundaries verified are the boundaries that will be regulated by the agency(s) until a specified date, or until the regulations are modified, and that the stream has been properly classified. Only the regulating agency(s) can provide this certification. MOST WETLAND/STREAM "FINDINGS" ARE PROFESSIONAL ESTIMATES. Site exploration identifies wetland/stream conditions at only those points where samples are taken and when they are taken, but the physical means of obtaining data preclude the determination of precise conditions. Consequently, the information obtained is intended to be sufficiently accurate for design, but is subject to interpretation. Additionally, data derived through sampling and subsequent laboratory testing are extrapolated by the consultant who then renders an opinion about overall conditions, the likely reaction to proposed construction activity, and/or appropriate design. Even under optimal circumstances, actual conditions may differ from those thought to exist because no consultant, no matter how qualified, and no exploration program, no matter how comprehensive, can reveal what is hidden by earth, rock, and time. Nothing can be done to prevent the unanticipated, but steps can be taken to help reduce their impacts. For this reason, most experienced owners retain their consultants through the construction or wetland mitigation/stream classification stage to identify variances, to conduct additional evaluations that may be needed, and to recommend solutions to problems encountered on site. Page 2 of 2 1/2015 WETLAND/STREAM CONDITIONS CAN CHANGE. Since natural systems are dynamic systems affected by both natural processes and human activities, changes in wetland boundaries and stream conditions may be expected. Therefore, delineated wetland boundaries and stream classifications cannot remain valid for an indefinite period of time. The Corps typically recognizes the validity of wetland delineations for a period of five years after completion. Some city and county agencies recognize the validity of wetland delineations for a period of two years. If a period of years have passed since the wetland/stream report was completed, the owner is advised to have the consultant reexamine the wetland/stream to determine if the classification is still accurate. Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or water fluctuations may also affect conditions and, thus, the continuing adequacy of the wetland/stream report. The consultant should be kept apprised of any such events and should be consulted to determine if additional evaluation is necessary. THE WETLAND/STREAM REPORT IS SUBJECT TO MISINTERPRETATION. Costly problems can occur when plans are developed based on misinterpretation of a wetland/stream report. To help avoid these problems, the consultant should be retained to work with other appropriate professionals to explain relevant wetland, stream, geological, and other findings, and to review the adequacy of plans and specifications relative to these issues. DATA FORMS SHOULD NOT BE SEPARATED FROM THE REPORT. Final data forms are developed by the consultant based on interpretation of field sheets (assembled by site personnel) and laboratory evaluation of field samples. Only final data forms customarily are included in a report. These data forms should not, under any circumstances, be drawn for inclusion in other drawings because drafters may commit errors or omissions in the transfer process. Although photographic reproduction eliminates this problem, it does nothing to reduce the possibility of misinterpreting the forms. When this occurs, delays, disputes, and unanticipated costs are frequently the result. To reduce the likelihood of data form misinterpretation, contractors, engineers, and planners should be given ready access to the complete report. Those who do not provide such access may proceed under the mistaken impression that simply disclaiming responsibility for the accuracy of information always insulates them from attendant liability. Providing the best available information to contractors, engineers, and planners helps prevent costly problems and the adversarial attitudes that aggravate them to a disproportionate scale. READ RESPONSIBILITY CLAUSES CLOSELY. Because a wetland delineation/stream classification is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in written transmittals. These are not exculpatory clauses designed to foist the consultant's liabilities onto someone else; rather, they are definitive clauses that identify where the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions. THERE MAY BE OTHER STEPS YOU CAN TAKE TO REDUCE RISK. Your co nsultant will be pleased to discuss other techniques or designs that can be employed to mitigate the risk of delays and to provide a variety of alternatives that may be beneficial to your project. Contact your consultant for further information. Madrona School – Edmonds School District Appendix F Appendix F Wetland Hydroperiod Analysis · Figure F1: Wetland B Existing Conditions · Figure F2: Wetland B Proposed Conditions · Hydroperiod Calculations 2 3 6 2 1 2 3 7 0 4 Drawing Title Date Drawing Reference Drawn/Ck'd By Scale ASI/RFI/CSK Number 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com Project Title Client MADRONA K-8 MAHLUM ARCHITECTS WETLAND B EXISTING CONDITIONS F1 1" = 100' 11/28/2016 SJ/CB ————————————————————————————————— MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.38 Program License Number: 200410007 Project Simulation Performed on: 11/21/2016 2:56 PM Report Generation Date: 11/21/2016 2:56 PM ————————————————————————————————— Input File Name: Wetland B.fld Project Name: Madrona Analysis Title: Wetland B Comments: ———————————————— PRECIPITATION INPUT ———————————————— Computational Time Step (Minutes): 5 Extended Precipitation Time Series Selected Climatic Region Number: 13 Full Period of Record Available used for Routing Precipitation Station : 96004005 Puget East 40 in_5min 10/01/1939-10/01/2097 Evaporation Station : 961040 Puget East 40 in MAP Evaporation Scale Factor : 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 12.930 12.715 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 12.930 12.715 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 2 ---------- Subbasin : South Subbasin ---------- -------Area(Acres) -------- Till Forest 3.955 Till Pasture 0.000 Till Grass 2.156 Outwash Forest 0.000 Page 1 of 31 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 2 0.000 Impervious 0.653 ---------------------------------------------- Subbasin Total 6.764 ---------- Subbasin : North Subbasin ---------- -------Area(Acres) -------- Till Forest 2.572 Till Pasture 0.000 Till Grass 1.709 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 2 0.000 Impervious 1.885 ---------------------------------------------- Subbasin Total 6.166 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 2 ---------- Subbasin : South Subbasin ---------- -------Area(Acres) -------- Till Forest 3.955 Till Pasture 0.000 Till Grass 0.986 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 2 0.000 Impervious 1.196 ---------------------------------------------- Subbasin Total 6.137 ---------- Subbasin : North Subbasin ---------- -------Area(Acres) -------- Till Forest 2.572 Till Pasture 0.000 Till Grass 2.455 Outwash Forest 0.000 Outwash Pasture 0.000 Outwash Grass 0.000 Wetland 0.000 Green Roof 0.000 User 2 0.000 Page 2 of 31 Impervious 1.551 ---------------------------------------------- Subbasin Total 6.578 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 2 ------------------------------------------ Link Name: Wetland B - South Link Type: Structure Downstream Link: None User Specified Elevation Volume Table Used Elevation (ft) Pond Volume (cu-ft) 424.00 0. 425.00 359. 426.00 2395. 427.00 8143. 428.00 20539. Constant Infiltration Option Used Infiltration Rate (in/hr): 0.03 Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 1.00 Common Length (ft) : 0.000 Riser Crest Elevation : 430.00 ft Hydraulic Structure Geometry Number of Devices: 1 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 424.19 Diameter (in) : 18.00 Orientation : Vertical Elbow : No ------------------------------------------ Link Name: Wetland B - North Link Type: Structure Downstream Link Name: Wetland B - South User Specified Elevation Volume Table Used Elevation (ft) Pond Volume (cu-ft) 430.00 0. 431.00 1498. 432.00 7141. Page 3 of 31 433.00 17684. Constant Infiltration Option Used Infiltration Rate (in/hr): 0.03 Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 1.00 Common Length (ft) : 0.000 Riser Crest Elevation : 435.00 ft Hydraulic Structure Geometry Number of Devices: 1 --- Device Number 1 --- Device Type : Trapezoidal Broad Crested Weir (Independent of Riser) Invert Elevation (ft) : 431.64 Length (ft) : 8.00 Side Slope (Z) (ft/ft) : 9.70 ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 2 ------------------------------------------ Link Name: Wetland B - North Link Type: Structure Downstream Link Name: Wetland B - South User Specified Elevation Volume Table Used Elevation (ft) Pond Volume (cu-ft) 430.00 0. 431.00 1498. 432.00 7141. 433.00 17684. Constant Infiltration Option Used Infiltration Rate (in/hr): 0.03 Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 1.00 Common Length (ft) : 0.000 Riser Crest Elevation : 435.00 ft Hydraulic Structure Geometry Number of Devices: 1 --- Device Number 1 --- Device Type : Trapezoidal Broad Crested Weir (Independent of Riser) Invert Elevation (ft) : 431.64 Page 4 of 31 Length (ft) : 8.00 Side Slope (Z) (ft/ft) : 9.70 ------------------------------------------ Link Name: Wetland B - South Link Type: Structure Downstream Link: None User Specified Elevation Volume Table Used Elevation (ft) Pond Volume (cu-ft) 424.00 0. 425.00 359. 426.00 2395. 427.00 8143. 428.00 20539. Constant Infiltration Option Used Infiltration Rate (in/hr): 0.03 Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 1.00 Common Length (ft) : 0.000 Riser Crest Elevation : 430.00 ft Hydraulic Structure Geometry Number of Devices: 1 ---Device Number 1 --- Device Type : Circular Orifice Control Elevation (ft) : 424.19 Diameter (in) : 18.00 Orientation : Vertical Elbow : No **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 2 Number of Links: 2 ********** Subbasin: South Subbasin ********** Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.589 5-Year 0.947 10-Year 1.168 25-Year 1.738 50-Year 2.218 100-Year 2.656 Page 5 of 31 200-Year 3.209 ********** Subbasin: North Subbasin ********** Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 1.088 5-Year 1.503 10-Year 1.828 25-Year 2.376 50-Year 3.647 100-Year 4.093 200-Year 4.238 ********** Link: Wetland B - South ********** Link Inflow Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 1.348 5-Year 1.925 10-Year 2.571 25-Year 3.260 50-Year 4.225 100-Year 5.580 200-Year 5.823 ********** Link: Wetland B - South ********** Link WSEL Stats WSEL Frequency Data(ft) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) WSEL Peak (ft) ====================================== 1.05-Year 424.526 1.11-Year 424.554 1.25-Year 424.589 2.00-Year 424.706 3.33-Year 424.768 5-Year 424.815 10-Year 424.920 25-Year 425.015 50-Year 425.144 100-Year 425.283 ********** Link: Wetland B - North ********** Link Inflow Frequency Stats Page 6 of 31 Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 1.088 5-Year 1.503 10-Year 1.828 25-Year 2.376 50-Year 3.647 100-Year 4.093 200-Year 4.238 ********** Link: Wetland B - North ********** Link Outflow 1 Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.860 5-Year 1.188 10-Year 1.553 25-Year 1.906 50-Year 2.480 100-Year 3.177 200-Year 3.310 ********** Link: Wetland B - North ********** Link WSEL Stats WSEL Frequency Data(ft) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) WSEL Peak (ft) ====================================== 1.05-Year 431.706 1.11-Year 431.711 1.25-Year 431.718 2.00-Year 431.745 3.33-Year 431.760 5-Year 431.770 10-Year 431.793 25-Year 431.814 50-Year 431.845 100-Year 431.880 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 2 Number of Links: 2 ********** Subbasin: South Subbasin ********** Flood Frequency Data(cfs) Page 7 of 31 (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.708 5-Year 0.974 10-Year 1.223 25-Year 1.587 50-Year 2.265 100-Year 2.668 200-Year 2.969 ********** Subbasin: North Subbasin ********** Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.991 5-Year 1.430 10-Year 1.874 25-Year 2.473 50-Year 3.664 100-Year 4.269 200-Year 4.295 ********** Link: Wetland B - North ********** Link Inflow Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.991 5-Year 1.430 10-Year 1.874 25-Year 2.473 50-Year 3.664 100-Year 4.269 200-Year 4.295 ********** Link: Wetland B - North ********** Link Outflow 1 Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 0.795 5-Year 1.134 10-Year 1.518 25-Year 1.884 50-Year 2.455 100-Year 3.380 Page 8 of 31 200-Year 3.428 ********** Link: Wetland B - North ********** Link WSEL Stats WSEL Frequency Data(ft) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) WSEL Peak (ft) ====================================== 1.05-Year 431.700 1.11-Year 431.705 1.25-Year 431.712 2.00-Year 431.740 3.33-Year 431.756 5-Year 431.767 10-Year 431.791 25-Year 431.812 50-Year 431.844 100-Year 431.888 ********** Link: Wetland B - South ********** Link Inflow Frequency Stats Flood Frequency Data(cfs) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) Flood Peak (cfs) ====================================== 2-Year 1.385 5-Year 1.940 10-Year 2.555 25-Year 3.202 50-Year 4.061 100-Year 5.505 200-Year 5.676 ********** Link: Wetland B - South ********** Link WSEL Stats WSEL Frequency Data(ft) (Recurrence Interval Computed Using Gringorten Plotting Position) Tr (yrs) WSEL Peak (ft) ====================================== 1.05-Year 424.538 1.11-Year 424.566 1.25-Year 424.604 2.00-Year 424.709 3.33-Year 424.775 5-Year 424.817 10-Year 424.917 25-Year 425.008 50-Year 425.127 100-Year 425.279 Page 9 of 31 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perlnd Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: South Subbasin 943.969 Subbasin: North Subbasin 651.361 Link: Wetland B - South 0.000 Link: Wetland B - North 364.540 _____________________________________ Total: 1959.870 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) ----------------------------------------------------------------------------------------------- Subbasin: South Subbasin 801.083 Subbasin: North Subbasin 742.467 Link: Wetland B - North 359.759 Link: Wetland B - South 0.000 _____________________________________ Total: 1903.309 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 12.404 ac-ft/year, Post Developed: 12.046 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 2 ********** Link: Wetland B - South ********** Basic Wet Pond Volume (91% Exceedance): 23443. cu-ft Computed Large Wet Pond Volume, 1.5*Basic Volume: 35165. cu-ft Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 2150.93 Inflow Volume Including PPT-Evap (ac-ft): 2150.93 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 2156.17 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ********** Link: Wetland B - North ********** Basic Wet Pond Volume (91% Exceedance): 12484. cu-ft Computed Large Wet Pond Volume, 1.5*Basic Volume: 18726. cu-ft Page 10 of 31 Time to Infiltrate 91% Treatment Volume, (Hours): 4151.11 Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 1424.67 Inflow Volume Including PPT-Evap (ac-ft): 1424.67 Total Runoff Infiltrated (ac-ft): 364.54, 25.59% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 1063.07 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 25.59% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 2 ********** Link: Wetland B - North ********** Basic Wet Pond Volume (91% Exceedance): 12298. cu-ft Computed Large Wet Pond Volume, 1.5*Basic Volume: 18447. cu-ft Time to Infiltrate 91% Treatment Volume, (Hours): 4166.12 Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 1424.80 Inflow Volume Including PPT-Evap (ac-ft): 1424.80 Total Runoff Infiltrated (ac-ft): 359.76, 25.25% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 1067.30 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 25.25% ********** Link: Wetland B - South ********** Basic Wet Pond Volume (91% Exceedance): 23291. cu-ft Computed Large Wet Pond Volume, 1.5*Basic Volume: 34936. cu-ft Infiltration/Filtration Statistics-------------------- Inflow Volume (ac-ft): 2163.57 Inflow Volume Including PPT-Evap (ac-ft): 2163.57 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 2169.36 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: Wetland B - South Scenario Postdeveloped Compliance Link: Wetland B - South *** Point of Compliance Flow Frequency Data *** Page 11 of 31 Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ---------------------------------------------------------------------------------------------------------------------- 2-Year 1.331 2-Year 1.348 5-Year 1.900 5-Year 1.911 10-Year 2.523 10-Year 2.508 25-Year 3.165 25-Year 3.117 50-Year 4.020 50-Year 3.901 100-Year 5.002 100-Year 4.971 200-Year 5.166 200-Year 5.098 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals ***********Wetland Hydroperiod Analysis Results ************* Predeveloped Wetland Location: Wetland B - North Postdeveloped Wetland Location: Wetland B - North ***********Mean Water Level Fluctuation Results (ft) ************* Month Predeveloped Postdeveloped ----------------------------------------------------------------------------------------------- Oct 0.5300 0.5242 Nov 0.1175 0.1105 Dec 0.0946 0.0884 Jan 0.1155 0.1096 Feb 0.1048 0.0993 Mar 0.1194 0.1125 Apr 0.1334 0.1274 May 0.1813 0.1742 Jun 0.2064 0.1992 Jul 0.1996 0.1922 Aug 0.1963 0.1875 Sep 0.2352 0.2290 Ann 0.1862 0.1795 ***********Stage Excursion Results ************* Stage Excursions Threshold (ft): 0.500 Avg Number of Stage Excursions Per Year: 0.000 WY No. Excursions Max (ft) Max Dur (hrs) Avg Duration (hrs) ------------------------------------------------------------------------------------------------------------------------------------------- 1940 00 0.0000 0.0 0.0 1941 00 0.0000 0.0 0.0 1942 00 0.0000 0.0 0.0 1943 00 0.0000 0.0 0.0 1944 00 0.0000 0.0 0.0 1945 00 0.0000 0.0 0.0 1946 00 0.0000 0.0 0.0 1947 00 0.0000 0.0 0.0 1948 00 0.0000 0.0 0.0 1949 00 0.0000 0.0 0.0 1950 00 0.0000 0.0 0.0 1951 00 0.0000 0.0 0.0 1952 00 0.0000 0.0 0.0 Page 12 of 31 1953 00 0.0000 0.0 0.0 1954 00 0.0000 0.0 0.0 1955 00 0.0000 0.0 0.0 1956 00 0.0000 0.0 0.0 1957 00 0.0000 0.0 0.0 1958 00 0.0000 0.0 0.0 1959 00 0.0000 0.0 0.0 1960 00 0.0000 0.0 0.0 1961 00 0.0000 0.0 0.0 1962 00 0.0000 0.0 0.0 1963 00 0.0000 0.0 0.0 1964 00 0.0000 0.0 0.0 1965 00 0.0000 0.0 0.0 1966 00 0.0000 0.0 0.0 1967 00 0.0000 0.0 0.0 1968 00 0.0000 0.0 0.0 1969 00 0.0000 0.0 0.0 1970 00 0.0000 0.0 0.0 1971 00 0.0000 0.0 0.0 1972 00 0.0000 0.0 0.0 1973 00 0.0000 0.0 0.0 1974 00 0.0000 0.0 0.0 1975 00 0.0000 0.0 0.0 1976 00 0.0000 0.0 0.0 1977 00 0.0000 0.0 0.0 1978 00 0.0000 0.0 0.0 1979 00 0.0000 0.0 0.0 1980 00 0.0000 0.0 0.0 1981 00 0.0000 0.0 0.0 1982 00 0.0000 0.0 0.0 1983 00 0.0000 0.0 0.0 1984 00 0.0000 0.0 0.0 1985 00 0.0000 0.0 0.0 1986 00 0.0000 0.0 0.0 1987 00 0.0000 0.0 0.0 1988 00 0.0000 0.0 0.0 1989 00 0.0000 0.0 0.0 1990 00 0.0000 0.0 0.0 1991 00 0.0000 0.0 0.0 1992 00 0.0000 0.0 0.0 1993 00 0.0000 0.0 0.0 1994 00 0.0000 0.0 0.0 1995 00 0.0000 0.0 0.0 1996 00 0.0000 0.0 0.0 1997 00 0.0000 0.0 0.0 1998 00 0.0000 0.0 0.0 1999 00 0.0000 0.0 0.0 2000 00 0.0000 0.0 0.0 2001 00 0.0000 0.0 0.0 2002 00 0.0000 0.0 0.0 2003 00 0.0000 0.0 0.0 2004 00 0.0000 0.0 0.0 2005 00 0.0000 0.0 0.0 2006 00 0.0000 0.0 0.0 2007 00 0.0000 0.0 0.0 2008 00 0.0000 0.0 0.0 Page 13 of 31 2009 00 0.0000 0.0 0.0 2010 00 0.0000 0.0 0.0 2011 00 0.0000 0.0 0.0 2012 00 0.0000 0.0 0.0 2013 00 0.0000 0.0 0.0 2014 00 0.0000 0.0 0.0 2015 00 0.0000 0.0 0.0 2016 00 0.0000 0.0 0.0 2017 00 0.0000 0.0 0.0 2018 00 0.0000 0.0 0.0 2019 00 0.0000 0.0 0.0 2020 00 0.0000 0.0 0.0 2021 00 0.0000 0.0 0.0 2022 00 0.0000 0.0 0.0 2023 00 0.0000 0.0 0.0 2024 00 0.0000 0.0 0.0 2025 00 0.0000 0.0 0.0 2026 00 0.0000 0.0 0.0 2027 00 0.0000 0.0 0.0 2028 00 0.0000 0.0 0.0 2029 00 0.0000 0.0 0.0 2030 00 0.0000 0.0 0.0 2031 00 0.0000 0.0 0.0 2032 00 0.0000 0.0 0.0 2033 00 0.0000 0.0 0.0 2034 00 0.0000 0.0 0.0 2035 00 0.0000 0.0 0.0 2036 00 0.0000 0.0 0.0 2037 00 0.0000 0.0 0.0 2038 00 0.0000 0.0 0.0 2039 00 0.0000 0.0 0.0 2040 00 0.0000 0.0 0.0 2041 00 0.0000 0.0 0.0 2042 00 0.0000 0.0 0.0 2043 00 0.0000 0.0 0.0 2044 00 0.0000 0.0 0.0 2045 00 0.0000 0.0 0.0 2046 00 0.0000 0.0 0.0 2047 00 0.0000 0.0 0.0 2048 00 0.0000 0.0 0.0 2049 00 0.0000 0.0 0.0 2050 00 0.0000 0.0 0.0 2051 00 0.0000 0.0 0.0 2052 00 0.0000 0.0 0.0 2053 00 0.0000 0.0 0.0 2054 00 0.0000 0.0 0.0 2055 00 0.0000 0.0 0.0 2056 00 0.0000 0.0 0.0 2057 00 0.0000 0.0 0.0 2058 00 0.0000 0.0 0.0 2059 00 0.0000 0.0 0.0 2060 00 0.0000 0.0 0.0 2061 00 0.0000 0.0 0.0 2062 00 0.0000 0.0 0.0 2063 00 0.0000 0.0 0.0 2064 00 0.0000 0.0 0.0 Page 14 of 31 2065 00 0.0000 0.0 0.0 2066 00 0.0000 0.0 0.0 2067 00 0.0000 0.0 0.0 2068 00 0.0000 0.0 0.0 2069 00 0.0000 0.0 0.0 2070 00 0.0000 0.0 0.0 2071 00 0.0000 0.0 0.0 2072 00 0.0000 0.0 0.0 2073 00 0.0000 0.0 0.0 2074 00 0.0000 0.0 0.0 2075 00 0.0000 0.0 0.0 2076 00 0.0000 0.0 0.0 2077 00 0.0000 0.0 0.0 2078 00 0.0000 0.0 0.0 2079 00 0.0000 0.0 0.0 2080 00 0.0000 0.0 0.0 2081 00 0.0000 0.0 0.0 2082 00 0.0000 0.0 0.0 2083 00 0.0000 0.0 0.0 2084 00 0.0000 0.0 0.0 2085 00 0.0000 0.0 0.0 2086 00 0.0000 0.0 0.0 2087 00 0.0000 0.0 0.0 2088 00 0.0000 0.0 0.0 2089 00 0.0000 0.0 0.0 2090 00 0.0000 0.0 0.0 2091 00 0.0000 0.0 0.0 2092 00 0.0000 0.0 0.0 2093 00 0.0000 0.0 0.0 2094 00 0.0000 0.0 0.0 2095 00 0.0000 0.0 0.0 2096 00 0.0000 0.0 0.0 2097 00 0.0000 0.0 0.0 ***********No Water (Dry) Excursion Results ************* Wetland Dry when Stage Drops Below (ft): 0.010 Dry Excursion Duration (hrs) WY Predeveloped Postdeveloped ------------------------------------------------------------------------------------------------------------------------------------------- 1940 460.8 460.9 1941 0.0 0.0 1942 0.0 0.0 1943 0.0 0.0 1944 0.0 0.0 1945 0.0 0.0 1946 78.5 98.3 1947 0.0 0.0 1948 0.0 0.0 1949 315.8 338.5 1950 0.0 0.0 1951 709.7 777.1 1952 0.0 0.0 1953 0.7 38.4 1954 0.0 0.0 1955 0.0 0.0 Page 15 of 31 1956 0.0 0.0 1957 0.0 0.0 1958 246.1 300.2 1959 0.0 0.0 1960 152.8 199.7 1961 0.0 0.0 1962 0.0 0.0 1963 0.0 0.0 1964 0.0 0.0 1965 0.0 0.0 1966 0.0 0.0 1967 370.1 361.9 1968 0.0 0.0 1969 0.0 0.0 1970 0.0 0.0 1971 0.0 0.0 1972 0.0 0.0 1973 0.0 0.0 1974 0.0 0.0 1975 85.6 125.3 1976 0.0 0.0 1977 0.0 0.0 1978 0.0 0.0 1979 0.0 0.0 1980 0.0 0.0 1981 0.0 0.0 1982 0.0 0.0 1983 0.0 0.0 1984 0.0 0.0 1985 0.0 0.0 1986 81.9 141.7 1987 0.0 0.0 1988 0.0 0.0 1989 0.0 0.0 1990 0.0 0.0 1991 0.0 0.0 1992 0.0 0.0 1993 181.2 177.3 1994 130.8 132.4 1995 0.0 0.0 1996 0.0 0.0 1997 0.0 0.0 1998 711.4 760.2 1999 0.0 0.0 2000 5.0 43.2 2001 0.0 0.0 2002 561.3 618.3 2003 251.9 252.1 2004 783.5 978.3 2005 0.0 0.0 2006 0.0 0.0 2007 0.0 0.0 2008 0.0 0.0 2009 0.0 0.0 2010 0.0 0.0 2011 339.3 374.7 Page 16 of 31 2012 296.4 283.9 2013 46.7 83.0 2014 0.0 0.0 2015 0.0 0.0 2016 0.0 0.0 2017 367.3 411.5 2018 318.1 306.3 2019 119.9 155.8 2020 355.2 390.4 2021 0.0 0.0 2022 68.6 69.2 2023 242.8 243.6 2024 0.0 15.2 2025 0.0 0.0 2026 35.3 93.8 2027 594.2 641.1 2028 0.0 0.0 2029 524.6 514.9 2030 587.6 622.7 2031 29.8 20.1 2032 33.6 58.0 2033 88.9 88.2 2034 0.0 0.0 2035 0.0 0.0 2036 0.0 0.0 2037 0.0 0.0 2038 0.0 0.0 2039 0.0 0.0 2040 268.5 295.4 2041 733.4 745.9 2042 0.0 0.0 2043 0.0 0.0 2044 276.9 267.6 2045 0.0 0.0 2046 325.3 327.3 2047 139.4 151.8 2048 1255.4 1347.9 2049 0.0 0.0 2050 0.0 0.0 2051 100.0 99.9 2052 58.9 114.5 2053 0.0 0.0 2054 939.3 993.0 2055 0.0 0.0 2056 0.0 0.0 2057 0.0 0.0 2058 676.8 692.5 2059 0.0 0.0 2060 0.0 0.0 2061 0.0 0.0 2062 0.0 0.0 2063 0.0 0.0 2064 0.0 0.0 2065 0.0 0.0 2066 0.0 0.0 2067 0.0 0.0 Page 17 of 31 2068 0.0 0.0 2069 0.0 0.0 2070 0.0 0.0 2071 0.0 0.0 2072 0.0 0.0 2073 0.0 0.0 2074 0.0 0.0 2075 0.0 0.0 2076 0.0 0.0 2077 0.0 0.0 2078 0.0 0.0 2079 0.0 0.0 2080 0.0 0.0 2081 0.0 0.0 2082 0.0 0.0 2083 0.0 0.0 2084 0.0 0.0 2085 0.0 0.0 2086 61.5 59.7 2087 0.0 0.0 2088 0.0 0.0 2089 0.0 0.0 2090 7.8 28.3 2091 0.0 0.0 2092 0.0 0.0 2093 0.0 0.0 2094 245.7 279.1 2095 0.0 0.0 2096 0.0 0.0 2097 6.0 6.0 ***********Amphibian Season Analysis************* Season Begins : 02/01 Season Ends : 05/31 Amphibian Stage Excursions Threshold (ft): 0.250 WY Max Excursion (ft) Max 30-Day Excursion (hrs) ------------------------------------------------------------------------------------------------------------------------------------------- 1940 0.000 0.0 1941 0.000 0.0 1942 0.000 0.0 1943 0.000 0.0 1944 0.000 0.0 1945 0.000 0.0 1946 0.000 0.0 1947 0.000 0.0 1948 0.000 0.0 1949 0.000 0.0 1950 0.000 0.0 1951 0.000 0.0 1952 0.000 0.0 1953 0.000 0.0 1954 0.000 0.0 1955 0.000 0.0 1956 0.000 0.0 Page 18 of 31 1957 0.000 0.0 1958 0.000 0.0 1959 0.000 0.0 1960 0.000 0.0 1961 0.000 0.0 1962 0.000 0.0 1963 0.000 0.0 1964 0.000 0.0 1965 0.000 0.0 1966 0.000 0.0 1967 0.000 0.0 1968 0.000 0.0 1969 0.000 0.0 1970 0.000 0.0 1971 0.000 0.0 1972 0.000 0.0 1973 0.000 0.0 1974 0.000 0.0 1975 0.000 0.0 1976 0.000 0.0 1977 0.000 0.0 1978 0.000 0.0 1979 0.000 0.0 1980 0.000 0.0 1981 0.000 0.0 1982 0.000 0.0 1983 0.000 0.0 1984 0.000 0.0 1985 0.000 0.0 1986 0.000 0.0 1987 0.000 0.0 1988 0.000 0.0 1989 0.000 0.0 1990 0.000 0.0 1991 0.000 0.0 1992 0.000 0.0 1993 0.000 0.0 1994 0.000 0.0 1995 0.000 0.0 1996 0.000 0.0 1997 0.000 0.0 1998 0.000 0.0 1999 0.000 0.0 2000 0.000 0.0 2001 0.000 0.0 2002 0.000 0.0 2003 0.000 0.0 2004 0.000 0.0 2005 0.000 0.0 2006 0.000 0.0 2007 0.000 0.0 2008 0.000 0.0 2009 0.000 0.0 2010 0.000 0.0 2011 0.000 0.0 2012 0.000 0.0 Page 19 of 31 2013 0.000 0.0 2014 0.000 0.0 2015 0.000 0.0 2016 0.000 0.0 2017 0.000 0.0 2018 0.000 0.0 2019 0.000 0.0 2020 0.000 0.0 2021 0.000 0.0 2022 0.000 0.0 2023 0.000 0.0 2024 0.000 0.0 2025 0.000 0.0 2026 0.000 0.0 2027 0.000 0.0 2028 0.000 0.0 2029 0.000 0.0 2030 0.000 0.0 2031 0.000 0.0 2032 0.000 0.0 2033 0.000 0.0 2034 0.000 0.0 2035 0.000 0.0 2036 0.000 0.0 2037 0.000 0.0 2038 0.000 0.0 2039 0.000 0.0 2040 0.000 0.0 2041 0.000 0.0 2042 0.000 0.0 2043 0.000 0.0 2044 0.000 0.0 2045 0.000 0.0 2046 0.000 0.0 2047 0.000 0.0 2048 0.000 0.0 2049 0.000 0.0 2050 0.000 0.0 2051 0.000 0.0 2052 0.000 0.0 2053 0.000 0.0 2054 0.000 0.0 2055 0.000 0.0 2056 0.000 0.0 2057 0.000 0.0 2058 0.000 0.0 2059 0.000 0.0 2060 0.000 0.0 2061 0.000 0.0 2062 0.000 0.0 2063 0.000 0.0 2064 0.000 0.0 2065 0.000 0.0 2066 0.000 0.0 2067 0.000 0.0 2068 0.000 0.0 Page 20 of 31 2069 0.000 0.0 2070 0.000 0.0 2071 0.000 0.0 2072 0.000 0.0 2073 0.000 0.0 2074 0.000 0.0 2075 0.000 0.0 2076 0.000 0.0 2077 0.000 0.0 2078 0.000 0.0 2079 0.000 0.0 2080 0.000 0.0 2081 0.000 0.0 2082 0.000 0.0 2083 0.000 0.0 2084 0.000 0.0 2085 0.000 0.0 2086 0.000 0.0 2087 0.000 0.0 2088 0.000 0.0 2089 0.000 0.0 2090 0.000 0.0 2091 0.000 0.0 2092 0.000 0.0 2093 0.000 0.0 2094 0.000 0.0 2095 0.000 0.0 2096 0.000 0.0 2097 0.000 0.0 Page 21 of 31 ***********Wetland Hydroperiod Analysis Results ************* Predeveloped Wetland Location: Wetland B - South Postdeveloped Wetland Location: Wetland B - South ***********Mean Water Level Fluctuation Results (ft) ************* Month Predeveloped Postdeveloped ----------------------------------------------------------------------------------------------- Oct 0.4631 0.4730 Nov 0.1739 0.1835 Dec 0.1565 0.1642 Jan 0.1442 0.1507 Feb 0.1447 0.1516 Mar 0.1470 0.1540 Apr 0.1224 0.1324 May 0.0965 0.1086 Jun 0.0815 0.0925 Jul 0.0428 0.0507 Aug 0.0447 0.0538 Sep 0.0861 0.0977 Ann 0.1419 0.1511 ***********Stage Excursion Results ************* Stage Excursions Threshold (ft): 0.500 Avg Number of Stage Excursions Per Year: 0.000 WY No. Excursions Max (ft) Max Dur (hrs) Avg Duration (hrs) ------------------------------------------------------------------------------------------------------------------------------------------- 1940 00 0.0000 0.0 0.0 1941 00 0.0000 0.0 0.0 1942 00 0.0000 0.0 0.0 1943 00 0.0000 0.0 0.0 1944 00 0.0000 0.0 0.0 1945 00 0.0000 0.0 0.0 1946 00 0.0000 0.0 0.0 1947 00 0.0000 0.0 0.0 1948 00 0.0000 0.0 0.0 1949 00 0.0000 0.0 0.0 1950 00 0.0000 0.0 0.0 1951 00 0.0000 0.0 0.0 1952 00 0.0000 0.0 0.0 1953 00 0.0000 0.0 0.0 1954 00 0.0000 0.0 0.0 1955 00 0.0000 0.0 0.0 1956 00 0.0000 0.0 0.0 1957 00 0.0000 0.0 0.0 1958 00 0.0000 0.0 0.0 1959 00 0.0000 0.0 0.0 1960 00 0.0000 0.0 0.0 1961 00 0.0000 0.0 0.0 1962 00 0.0000 0.0 0.0 1963 00 0.0000 0.0 0.0 1964 00 0.0000 0.0 0.0 1965 00 0.0000 0.0 0.0 1966 00 0.0000 0.0 0.0 1967 00 0.0000 0.0 0.0 Page 22 of 31 1968 00 0.0000 0.0 0.0 1969 00 0.0000 0.0 0.0 1970 00 0.0000 0.0 0.0 1971 00 0.0000 0.0 0.0 1972 00 0.0000 0.0 0.0 1973 00 0.0000 0.0 0.0 1974 00 0.0000 0.0 0.0 1975 00 0.0000 0.0 0.0 1976 00 0.0000 0.0 0.0 1977 00 0.0000 0.0 0.0 1978 00 0.0000 0.0 0.0 1979 00 0.0000 0.0 0.0 1980 00 0.0000 0.0 0.0 1981 00 0.0000 0.0 0.0 1982 00 0.0000 0.0 0.0 1983 00 0.0000 0.0 0.0 1984 00 0.0000 0.0 0.0 1985 00 0.0000 0.0 0.0 1986 00 0.0000 0.0 0.0 1987 00 0.0000 0.0 0.0 1988 00 0.0000 0.0 0.0 1989 00 0.0000 0.0 0.0 1990 00 0.0000 0.0 0.0 1991 00 0.0000 0.0 0.0 1992 00 0.0000 0.0 0.0 1993 00 0.0000 0.0 0.0 1994 00 0.0000 0.0 0.0 1995 00 0.0000 0.0 0.0 1996 00 0.0000 0.0 0.0 1997 00 0.0000 0.0 0.0 1998 00 0.0000 0.0 0.0 1999 00 0.0000 0.0 0.0 2000 00 0.0000 0.0 0.0 2001 00 0.0000 0.0 0.0 2002 00 0.0000 0.0 0.0 2003 00 0.0000 0.0 0.0 2004 00 0.0000 0.0 0.0 2005 00 0.0000 0.0 0.0 2006 00 0.0000 0.0 0.0 2007 00 0.0000 0.0 0.0 2008 00 0.0000 0.0 0.0 2009 00 0.0000 0.0 0.0 2010 00 0.0000 0.0 0.0 2011 00 0.0000 0.0 0.0 2012 00 0.0000 0.0 0.0 2013 00 0.0000 0.0 0.0 2014 00 0.0000 0.0 0.0 2015 00 0.0000 0.0 0.0 2016 00 0.0000 0.0 0.0 2017 00 0.0000 0.0 0.0 2018 00 0.0000 0.0 0.0 2019 00 0.0000 0.0 0.0 2020 00 0.0000 0.0 0.0 2021 00 0.0000 0.0 0.0 2022 00 0.0000 0.0 0.0 2023 00 0.0000 0.0 0.0 Page 23 of 31 2024 00 0.0000 0.0 0.0 2025 00 0.0000 0.0 0.0 2026 00 0.0000 0.0 0.0 2027 00 0.0000 0.0 0.0 2028 00 0.0000 0.0 0.0 2029 00 0.0000 0.0 0.0 2030 00 0.0000 0.0 0.0 2031 00 0.0000 0.0 0.0 2032 00 0.0000 0.0 0.0 2033 00 0.0000 0.0 0.0 2034 00 0.0000 0.0 0.0 2035 00 0.0000 0.0 0.0 2036 00 0.0000 0.0 0.0 2037 00 0.0000 0.0 0.0 2038 00 0.0000 0.0 0.0 2039 00 0.0000 0.0 0.0 2040 00 0.0000 0.0 0.0 2041 00 0.0000 0.0 0.0 2042 00 0.0000 0.0 0.0 2043 00 0.0000 0.0 0.0 2044 00 0.0000 0.0 0.0 2045 00 0.0000 0.0 0.0 2046 00 0.0000 0.0 0.0 2047 00 0.0000 0.0 0.0 2048 00 0.0000 0.0 0.0 2049 00 0.0000 0.0 0.0 2050 00 0.0000 0.0 0.0 2051 00 0.0000 0.0 0.0 2052 00 0.0000 0.0 0.0 2053 00 0.0000 0.0 0.0 2054 00 0.0000 0.0 0.0 2055 00 0.0000 0.0 0.0 2056 00 0.0000 0.0 0.0 2057 00 0.0000 0.0 0.0 2058 00 0.0000 0.0 0.0 2059 00 0.0000 0.0 0.0 2060 00 0.0000 0.0 0.0 2061 00 0.0000 0.0 0.0 2062 00 0.0000 0.0 0.0 2063 00 0.0000 0.0 0.0 2064 00 0.0000 0.0 0.0 2065 00 0.0000 0.0 0.0 2066 00 0.0000 0.0 0.0 2067 00 0.0000 0.0 0.0 2068 00 0.0000 0.0 0.0 2069 00 0.0000 0.0 0.0 2070 00 0.0000 0.0 0.0 2071 00 0.0000 0.0 0.0 2072 00 0.0000 0.0 0.0 2073 00 0.0000 0.0 0.0 2074 00 0.0000 0.0 0.0 2075 00 0.0000 0.0 0.0 2076 00 0.0000 0.0 0.0 2077 00 0.0000 0.0 0.0 2078 00 0.0000 0.0 0.0 2079 00 0.0000 0.0 0.0 Page 24 of 31 2080 00 0.0000 0.0 0.0 2081 00 0.0000 0.0 0.0 2082 00 0.0000 0.0 0.0 2083 00 0.0000 0.0 0.0 2084 00 0.0000 0.0 0.0 2085 00 0.0000 0.0 0.0 2086 00 0.0000 0.0 0.0 2087 00 0.0000 0.0 0.0 2088 00 0.0000 0.0 0.0 2089 00 0.0000 0.0 0.0 2090 00 0.0000 0.0 0.0 2091 00 0.0000 0.0 0.0 2092 00 0.0000 0.0 0.0 2093 00 0.0000 0.0 0.0 2094 00 0.0000 0.0 0.0 2095 00 0.0000 0.0 0.0 2096 00 0.0000 0.0 0.0 2097 00 0.0000 0.0 0.0 ***********No Water (Dry) Excursion Results ************* Wetland Dry when Stage Drops Below (ft): 0.010 Dry Excursion Duration (hrs) WY Predeveloped Postdeveloped ------------------------------------------------------------------------------------------------------------------------------------------- 1940 460.8 460.7 1941 0.0 0.0 1942 0.0 0.0 1943 0.0 0.0 1944 0.0 0.0 1945 0.0 0.0 1946 0.0 0.0 1947 0.0 0.0 1948 0.0 0.0 1949 0.0 0.0 1950 0.0 0.0 1951 0.0 0.0 1952 0.0 0.0 1953 0.0 0.0 1954 0.0 0.0 1955 0.0 0.0 1956 0.0 0.0 1957 0.0 0.0 1958 0.0 0.0 1959 0.0 0.0 1960 0.0 0.0 1961 0.0 0.0 1962 0.0 0.0 1963 0.0 0.0 1964 0.0 0.0 1965 0.0 0.0 1966 0.0 0.0 1967 0.0 0.0 1968 0.0 0.0 1969 0.0 0.0 1970 0.0 0.0 Page 25 of 31 1971 0.0 0.0 1972 0.0 0.0 1973 0.0 0.0 1974 0.0 0.0 1975 0.0 0.0 1976 0.0 0.0 1977 0.0 0.0 1978 0.0 0.0 1979 0.0 0.0 1980 0.0 0.0 1981 0.0 0.0 1982 0.0 0.0 1983 0.0 0.0 1984 0.0 0.0 1985 0.0 0.0 1986 0.0 0.0 1987 0.0 0.0 1988 0.0 0.0 1989 0.0 0.0 1990 0.0 0.0 1991 0.0 0.0 1992 0.0 0.0 1993 0.0 0.0 1994 0.0 0.0 1995 0.0 0.0 1996 0.0 0.0 1997 0.0 0.0 1998 0.0 0.0 1999 0.0 0.0 2000 0.0 0.0 2001 0.0 0.0 2002 0.0 0.0 2003 0.0 0.0 2004 0.0 0.0 2005 0.0 0.0 2006 0.0 0.0 2007 0.0 0.0 2008 0.0 0.0 2009 0.0 0.0 2010 0.0 0.0 2011 0.0 0.0 2012 0.0 0.0 2013 0.0 0.0 2014 0.0 0.0 2015 0.0 0.0 2016 0.0 0.0 2017 0.0 0.0 2018 0.0 0.0 2019 0.0 0.0 2020 0.0 0.0 2021 0.0 0.0 2022 0.0 0.0 2023 0.0 0.0 2024 0.0 0.0 2025 0.0 0.0 2026 0.0 0.0 Page 26 of 31 2027 0.0 0.0 2028 0.0 0.0 2029 0.0 0.0 2030 0.0 0.0 2031 0.0 0.0 2032 0.0 0.0 2033 0.0 0.0 2034 0.0 0.0 2035 0.0 0.0 2036 0.0 0.0 2037 0.0 0.0 2038 0.0 0.0 2039 0.0 0.0 2040 0.0 0.0 2041 0.0 0.0 2042 0.0 0.0 2043 0.0 0.0 2044 0.0 0.0 2045 0.0 0.0 2046 0.0 0.0 2047 0.0 0.0 2048 0.0 0.0 2049 0.0 0.0 2050 0.0 0.0 2051 0.0 0.0 2052 0.0 0.0 2053 0.0 0.0 2054 0.0 0.0 2055 0.0 0.0 2056 0.0 0.0 2057 0.0 0.0 2058 0.0 0.0 2059 0.0 0.0 2060 0.0 0.0 2061 0.0 0.0 2062 0.0 0.0 2063 0.0 0.0 2064 0.0 0.0 2065 0.0 0.0 2066 0.0 0.0 2067 0.0 0.0 2068 0.0 0.0 2069 0.0 0.0 2070 0.0 0.0 2071 0.0 0.0 2072 0.0 0.0 2073 0.0 0.0 2074 0.0 0.0 2075 0.0 0.0 2076 0.0 0.0 2077 0.0 0.0 2078 0.0 0.0 2079 0.0 0.0 2080 0.0 0.0 2081 0.0 0.0 2082 0.0 0.0 Page 27 of 31 2083 0.0 0.0 2084 0.0 0.0 2085 0.0 0.0 2086 0.0 0.0 2087 0.0 0.0 2088 0.0 0.0 2089 0.0 0.0 2090 0.0 0.0 2091 0.0 0.0 2092 0.0 0.0 2093 0.0 0.0 2094 0.0 0.0 2095 0.0 0.0 2096 0.0 0.0 2097 6.0 6.0 ***********Amphibian Season Analysis************* Season Begins : 02/01 Season Ends : 05/31 Amphibian Stage Excursions Threshold (ft): 0.250 WY Max Excursion (ft) Max 30-Day Excursion (hrs) ------------------------------------------------------------------------------------------------------------------------------------------- 1940 0.000 0.0 1941 0.000 0.0 1942 0.000 0.0 1943 0.000 0.0 1944 0.000 0.0 1945 0.000 0.0 1946 0.000 0.0 1947 0.000 0.0 1948 0.000 0.0 1949 0.000 0.0 1950 0.000 0.0 1951 0.000 0.0 1952 0.000 0.0 1953 0.000 0.0 1954 0.000 0.0 1955 0.000 0.0 1956 0.000 0.0 1957 0.000 0.0 1958 0.000 0.0 1959 0.000 0.0 1960 0.000 0.0 1961 0.000 0.0 1962 0.000 0.0 1963 0.000 0.0 1964 0.000 0.0 1965 0.000 0.0 1966 0.000 0.0 1967 0.000 0.0 1968 0.000 0.0 1969 0.000 0.0 1970 0.000 0.0 1971 0.000 0.0 Page 28 of 31 1972 0.000 0.0 1973 0.000 0.0 1974 0.000 0.0 1975 0.000 0.0 1976 0.000 0.0 1977 0.000 0.0 1978 0.000 0.0 1979 0.000 0.0 1980 0.000 0.0 1981 0.000 0.0 1982 0.000 0.0 1983 0.000 0.0 1984 0.000 0.0 1985 0.000 0.0 1986 0.000 0.0 1987 0.000 0.0 1988 0.000 0.0 1989 0.000 0.0 1990 0.000 0.0 1991 0.000 0.0 1992 0.000 0.0 1993 0.000 0.0 1994 0.000 0.0 1995 0.000 0.0 1996 0.000 0.0 1997 0.000 0.0 1998 0.000 0.0 1999 0.000 0.0 2000 0.000 0.0 2001 0.000 0.0 2002 0.000 0.0 2003 0.000 0.0 2004 0.000 0.0 2005 0.000 0.0 2006 0.000 0.0 2007 0.000 0.0 2008 0.000 0.0 2009 0.000 0.0 2010 0.000 0.0 2011 0.000 0.0 2012 0.000 0.0 2013 0.000 0.0 2014 0.000 0.0 2015 0.000 0.0 2016 0.000 0.0 2017 0.000 0.0 2018 0.000 0.0 2019 0.000 0.0 2020 0.000 0.0 2021 0.000 0.0 2022 0.000 0.0 2023 0.000 0.0 2024 0.000 0.0 2025 0.000 0.0 2026 0.000 0.0 2027 0.000 0.0 Page 29 of 31 2028 0.000 0.0 2029 0.000 0.0 2030 0.000 0.0 2031 0.000 0.0 2032 0.000 0.0 2033 0.000 0.0 2034 0.000 0.0 2035 0.000 0.0 2036 0.000 0.0 2037 0.000 0.0 2038 0.000 0.0 2039 0.000 0.0 2040 0.000 0.0 2041 0.000 0.0 2042 0.000 0.0 2043 0.000 0.0 2044 0.000 0.0 2045 0.000 0.0 2046 0.000 0.0 2047 0.000 0.0 2048 0.000 0.0 2049 0.000 0.0 2050 0.000 0.0 2051 0.000 0.0 2052 0.000 0.0 2053 0.000 0.0 2054 0.000 0.0 2055 0.000 0.0 2056 0.000 0.0 2057 0.000 0.0 2058 0.000 0.0 2059 0.000 0.0 2060 0.000 0.0 2061 0.000 0.0 2062 0.000 0.0 2063 0.000 0.0 2064 0.000 0.0 2065 0.000 0.0 2066 0.000 0.0 2067 0.000 0.0 2068 0.000 0.0 2069 0.000 0.0 2070 0.000 0.0 2071 0.000 0.0 2072 0.000 0.0 2073 0.000 0.0 2074 0.000 0.0 2075 0.000 0.0 2076 0.000 0.0 2077 0.000 0.0 2078 0.000 0.0 2079 0.000 0.0 2080 0.000 0.0 2081 0.000 0.0 2082 0.000 0.0 2083 0.000 0.0 Page 30 of 31 2084 0.000 0.0 2085 0.000 0.0 2086 0.000 0.0 2087 0.000 0.0 2088 0.000 0.0 2089 0.000 0.0 2090 0.000 0.0 2091 0.000 0.0 2092 0.000 0.0 2093 0.000 0.0 2094 0.000 0.0 2095 0.000 0.0 2096 0.000 0.0 2097 0.000 0.0 Page 31 of 31 Madrona School – Edmonds School District Appendix G Appendix G Stormwater Pollution Prevention (SWPP) · SWPP Report (partially completed, pending contractor selection) Construction Stormwater General Permit Stormwater Pollution Prevention Plan (SWPPP) for Madrona School Prepared for: The Washington State Department of Ecology Northwest Regional Office Permittee / Owner Developer Operator / Contractor Edmonds School District N/A TBD Edmonds, WA Update as necessary. Certified Erosion and Sediment Control Lead (CESCL) Name Organization Contact Phone Number TBD TBD TBD SWPPP Prepared By Name Organization Contact Phone Number Christopher Borzio, PE KPFF Consulting Engineers (206) 622-5822 SWPPP Preparation Date 12/04/2016 Project Construction Dates Activity / Phase Start Date End Date Site Work 5/1/2017 10/10/2018 P a g e | 1 Table of Contents 1 Project Information .............................................................................................................. 4 1.1 Existing Conditions ...................................................................................................... 4 1.2 Proposed Construction Activities .................................................................................. 5 2 Construction Stormwater Best Management Practices (BMPs) ........................................... 6 2.1 The 13 Elements .......................................................................................................... 6 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits ........................................ 6 2.1.2 Element 2: Establish Construction Access ............................................................ 7 2.1.3 Element 3: Control Flow Rates ............................................................................. 8 2.1.4 Element 4: Install Sediment Controls .................................................................... 9 2.1.5 Element 5: Stabilize Soils ....................................................................................10 2.1.6 Element 6: Protect Slopes....................................................................................10 2.1.7 Element 7: Protect Drain Inlets ............................................................................11 2.1.8 Element 8: Stabilize Channels and Outlets ..........................................................12 2.1.9 Element 9: Control Pollutants ...............................................................................13 2.1.10 Element 10: Control Dewatering ..........................................................................15 2.1.11 Element 11: Maintain BMPs .................................................................................16 2.1.12 Element 12: Manage the Project ..........................................................................17 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs .................................19 3 Pollution Prevention Team .................................................................................................21 4 Monitoring and Sampling Requirements ............................................................................22 4.1 Site Inspection ............................................................................................................22 4.2 Stormwater Quality Sampling ......................................................................................22 4.2.1 Turbidity Sampling ...............................................................................................22 4.2.2 pH Sampling ........................................................................................................24 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies .........................25 5.1 303(d) Listed Waterbodies ..........................................................................................25 5.2 TMDL Waterbodies .....................................................................................................25 6 Reporting and Record Keeping ..........................................................................................26 6.1 Record Keeping ..........................................................................................................26 6.1.1 Site Log Book ......................................................................................................26 6.1.2 Records Retention ...............................................................................................26 6.1.3 Updating the SWPPP ...........................................................................................26 6.2 Reporting ....................................................................................................................27 6.2.1 Discharge Monitoring Reports ..............................................................................27 6.2.2 Notification of Noncompliance ..............................................................................27 P a g e | 2 List of Tables Table 1 – Summary of Site Pollutant Constituents ..................................................................... 4 Table 2 – Pollutants ..................................................................................................................13 Table 3 – pH-Modifying Sources ...............................................................................................13 Table 4 – Dewatering BMPs ......................................................................................................15 Table 5 – Management .............................................................................................................17 Table 6 – BMP Implementation Schedule .................................................................................18 Table 7 – Team Information ......................................................................................................21 Table 8 – Turbidity Sampling Method ........................................................................................22 Table 9 – pH Sampling Method .................................................................................................24 List of Appendices Appendix/Glossary A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations P a g e | 3 List of Acronyms and Abbreviations Acronym / Abbreviation Explanation 303(d) Section of the Clean Water Act pertaining to Impaired Waterbodies BFO Bellingham Field Office of the Department of Ecology BMP(s) Best Management Practice(s) CESCL Certified Erosion and Sediment Control Lead CO2 Carbon Dioxide CRO Central Regional Office of the Department of Ecology CSWGP Construction Stormwater General Permit CWA Clean Water Act DMR Discharge Monitoring Report DO Dissolved Oxygen Ecology Washington State Department of Ecology EPA United States Environmental Protection Agency ERO Eastern Regional Office of the Department of Ecology ERTS Environmental Report Tracking System ESC Erosion and Sediment Control GULD General Use Level Designation NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Units NWRO Northwest Regional Office of the Department of Ecology pH Power of Hydrogen RCW Revised Code of Washington SPCC Spill Prevention, Control, and Countermeasure su Standard Units SWMMEW Stormwater Management Manual for Eastern Washington SWMMWW Stormwater Management Manual for Western Washington SWPPP Stormwater Pollution Prevention Plan TESC Temporary Erosion and Sediment Control SWRO Southwest Regional Office of the Department of Ecology TMDL Total Maximum Daily Load VFO Vancouver Field Office of the Department of Ecology WAC Washington Administrative Code WSDOT Washington Department of Transportation WWHM Western Washington Hydrology Model P a g e | 4 1 Project Information Project/Site Name: Madrona School Street/Location: 9300 236th St SW City: Edmonds State: WA Zip code: 98020 Subdivision: N/A Receiving waterbody: Edmonds Way Watershed – Puget Sound 1.1 Existing Conditions Total acreage (including support activities such as off-site equipment staging yards, material storage areas, borrow areas). Total acreage: 40 AC Disturbed acreage: 15 AC Existing structures: 2.9 AC Landscape topography: 6.4 AC (proposed) Drainage patterns: TDA #1 to 236th St SW, TDA 2 to the eastern wetland, TDA 3 to the western steep slope. See Appendix A. Existing Vegetation: Lawn, planters, and forest. Critical Areas (wetlands, streams, high erosion risk, steep or difficult to stabilize slopes): Wetland and steep slope east of site and steep slope west of site. List of known impairments for 303(d) listed or Total Maximum Daily Load (TMDL) for the receiving waterbody: According to the Washington State Water Quality Atlas website, the Puget Sound is 303(d) listed for the following pollutants at the Edmonds Way outfall: Bacteria, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Chrysene, and Polychlorinated Biphenyls (PCBs). Table 1 includes a list of suspected and/or known contaminants associated with the construction activity. Table 1 – Summary of Site Pollutant Constituents Constituent (Pollutant) Location Depth Concentration Various Hazardous Building Materials Existing Buildings to be demolished See 2015 RBM Assessment Report See 2015 RBM Assessment Report P a g e | 5 1.2 Proposed Construction Activities The existing Madrona Elementary School will be demolished and replaced with a new school. The proposed school consists of a larger gymnasium and administration unit and five smaller classroom units. Other site improvements include new sports fields, play equipment, a bus drop-off loop, and parking lots. The new school will be situated in the field south of the existing school to enable phased construction while the existing school is in session. Construction Activities include, clearing and grading, landscaping, utility installation, paving, and building construction. The existing site is part of the larger Edmonds Way Watershed as defined on figure B – 1 in the Edmonds Supplement. The site is comprised of three Threshold Discharge Areas (TDA). TDA 1 includes the eastern half of 236th st and adjacent forested area as well as the eastern half of the staff parking lot and east driveway. TDA 1 drains through catch basins and pipes to the piped system in 236th St SW heading East to Edmonds Way. TDA 2 includes the eastern half of the site including half of the existing school, the southeastern field, and the large wetland. Some offsite area from the neighboring residences also is included in TDA 2. Surface runoff either sheet flows directly to the wetland or is discharged via open pipe ends or dispersion trenches. Runoff in the wetland pools at the south end against the 240th St SW embankment until reaching the 18” culvert crossing the road. Downstream of the culvert, runoff is directed to the Edmonds Way system via open ditches and pipes. TDA 3 includes the western half of the site including the remaining half of 236th st and the existing school, parent parking lot, track, and south western field. TDA 3 either sheet flows or discharges via open pipe ends or dispersion trenches to the steep slope west of the site. Edmonds School District Maintenance staff has noted that during heavy rain, flowing water originating from the steep slope encroaches on the former Woodway Elementary school. The site will be fully stabilized in the final condition through paving, landscaping, seeding, and building construction. There is no evidence to suggest that there are any existing contaminated soils or groundwater onsite. P a g e | 6 2 Construction Stormwater Best Management Practices (BMPs) The SWPPP is a living document reflecting current conditions and changes throughout the life of the project. These changes may be informal (i.e., hand-written notes and deletions). Update the SWPPP when the CESCL has noted a deficiency in BMPs or deviation from original design. 2.1 The 13 Elements 2.1.1 Element 1: Preserve Vegetation / Mark Clearing Limits Prior to earthmoving activities, the clearing limits will be staked and marked to ensure protection of native vegetation. List and describe BMPs: C101, C102, C103 Installation Schedules: Prior to earthmoving. Inspection and Maintenance plan: See Appendix B. Responsible Staff: TBD P a g e | 7 2.1.2 Element 2: Establish Construction Access Construction access shall be stabilized by maintaining existing asphalt drives, paving new asphalt treated base construction access routes, or by providing new stabilized construction entrances. Dust shall be kept to a minimum by watering and temporary site stabilization. All sediment tracked offsite by construction activity shall be swept immediately. Flushing sediment from city streets into the storm drainage system is not acceptable. List and describe BMPs: C105, C107, C140 Installation Schedules: Prior to earthmoving activity and maintained throughout construction. Inspection and Maintenance plan: See Appendix B. Responsible Staff: TBD P a g e | 8 2.1.3 Element 3: Control Flow Rates Flow rates shall be controlled using temporary portable sedimentation tanks discharging to existing outfalls. The permanent flow control facilities (Underground Injection Control Wells) shall not be used to control any construction phase runoff in order to protect the infiltrative capacity of the soil. All runoff prior to final site stabilization shall be directed to existing outfalls. Will you construct stormwater retention and/or detention facilities? Yes No Will you use permanent infiltration ponds or other low impact development (example: rain gardens, bio-retention, porous pavement) to control flow during construction? Yes No List and describe BMPs: Temporary Portable Sedimentation Tanks Installation Schedules: Prior to earthmoving activity. Inspection and Maintenance plan: Wet Season: Weekly and after heavy rainfall, Dry Season: Monthly and after rainfall. Responsible Staff: TBD P a g e | 9 2.1.4 Element 4: Install Sediment Controls BMPs, including silt fence, interceptor swales, straw wattles, check dams, catch basin protection, and Temporary Portable Sedimentation Tanks will minimize sediment discharge from the site. Each phase of construction activity shall utilize these BMPs to direct all site runoff to collection points where runoff can be pumped into the sedimentation tanks prior to discharge to existing outfalls. These elements will be upgraded if necessary to account for site conditions and rainfall. List and describe BMPs: C200, C201, C202, C207, C208, C209, C220, C233, C235. Installation Schedules: Prior to earthmoving activity and maintained throughout construction. Inspection and Maintenance plan: Wet Season: Weekly and after heavy rainfall, Dry Season: Monthly and after rainfall. See Appendix B. Responsible Staff: TBD P a g e | 10 2.1.5 Element 5: Stabilize Soils Exposed soil will be stabilized using a combination of temporary and semi permanent BMPs including erosion control nets, plastic covering, early top soiling, and if necessary Polyacrylamide soil stabilization. West of the Cascade Mountains Crest Season Dates Number of Days Soils Can be Left Exposed During the Dry Season May 1 – September 30 7 days During the Wet Season October 1 – April 30 2 days Soils must be stabilized at the end of the shift before a holiday or weekend if needed based on the weather forecast. Anticipated project dates: Start date: 5/1/2017 End date: 10/10/2018 Will you construct during the wet season? Yes No List and describe BMPs: C122, C123, C125, C126, C130, Installation Schedules: During earthmoving activity and maintained throughout construction. Inspection and Maintenance plan: Wet Season: Weekly and after heavy rainfall, Dry Season: Monthly and after rainfall. See Appendix B. Responsible Staff: TBD 2.1.6 Element 6: Protect Slopes All runoff will be directed away from proposed slopes onsite and these slopes will be covered during construction with plastic or erosion control netting. Existing steep slopes to the east and west of the site will not be disturbed aside from outfall construction and stabilization. All construction discharge to the western steep slope will be through existing stabilized outfalls. Stockpile slopes will be covered with plastic while unused. Will steep slopes be present at the site during construction? Yes No List and describe BMPs: C122, C123 Installation Schedules: During earthmoving activity and maintained throughout construction. P a g e | 11 Inspection and Maintenance plan: Wet Season: Weekly and after heavy rainfall, Dry Season: Monthly and after rainfall. See Appendix B Responsible Staff: TBD 2.1.7 Element 7: Protect Drain Inlets Storm drain inlets will be protected primarily by the onsite sediment control BMPs. All inlets onsite and in the vicinity of the site will be protected with catch basin inserts. List and describe BMPs: C220 Installation Schedules: Prior to earthmoving activity. Inspection and Maintenance plan: Wet Season: Weekly and daily during rainfall, Dry Season: Monthly and daily during rainfall. See Appendix B. Responsible Staff: TBD P a g e | 12 2.1.8 Element 8: Stabilize Channels and Outlets Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches, will be installed at the outlets of all conveyance systems. All proposed and temporary outlets will be inspected and upgraded where necessary to suit the phase of construction and weather conditions. Final outlet stabilization will be according to the site civil construction plans. Onsite permanent and temporary channels will be lined until fully stabilized. List and describe BMPs: C122, C209 Installation Schedules: Prior to earthmoving activity and maintained throughout construction Inspection and Maintenance plan: Wet Season: Weekly and after heavy rainfall, Dry Season: Monthly and after rainfall. See Appendix B. Responsible Staff: TBD P a g e | 13 2.1.9 Element 9: Control Pollutants The following pollutants are anticipated to be present on-site: Table 2 – Pollutants Pollutant (List pollutants and source, if applicable) Concrete dust and slurry (Building Demolition and onsite concrete work) Various Hazardous Building Materials (Existing Buildings to be demolished) Slurry generated from concrete sawcutting will be collected separately and disposed of legally. Concrete trucks will be cleaned only in designated concrete washout areas. Building demolition debris will be covered in plastic while onsite and disposed of legally. See the See 2015 RBM Assessment Report for hazardous materials specific to the existing buildings. List and describe BMPs: C151, C152, C153 Installation Schedules: During demolition and concrete work. Inspection and Maintenance plan: Daily during demolition and concrete work. Responsible Staff: TBD Will maintenance, fueling, and/or repair of heavy equipment and vehicles occur on-site? Yes No Will wheel wash or tire bath system BMPs be used during construction? Yes No Will pH-modifying sources be present on-site? Yes No Table 3 – pH-Modifying Sources None Bulk cement Cement kiln dust Fly ash Other cementitious materials New concrete washing or curing waters Waste streams generated from concrete grinding and sawing Exposed aggregate processes Dewatering concrete vaults P a g e | 14 Concrete pumping and mixer washout waters Recycled concrete Recycled concrete stockpiles Other (i.e., calcium lignosulfate) [please describe: ] Concrete trucks must not be washed out onto the ground, or into storm drains, open ditches, streets, or streams. Excess concrete must not be dumped on-site, except in designated concrete washout areas with appropriate BMPs installed. Will uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters? Yes No P a g e | 15 2.1.10 Element 10: Control Dewatering Large scale dewatering is not anticipated for this site; however, small amounts of perched groundwater water may require dewatering from utility trenches or other excavation activity. Turbid dewatering effluent will be routed to onsite stormwater management BMPs and discharged to existing stormwater outfalls. Table 4 – Dewatering BMPs Infiltration Transport off-site in a vehicle (vacuum truck for legal disposal) Ecology-approved on-site chemical treatment or other suitable treatment technologies Sanitary or combined sewer discharge with local sewer district approval (last resort) Use of sedimentation bag with discharge to ditch or swale (small volumes of localized dewatering) List and describe BMPs: See other elements for onsite stormwater management BMPs. Installation Schedules: During trenching activity. Inspection and Maintenance plan: Daily during trenching activity. Responsible Staff: TBD. P a g e | 16 2.1.11 Element 11: Maintain BMPs All temporary and permanent Erosion and Sediment Control (ESC) BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Maintenance and repair shall be conducted in accordance with each particular BMP specification (see Volume II of the SWMMWW or Chapter 7 of the SWMMEW). Visual monitoring of all BMPs installed at the site will be conducted at least once every calendar week and within 24 hours of any stormwater or non-stormwater discharge from the site. If the site becomes inactive and is temporarily stabilized, the inspection frequency may be reduced to once every calendar month. All temporary ESC BMPs shall be removed within 30 days after final site stabilization is achieved or after the temporary BMPs are no longer needed. Trapped sediment shall be stabilized on-site or removed. Disturbed soil resulting from removal of either BMPs or vegetation shall be permanently stabilized. Additionally, protection must be provided for all BMPs installed for the permanent control of stormwater from sediment and compaction. BMPs that are to remain in place following completion of construction shall be examined and restored to full operating condition. If sediment enters these BMPs during construction, the sediment shall be removed and the facility shall be returned to conditions specified in the construction documents. P a g e | 17 2.1.12 Element 12: Manage the Project The project will be managed based on the following principles: · Projects will be phased to the maximum extent practicable and seasonal work limitations will be taken into account. · Inspection and monitoring: o Inspection, maintenance and repair of all BMPs will occur as needed to ensure performance of their intended function. o Site inspections and monitoring will be conducted in accordance with Special Condition S4 of the CSWGP. Sampling locations are indicated on the Site Map. Sampling station(s) are located in accordance with applicable requirements of the CSWGP. · Maintain an updated SWPPP. o The SWPPP will be updated, maintained, and implemented in accordance with Special Conditions S3, S4, and S9 of the CSWGP. As site work progresses the SWPPP will be modified routinely to reflect changing site conditions. The SWPPP will be reviewed monthly to ensure the content is current. Table 5 – Management Design the project to fit the existing topography, soils, and drainage patterns Emphasize erosion control rather than sediment control Minimize the extent and duration of the area exposed Keep runoff velocities low Retain sediment on-site Thoroughly monitor site and maintain all ESC measures Schedule major earthwork during the dry season Other (please describe) P a g e | 18 Table 6 – BMP Implementation Schedule Phase of Construction Project Stormwater BMPs Date Wet/Dry Season [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] Phase of Construction Project Stormwater BMPs Date Wet/Dry Season P a g e | 19 [Insert construction activity] [Insert BMP] [MM/DD/YYYY] [Insert Season] 2.1.13 Element 13: Protect Low Impact Development (LID) BMPs The site employs bioretention, underground injection control well, and permeable pavements. These facilities are especially sensitive to sedimentation. P a g e | 20 Prior to installation, bioretention areas will be staked, marked, and fenced to prevent compaction by heavy construction equipment. After installation, Bioretention areas will be protected from foot and construction traffic. The side slopes will be protected from concentrated flow to prevent erosion of the biofiltration media. The UIC wells will remain offline until the site has been fully stabilized in order to maintain their infiltrative capacity. Temporary sediment controls will remain until the UIC wells are brought online. Permeable pavements will be protected from sediment by careful scheduling and protection from construction traffic. Permeable pavements and permeable base material will be installed after the surrounding earthwork is complete. Permeable pavements that are fouled by sedimentation will be cleaned via water jetting vacuum truck. P a g e | 21 3 Pollution Prevention Team Table 7 – Team Information Title Name(s) Phone Number Certified Erosion and Sediment Control Lead (CESCL) TBD TBD Resident Engineer TBD TBD Emergency Ecology Contact TBD TBD Emergency Permittee/ Owner Contact TBD TBD Non-Emergency Owner Contact TBD TBD Monitoring Personnel TBD TBD Ecology Regional Office Northwest Regional Office 425-649-7000 P a g e | 22 4 Monitoring and Sampling Requirements Monitoring includes visual inspection, sampling for water quality parameters of concern, and documentation of the inspection and sampling findings in a site log book. A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Stormwater sampling data See Appendix D for inspection form. The site log book must be maintained on-site within reasonable access to the site and be made available upon request to Ecology or the local jurisdiction. Numeric effluent limits may be required for certain discharges to 303(d) listed waterbodies. See CSWGP Special Condition S8 and Section 5 of this template. 4.1 Site Inspection Site inspections will be conducted at least once every calendar week and within 24 hours following any discharge from the site. For sites that are temporarily stabilized and inactive, the required frequency is reduced to once per calendar month. The discharge point(s) are indicated on the Site Map (see Appendix A) and in accordance with the applicable requirements of the CSWGP. 4.2 Stormwater Quality Sampling 4.2.1 Turbidity Sampling Requirements include calibrated turbidity meter or transparency tube to sample site discharges for compliance with the CSWGP. Sampling will be conducted at all discharge points at least once per calendar week. Method for sampling turbidity: Table 8 – Turbidity Sampling Method Turbidity Meter/Turbidimeter (required for disturbances 5 acres or greater in size) Transparency Tube (option for disturbances less than 1 acre and up to 5 acres in size) The benchmark for turbidity value is 25 nephelometric turbidity units (NTU) and a transparency less than 33 centimeters. If the discharge’s turbidity is 26 to 249 NTU or the transparency is less than 33 cm but equal to or greater than 6 cm, the following steps will be conducted: 1. Review the SWPPP for compliance with Special Condition S9. Make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. P a g e | 23 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. 3. Document BMP implementation and maintenance in the site log book. If the turbidity exceeds 250 NTU or the transparency is 6 cm or less at any time, the following steps will be conducted: 1. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) within 24 hours. · Central Region (Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, Yakima): (509) 575-2490 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/CRO_nerts_online.html · Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/ERO_nerts_online.html · Northwest Region (King, Kitsap, Island, San Juan, Skagit, Snohomish, Whatcom): (425) 649-7000 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/NWRO_nerts_online.html · Southwest Region (Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, Wahkiakum,): (360) 407-6300 or http://www.ecy.wa.gov/programs/spills/forms/nerts_online/SWRO_nerts_online.html 2. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible. Address the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period 3. Document BMP implementation and maintenance in the site log book. 4. Continue to sample discharges daily until one of the following is true: · Turbidity is 25 NTU (or lower). · Transparency is 33 cm (or greater). · Compliance with the water quality limit for turbidity is achieved. o 1 - 5 NTU over background turbidity, if background is less than 50 NTU o 1% - 10% over background turbidity, if background is 50 NTU or greater · The discharge stops or is eliminated. P a g e | 24 4.2.2 pH Sampling pH monitoring is required for “Significant concrete work” (i.e., greater than 1000 cubic yards poured concrete over the life of the project). The use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD] or fly ash) also requires pH monitoring. For significant concrete work, pH sampling will start the first day concrete is poured and continue until it is cured, typically three (3) weeks after the last pour. For engineered soils and recycled concrete, pH sampling begins when engineered soils or recycled concrete are first exposed to precipitation and continues until the area is fully stabilized. If the measured pH is 8.5 or greater, the following measures will be taken: 1. Prevent high pH water from entering storm sewer systems or surface water. 2. Adjust or neutralize the high pH water to the range of 6.5 to 8.5 su using appropriate technology such as carbon dioxide (CO2) sparging (liquid or dry ice). 3. Written approval will be obtained from Ecology prior to the use of chemical treatment other than CO2 sparging or dry ice. Method for sampling pH: TBD Table 9 – pH Sampling Method pH meter pH test kit Wide range pH indicator paper P a g e | 25 5 Discharges to 303(d) or Total Maximum Daily Load (TMDL) Waterbodies 5.1 303(d) Listed Waterbodies Circle the applicable answer, if necessary: Is the receiving water 303(d) (Category 5) listed for turbidity, fine sediment, phosphorus, or pH? Yes No List the impairment(s): Bacteria, Benzo(a)anthracene, Benzo(a)pyrene, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Chrysene, and Polychlorinated Biphenyls (PCBs). 5.2 TMDL Waterbodies Waste Load Allocation for CWSGP discharges: N/A - Proposed construction activities do not increase the load of the listed pollutants. Discharges to TMDL receiving waterbodies will meet in-stream water quality criteria at the point of discharge. The Construction Stormwater General Permit Proposed New Discharge to an Impaired Water Body form is included in Appendix F. P a g e | 26 6 Reporting and Record Keeping 6.1 Record Keeping 6.1.1 Site Log Book A site log book will be maintained for all on-site construction activities and will include: · A record of the implementation of the SWPPP and other permit requirements · Site inspections · Sample logs 6.1.2 Records Retention Records will be retained during the life of the project and for a minimum of three (3) years following the termination of permit coverage in accordance with Special Condition S5.C of the CSWGP. Permit documentation to be retained on-site: · CSWGP · Permit Coverage Letter · SWPPP · Site Log Book Permit documentation will be provided within 14 days of receipt of a written request from Ecology. A copy of the SWPPP or access to the SWPPP will be provided to the public when requested in writing in accordance with Special Condition S5.G.2.b of the CSWGP. 6.1.3 Updating the SWPPP The SWPPP will be modified if: · Found ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. · There is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. The SWPPP will be modified within seven (7) days if inspection(s) or investigation(s) determine additional or modified BMPs are necessary for compliance. An updated timeline for BMP implementation will be prepared. P a g e | 27 6.2 Reporting 6.2.1 Discharge Monitoring Reports Cumulative soil disturbance is one (1) acre or larger; therefore, Discharge Monitoring Reports (DMRs) will be submitted to Ecology monthly. If there was no discharge during a given monitoring period the DMR will be submitted as required, reporting “No Discharge”. The DMR due date is fifteen (15) days following the end of each calendar month. DMRs will be reported online through Ecology’s WQWebDMR System. To sign up for WQWebDMR go to: http://www.ecy.wa.gov/programs/wq/permits/paris/webdmr.html 6.2.2 Notification of Noncompliance If any of the terms and conditions of the permit is not met, and the resulting noncompliance may cause a threat to human health or the environment, the following actions will be taken: 1. Ecology will be notified within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (Regional office numbers listed below). 2. Immediate action will be taken to prevent the discharge/pollution or otherwise stop or correct the noncompliance. If applicable, sampling and analysis of any noncompliance will be repeated immediately and the results submitted to Ecology within five (5) days of becoming aware of the violation. 3. A detailed written report describing the noncompliance will be submitted to Ecology within five (5) days, unless requested earlier by Ecology. Specific information to be included in the noncompliance report is found in Special Condition S5.F.3 of the CSWGP. Anytime turbidity sampling indicates turbidity is 250 NTUs or greater, or water transparency is 6 cm or less, the Ecology Regional office will be notified by phone within 24 hours of analysis as required by Special Condition S5.A of the CSWGP. · Central Region at (509) 575-2490 for Benton, Chelan, Douglas, Kittitas, Klickitat, Okanogan, or Yakima County · Eastern Region at (509) 329-3400 for Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, or Whitman County · Northwest Region at (425) 649-7000 for Island, King, Kitsap, San Juan, Skagit, Snohomish, or Whatcom County · Southwest Region at (360) 407-6300 for Clallam, Clark, Cowlitz, Grays Harbor, Jefferson, Lewis, Mason, Pacific, Pierce, Skamania, Thurston, or Wahkiakum Include the following information: P a g e | 28 1. Your name and / Phone number 2. Permit number 3. City / County of project 4. Sample results 5. Date / Time of call 6. Date / Time of sample 7. Project name In accordance with Special Condition S4.D.5.b of the CSWGP, the Ecology Regional office will be notified if chemical treatment other than CO2 sparging is planned for adjustment of high pH water. P a g e | 29 Appendix/Glossary A. Site Map B. BMP Detail C. Correspondence D. Site Inspection Form E. Construction Stormwater General Permit (CSWGP) F. 303(d) List Waterbodies / TMDL Waterbodies Information G. Contaminated Site Information H. Engineering Calculations Appendix A - Site Map Appendix B - BMP Detail 4.1 Source Control BMPs BMP C101: Preserving Natural Vegetation Purpose The purpose of preserving natural vegetation is to reduce erosion wherever practicable. Limiting site disturbance is the single most effective method for reducing erosion. For example, conifers can hold up to about 50 percent of all rain that falls during a storm. Up to 20-30 percent of this rain may never reach the ground but is taken up by the tree or evaporates. Another benefit is that the rain held in the tree can be released slowly to the ground after the storm. Conditions of Use • Natural vegetation should be preserved on steep slopes, near perennial and intermittent watercourses or swales, and on building sites in wooded areas. • As required by local governments. Design and Installation Specifications Natural vegetation can be preserved in natural clumps or as individual trees, shrubs and vines. The preservation of individual plants is more difficult because heavy equipment is generally used to remove unwanted vegetation. The points to remember when attempting to save individual plants are: • Is the plant worth saving? Consider the location, species, size, age, vigor, and the work involved. Local governments may also have ordinances to save natural vegetation and trees. • Fence or clearly mark areas around trees that are to be saved. It is preferable to keep ground disturbance away from the trees at least as far out as the dripline. Plants need protection from three kinds of injuries: • Construction Equipment - This injury can be above or below the ground level. Damage results from scarring, cutting of roots, and compaction of the soil. Placing a fenced buffer zone around plants to be saved prior to construction can prevent construction equipment injuries. • Grade Changes - Changing the natural ground level will alter grades, which affects the plant's ability to obtain the necessary air, water, and minerals. Minor fills usually do not cause problems although sensitivity between species does vary and should be checked. Trees can tolerate fill of 6 inches or less. For shrubs and other plants, the fill should be less. When there are major changes in grade, it may become necessary to supply air to the roots of plants. This can be done by placing a layer of gravel and a tile system over the roots before the fill is made. A tile 4-2 Volume II – Construction Stormwater Pollution Prevention February 2005 system protects a tree from a raised grade. The tile system should be laid out on the original grade leading from a dry well around the tree trunk. The system should then be covered with small stones to allow air to circulate over the root area. Lowering the natural ground level can seriously damage trees and shrubs. The highest percentage of the plant roots are in the upper 12 inches of the soil and cuts of only 2-3 inches can cause serious injury. To protect the roots it may be necessary to terrace the immediate area around the plants to be saved. If roots are exposed, construction of retaining walls may be needed to keep the soil in place. Plants can also be preserved by leaving them on an undisturbed, gently sloping mound. To increase the chances for survival, it is best to limit grade changes and other soil disturbances to areas outside the dripline of the plant. • Excavations - Protect trees and other plants when excavating for drainfields, power, water, and sewer lines. Where possible, the trenches should be routed around trees and large shrubs. When this is not possible, it is best to tunnel under them. This can be done with hand tools or with power augers. If it is not possible to route the trench around plants to be saved, then the following should be observed: Cut as few roots as possible. When you have to cut, cut clean. Paint cut root ends with a wood dressing like asphalt base paint. Backfill the trench as soon as possible. Tunnel beneath root systems as close to the center of the main trunk to preserve most of the important feeder roots. Some problems that can be encountered with a few specific trees are: • Maple, Dogwood, Red alder, Western hemlock, Western red cedar, and Douglas fir do not readily adjust to changes in environment and special care should be taken to protect these trees. • The windthrow hazard of Pacific silver fir and madronna is high, while that of Western hemlock is moderate. The danger of windthrow increases where dense stands have been thinned. Other species (unless they are on shallow, wet soils less than 20 inches deep) have a low windthrow hazard. • Cottonwoods, maples, and willows have water-seeking roots. These can cause trouble in sewer lines and infiltration fields. On the other hand, they thrive in high moisture conditions that other trees would not. • Thinning operations in pure or mixed stands of Grand fir, Pacific silver fir, Noble fir, Sitka spruce, Western red cedar, Western hemlock, February 2005 Volume II – Construction Stormwater Pollution Prevention 4-3 Pacific dogwood, and Red alder can cause serious disease problems. Disease can become established through damaged limbs, trunks, roots, and freshly cut stumps. Diseased and weakened trees are also susceptible to insect attack. Maintenance Standards • Inspect flagged and/or fenced areas regularly to make sure flagging or fencing has not been removed or damaged. If the flagging or fencing has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. • If tree roots have been exposed or injured, “prune” cleanly with an appropriate pruning saw or lopers directly above the damaged roots and recover with native soils. Treatment of sap flowing trees (fir, hemlock, pine, soft maples) is not advised as sap forms a natural healing barrier. 4-4 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C102: Buffer Zones Purpose An undisturbed area or strip of natural vegetation or an established suitable planting that will provide a living filter to reduce soil erosion and runoff velocities. Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of water that need protection from erosion and sedimentation. Vegetative buffer zones can be used to protect natural swales and can be incorporated into the natural landscaping of an area. Critical-areas buffer zones should not be used as sediment treatment areas. These areas shall remain completely undisturbed. The local permitting authority may expand the buffer widths temporarily to allow the use of the expanded area for removal of sediment. Design and Installation Specifications • Preserving natural vegetation or plantings in clumps, blocks, or strips is generally the easiest and most successful method. • Leave all unstable steep slopes in natural vegetation. • Mark clearing limits and keep all equipment and construction debris out of the natural areas. Steel construction fencing is the most effective method in protecting sensitive areas and buffers. Alternatively, wire-backed silt fence on steel posts is marginally effective. Flagging alone is typically not effective. • Keep all excavations outside the dripline of trees and shrubs. • Do not push debris or extra soil into the buffer zone area because it will cause damage from burying and smothering. • Vegetative buffer zones for streams, lakes or other waterways shall be established by the local permitting authority or other state or federal permits or approvals. Maintenance Standards • Inspect the area frequently to make sure flagging remains in place and the area remains undisturbed. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-5 BMP C103: High Visibility Plastic or Metal Fence Purpose Fencing is intended to: (1) restrict clearing to approved limits; (2) prevent disturbance of sensitive areas, their buffers, and other areas required to be left undisturbed; (3) limit construction traffic to designated construction entrances or roads; and, (4) protect areas where marking with survey tape may not provide adequate protection. Conditions of Use To establish clearing limits, plastic or metal fence may be used: • At the boundary of sensitive areas, their buffers, and other areas required to be left uncleared. • As necessary to control vehicle access to and on the site. Design and Installation Specifications • High visibility plastic fence shall be composed of a high-density polyethylene material and shall be at least four feet in height. Posts for the fencing shall be steel or wood and placed every 6 feet on center (maximum) or as needed to ensure rigidity. The fencing shall be fastened to the post every six inches with a polyethylene tie. On long continuous lengths of fencing, a tension wire or rope shall be used as a top stringer to prevent sagging between posts. The fence color shall be high visibility orange. The fence tensile strength shall be 360 lbs./ft. using the ASTM D4595 testing method. • Metal fences shall be designed and installed according to the manufacturer's specifications. • Metal fences shall be at least 3 feet high and must be highly visible. • Fences shall not be wired or stapled to trees. Maintenance Standards • If the fence has been damaged or visibility reduced, it shall be repaired or replaced immediately and visibility restored. 4-6 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C105: Stabilized Construction Entrance Purpose Construction entrances are stabilized to reduce the amount of sediment transported onto paved roads by vehicles or equipment by constructing a stabilized pad of quarry spalls at entrances to construction sites. Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving a construction site and traveling on paved roads or other paved areas within 1,000 feet of the site. On large commercial, highway, and road projects, the designer should include enough extra materials in the contract to allow for additional stabilized entrances not shown in the initial Construction SWPPP. It is difficult to determine exactly where access to these projects will take place; additional materials will enable the contractor to install them where needed. Design and Installation Specifications • See Figure 4.2 for details. Note: the 100’ minimum length of the entrance shall be reduced to the maximum practicable size when the size or configuration of the site does not allow the full length (100’). • A separation geotextile shall be placed under the spalls to prevent fine sediment from pumping up into the rock pad. The geotextile shall meet the following standards: Grab Tensile Strength (ASTM D4751) 200 psi min. Grab Tensile Elongation (ASTM D4632) 30% max. Mullen Burst Strength (ASTM D3786-80a) 400 psi min. AOS (ASTM D4751) 20-45 (U.S. standard sieve size) • Consider early installation of the first lift of asphalt in areas that will paved; this can be used as a stabilized entrance. Also consider the installation of excess concrete as a stabilized entrance. During large concrete pours, excess concrete is often available for this purpose. • Hog fuel (wood-based mulch) may be substituted for or combined with quarry spalls in areas that will not be used for permanent roads. Hog fuel is generally less effective at stabilizing construction entrances and should be used only at sites where the amount of traffic is very limited. Hog fuel is not recommended for entrance stabilization in urban areas. The effectiveness of hog fuel is highly variable and it generally requires more maintenance than quarry spalls. The inspector may at any time require the use of quarry spalls if the hog fuel is not preventing sediment from being tracked onto pavement or if the hog fuel is being carried onto pavement. Hog fuel is prohibited in permanent roadbeds because organics in the subgrade soils cause degradation of the subgrade support over time. • Fencing (see BMPs C103 and C104) shall be installed as necessary to restrict traffic to the construction entrance. 4-8 Volume II – Construction Stormwater Pollution Prevention February 2005 • Whenever possible, the entrance shall be constructed on a firm, compacted subgrade. This can substantially increase the effectiveness of the pad and reduce the need for maintenance. Maintenance Standards • Quarry spalls (or hog fuel) shall be added if the pad is no longer in accordance with the specifications. • If the entrance is not preventing sediment from being tracked onto pavement, then alternative measures to keep the streets free of sediment shall be used. This may include street sweeping, an increase in the dimensions of the entrance, or the installation of a wheel wash. • Any sediment that is tracked onto pavement shall be removed by shoveling or street sweeping. The sediment collected by sweeping shall be removed or stabilized on site. The pavement shall not be cleaned by washing down the street, except when sweeping is ineffective and there is a threat to public safety. If it is necessary to wash the streets, the construction of a small sump shall be considered. The sediment would then be washed into the sump where it can be controlled. • Any quarry spalls that are loosened from the pad, which end up on the roadway shall be removed immediately. • If vehicles are entering or exiting the site at points other than the construction entrance(s), fencing (see BMPs C103 and C104) shall be installed to control traffic. • Upon project completion and site stabilization, all construction accesses intended as permanent access for maintenance shall be permanently stabilized. Figure 4.2 – Stabilized Construction Entrance 1 5 ’ m i n . February 2005 Volume II – Construction Stormwater Pollution Prevention 4-9 BMP C107: Construction Road/Parking Area Stabilization Purpose Stabilizing subdivision roads, parking areas, and other onsite vehicle transportation routes immediately after grading reduces erosion caused by construction traffic or runoff. Conditions of Use • Roads or parking areas shall be stabilized wherever they are constructed, whether permanent or temporary, for use by construction traffic. • Fencing (see BMPs C103 and C104) shall be installed, if necessary, to limit the access of vehicles to only those roads and parking areas that are stabilized. Design and Installation Specifications • On areas that will receive asphalt as part of the project, install the first lift as soon as possible. • A 6-inch depth of 2- to 4-inch crushed rock, gravel base, or crushed surfacing base course shall be applied immediately after grading or utility installation. A 4-inch course of asphalt treated base (ATB) may also be used, or the road/parking area may be paved. It may also be possible to use cement or calcium chloride for soil stabilization. If cement or cement kiln dust is used for roadbase stabilization, pH monitoring and BMPs are necessary to evaluate and minimize the effects on stormwater. If the area will not be used for permanent roads, parking areas, or structures, a 6-inch depth of hog fuel may also be used, but this is likely to require more maintenance. Whenever possible, construction roads and parking areas shall be placed on a firm, compacted subgrade. • Temporary road gradients shall not exceed 15 percent. Roadways shall be carefully graded to drain. Drainage ditches shall be provided on each side of the roadway in the case of a crowned section, or on one side in the case of a super-elevated section. Drainage ditches shall be directed to a sediment control BMP. • Rather than relying on ditches, it may also be possible to grade the road so that runoff sheet-flows into a heavily vegetated area with a well- developed topsoil. Landscaped areas are not adequate. If this area has at least 50 feet of vegetation, then it is generally preferable to use the vegetation to treat runoff, rather than a sediment pond or trap. The 50 feet shall not include wetlands. If runoff is allowed to sheetflow through adjacent vegetated areas, it is vital to design the roadways and parking areas so that no concentrated runoff is created. • Storm drain inlets shall be protected to prevent sediment-laden water entering the storm drain system (see BMP C220). Maintenance Standards • Inspect stabilized areas regularly, especially after large storm events. • Crushed rock, gravel base, hog fuel, etc. shall be added as required to maintain a stable driving surface and to stabilize any areas that have eroded. • Following construction, these areas shall be restored to pre-construction condition or better to prevent future erosion. 4-12 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C122: Nets and Blankets Purpose Erosion control nets and blankets are intended to prevent erosion and hold seed and mulch in place on steep slopes and in channels so that vegetation can become well established. In addition, some nets and blankets can be used to permanently reinforce turf to protect drainage ways during high flows. Nets (commonly called matting) are strands of material woven into an open, but high-tensile strength net (for example, coconut fiber matting). Blankets are strands of material that are not tightly woven, but instead form a layer of interlocking fibers, typically held together by a biodegradable or photodegradable netting (for example, excelsior or straw blankets). They generally have lower tensile strength than nets, but cover the ground more completely. Coir (coconut fiber) fabric comes as both nets and blankets. Conditions of Use Erosion control nets and blankets should be used: • To aid permanent vegetated stabilization of slopes 2H:1V or greater and with more than 10 feet of vertical relief. • For drainage ditches and swales (highly recommended). The application of appropriate netting or blanket to drainage ditches and swales can protect bare soil from channelized runoff while vegetation is established. Nets and blankets also can capture a great deal of sediment due to their open, porous structure. Synthetic nets and blankets can be used to permanently stabilize channels and may provide a cost-effective, environmentally preferable alternative to riprap. 100 percent synthetic blankets manufactured for use in ditches may be easily reused as temporary ditch liners. Disadvantages of blankets include: • Surface preparation required; • On slopes steeper than 2.5:1, blanket installers may need to be roped and harnessed for safety; • They cost at least $4,000-6,000 per acre installed. Advantages of blankets include: • Can be installed without mobilizing special equipment; • Can be installed by anyone with minimal training; • Can be installed in stages or phases as the project progresses; • Seed and fertilizer can be hand-placed by the installers as they progress down the slope; • Can be installed in any weather; • There are numerous types of blankets that can be designed with various parameters in mind. Those parameters include: fiber blend, mesh strength, longevity, biodegradability, cost, and availability. 4-22 Volume II – Construction Stormwater Pollution Prevention February 2005 Design and Installation Specifications • See Figure 4.4 and Figure 4.5 for typical orientation and installation of blankets used in channels and as slope protection. Note: these are typical only; all blankets must be installed per manufacturer’s installation instructions. • Installation is critical to the effectiveness of these products. If good ground contact is not achieved, runoff can concentrate under the product, resulting in significant erosion. • Installation of Blankets on Slopes: 1. Complete final grade and track walk up and down the slope. 2. Install hydromulch with seed and fertilizer. 3. Dig a small trench, approximately 12 inches wide by 6 inches deep along the top of the slope. 4. Install the leading edge of the blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal,”U”-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. 5. Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer’s legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to maintain soil contact. In addition, no one is allowed to walk on the blanket after it is in place. 6. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket should overlap the leading edge of the lower blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. • With the variety of products available, it is impossible to cover all the details of appropriate use and installation. Therefore, it is critical that the design engineer consults the manufacturer's information and that a site visit takes place in order to insure that the product specified is appropriate. Information is also available at the following web sites: 1. WSDOT: http://www.wsdot.wa.gov/eesc/environmental/ 2. Texas Transportation Institute: http://www.dot.state.tx.us/insdtdot/orgchart/cmd/erosion/contents. htm February 2005 Volume II – Construction Stormwater Pollution Prevention 4-23 • Jute matting must be used in conjunction with mulch (BMP C121). Excelsior, woven straw blankets and coir (coconut fiber) blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. • In general, most nets (e.g., jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. • Extremely steep, unstable, wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks, beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. • 100 percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or fiber mesh and stitching which may last up to a year. • Most netting used with blankets is photodegradable, meaning they break down under sunlight (not UV stabilized). However, this process can take months or years even under bright sun. Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non-degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition, birds and small animals can become trapped in the netting. Maintenance Standards • Good contact with the ground must be maintained, and erosion must not occur beneath the net or blanket. • Any areas of the net or blanket that are damaged or not in close contact with the ground shall be repaired and stapled. • If erosion occurs due to poorly controlled drainage, the problem shall be fixed and the eroded area protected. 4-24 Volume II – Construction Stormwater Pollution Prevention February 2005 Min. 2“Overlap Slope surface shall be smooth before placement for proper soil contact. Stapling pattern as per manufacturer ’s recommendations. Do not stretch blankets/mattings tight - allow the rolls t o mold to any irregularities. For slopes less than 3H:1V, rolls may be placed in horizontal strips. If there is a berm at the top of slope, anchor upslope of the berm. Anchor in 6"x6" min. Trench and staple at 12" intervals. Min. 6" overlap. Staple overlaps max. 5" spacing. Bring material down to a level area, turn the end under 4" and st aple at 12" intervals. Lime, fertilize, and seed before installation. Planting of shrubs, trees, etc. Should occur after installation. Figure 4.4 – Channel Installation Figure 4.4 – Channel Installation February 2005 Volume II – Construction Stormwater Pollution Prevention 4-25 Min. 2“Overlap Slope surface shall be smooth before placement for proper soil contact. Stapling pattern as per manufacturer ’s recommendations. Do not stretch blankets/mattings tight - allow the rolls t o mold to any irregularities. For slopes less than 3H:1V, rolls may be placed in horizontal strips. If there is a berm at the top of slope, anchor upslope of the berm. Anchor in 6"x6" min. Trench and staple at 12" intervals. Min. 6" overlap. Staple overlaps max. 5" spacing. Bring material down to a level area, turn the end under 4" and st aple at 12" intervals. Lime, fertilize, and seed before installation. Planting of shrubs, trees, etc. Should occur after installation. Figure 4.5 – Slope Installation February 2005 Volume II – Construction Stormwater Pollution Prevention 4-25 BMP C123: Plastic Covering Purpose Plastic covering provides immediate, short-term erosion protection to slopes and disturbed areas. Conditions of Use • Plastic covering may be used on disturbed areas that require cover measures for less than 30 days, except as stated below. • Plastic is particularly useful for protecting cut and fill slopes and stockpiles. Note: The relatively rapid breakdown of most polyethylene sheeting makes it unsuitable for long-term (greater than six months) applications. • Clear plastic sheeting can be used over newly-seeded areas to create a greenhouse effect and encourage grass growth if the hydroseed was installed too late in the season to establish 75 percent grass cover, or if the wet season started earlier than normal. Clear plastic should not be used for this purpose during the summer months because the resulting high temperatures can kill the grass. • Due to rapid runoff caused by plastic sheeting, this method shall not be used upslope of areas that might be adversely impacted by concentrated runoff. Such areas include steep and/or unstable slopes. • While plastic is inexpensive to purchase, the added cost of installation, maintenance, removal, and disposal make this an expensive material, up to $1.50-2.00 per square yard. • Whenever plastic is used to protect slopes, water collection measures must be installed at the base of the slope. These measures include plastic-covered berms, channels, and pipes used to covey clean rainwater away from bare soil and disturbed areas. At no time is clean runoff from a plastic covered slope to be mixed with dirty runoff from a project. • Other uses for plastic include: 1. Temporary ditch liner; 2. Pond liner in temporary sediment pond; 3. Liner for bermed temporary fuel storage area if plastic is not reactive to the type of fuel being stored; 4. Emergency slope protection during heavy rains; and, 5. Temporary drainpipe (“elephant trunk”) used to direct water. 4-26 Volume II – Construction Stormwater Pollution Prevention February 2005 Design and Installation Specifications • Plastic slope cover must be installed as follows: 1. Run plastic up and down slope, not across slope; 2. Plastic may be installed perpendicular to a slope if the slope length is less than 10 feet; 3. Minimum of 8-inch overlap at seams; 4. On long or wide slopes, or slopes subject to wind, all seams should be taped; 5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench at the top of the slope and backfill with soil to keep water from flowing underneath; 6. Place sand filled burlap or geotextile bags every 3 to 6 feet along seams and pound a wooden stake through each to hold them in place; 7. Inspect plastic for rips, tears, and open seams regularly and repair immediately. This prevents high velocity runoff from contacting bare soil which causes extreme erosion; 8. Sandbags may be lowered into place tied to ropes. However, all sandbags must be staked in place. • Plastic sheeting shall have a minimum thickness of 0.06 millimeters. • If erosion at the toe of a slope is likely, a gravel berm, riprap, or other suitable protection shall be installed at the toe of the slope in order to reduce the velocity of runoff. Maintenance Standards • Torn sheets must be replaced and open seams repaired. • If the plastic begins to deteriorate due to ultraviolet radiation, it must be completely removed and replaced. • When the plastic is no longer needed, it shall be completely removed. • Dispose of old tires appropriately. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-27 BMP C125: Topsoiling Purpose To provide a suitable growth medium for final site stabilization with vegetation. While not a permanent cover practice in itself, topsoiling is an integral component of providing permanent cover in those areas where there is an unsuitable soil surface for plant growth. Native soils and disturbed soils that have been organically amended not only retain much more stormwater, but they also serve as effective biofilters for urban pollutants and, by supporting more vigorous plant growth, reduce the water, fertilizer and pesticides needed to support installed landscapes. Topsoil does not include any subsoils but only the material from the top several inches including organic debris. Conditions of Use • Native soils should be left undisturbed to the maximum extent practicable. Native soils disturbed during clearing and grading should be restored, to the maximum extent practicable, to a condition where moisture-holding capacity is equal to or better than the original site conditions. This criterion can be met by using on-site native topsoil, incorporating amendments into on-site soil, or importing blended topsoil. • Topsoiling is a required procedure when establishing vegetation on shallow soils, and soils of critically low pH (high acid) levels. • Stripping of existing, properly functioning soil system and vegetation for the purpose of topsoiling during construction is not acceptable. If an existing soil system is functioning properly it shall be preserved in its undisturbed and uncompacted condition. • Depending on where the topsoil comes from, or what vegetation was on site before disturbance, invasive plant seeds may be included and could cause problems for establishing native plants, landscaped areas, or grasses. • Topsoil from the site will contain mycorrhizal bacteria that are necessary for healthy root growth and nutrient transfer. These native mycorrhiza are acclimated to the site and will provide optimum conditions for establishing grasses. Commercially available mycorrhiza products should be used when topsoil is brought in from off-site. Design and Installation Specifications If topsoiling is to be done, the following items should be considered: • Maximize the depth of the topsoil wherever possible to provide the maximum possible infiltration capacity and beneficial growth medium. Topsoil depth shall be at least 8 inches with a minimum organic content of 10 percent dry weight and pH between 6.0 and 8.0 or matching the pH of the undisturbed soil. This can be accomplished either by returning native topsoil to the site and/or incorporating organic amendments. Organic amendments should be incorporated to a minimum 8-inch depth except where tree roots or other natural February 2005 Volume II – Construction Stormwater Pollution Prevention 4-29 features limit the depth of incorporation. Subsoils below the 12-inch depth should be scarified at least 2 inches to avoid stratified layers, where feasible. The decision to either layer topsoil over a subgrade or incorporate topsoil into the underlying layer may vary depending on the planting specified. • If blended topsoil is imported, then fines should be limited to 25 percent passing through a 200 sieve. • The final composition and construction of the soil system will result in a natural selection or favoring of certain plant species over time. For example, recent practices have shown that incorporation of topsoil may favor grasses, while layering with mildly acidic, high-carbon amendments may favor more woody vegetation. • Locate the topsoil stockpile so that it meets specifications and does not interfere with work on the site. It may be possible to locate more than one pile in proximity to areas where topsoil will be used. • Allow sufficient time in scheduling for topsoil to be spread prior to seeding, sodding, or planting. • Care must be taken not to apply to subsoil if the two soils have contrasting textures. Sandy topsoil over clayey subsoil is a particularly poor combination, as water creeps along the junction between the soil layers and causes the topsoil to slough. • If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method to prevent a lack of bonding is to actually work the topsoil into the layer below for a depth of at least 6 inches. • Ripping or re-structuring the subgrade may also provide additional benefits regarding the overall infiltration and interflow dynamics of the soil system. • Field exploration of the site shall be made to determine if there is surface soil of sufficient quantity and quality to justify stripping. Topsoil shall be friable and loamy (loam, sandy loam, silt loam, sandy clay loam, clay loam). Areas of natural ground water recharge should be avoided. • Stripping shall be confined to the immediate construction area. A 4- to 6- inch stripping depth is common, but depth may vary depending on the particular soil. All surface runoff control structures shall be in place prior to stripping. Stockpiling of topsoil shall occur in the following manner: • Side slopes of the stockpile shall not exceed 2:1. • An interceptor dike with gravel outlet and silt fence shall surround all topsoil stockpiles between October 1 and April 30. Between May 1 4-30 Volume II – Construction Stormwater Pollution Prevention February 2005 and September 30, an interceptor dike with gravel outlet and silt fence shall be installed if the stockpile will remain in place for a longer period of time than active construction grading. • Erosion control seeding or covering with clear plastic or other mulching materials of stockpiles shall be completed within 2 days (October 1 through April 30) or 7 days (May 1 through September 30) of the formation of the stockpile. Native topsoil stockpiles shall not be covered with plastic. • Topsoil shall not be placed while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed sodding or seeding. • Previously established grades on the areas to be topsoiled shall be maintained according to the approved plan. • When native topsoil is to be stockpiled and reused the following should apply to ensure that the mycorrhizal bacterial, earthworms, and other beneficial organisms will not be destroyed: 1. Topsoil is to be re-installed within 4 to 6 weeks; 2. Topsoil is not to become saturated with water; 3. Plastic cover is not allowed. Maintenance Standards • Inspect stockpiles regularly, especially after large storm events. Stabilize any areas that have eroded. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-31 BMP C126: Polyacrylamide for Soil Erosion Protection Purpose Polyacrylamide (PAM) is used on construction sites to prevent soil erosion. Applying PAM to bare soil in advance of a rain event significantly reduces erosion and controls sediment in two ways. First, PAM increases the soil’s available pore volume, thus increasing infiltration through flocculation and reducing the quantity of stormwater runoff. Second, it increases flocculation of suspended particles and aids in their deposition, thus reducing stormwater runoff turbidity and improving water quality. Conditions of Use PAM shall not be directly applied to water or allowed to enter a water body. In areas that drain to a sediment pond, PAM can be applied to bare soil under the following conditions: • During rough grading operations. • Staging areas. • Balanced cut and fill earthwork. • Haul roads prior to placement of crushed rock surfacing. • Compacted soil roadbase. • Stockpiles. • After final grade and before paving or final seeding and planting. • Pit sites. • Sites having a winter shut down. In the case of winter shut down, or where soil will remain unworked for several months, PAM should be used together with mulch. Design and Installation Specifications PAM may be applied in dissolved form with water, or it may be applied in dry, granular or powdered form. The preferred application method is the dissolved form. PAM is to be applied at a maximum rate of 2/3 pound PAM per 1000 gallons water (80 mg/L) per 1 acre of bare soil. Table 4.8 can be used to determine the PAM and water application rate for a disturbed soil area. Higher concentrations of PAM do not provide any additional effectiveness. Table 4.8 PAM and Water Application Rates Disturbed Area (ac) PAM (lbs) Water (gal) 0.50 0.33 500 1.00 0.66 1,000 1.50 1.00 1,500 2.00 1.32 2,000 2.50 1.65 2,500 3.00 2.00 3,000 3.50 2.33 3,500 4.00 2.65 4,000 4.50 3.00 4,500 5.00 3.33 5,000 4-32 Volume II – Construction Stormwater Pollution Prevention February 2005 The Preferred Method: • Pre-measure the area where PAM is to be applied and calculate the amount of product and water necessary to provide coverage at the specified application rate (2/3 pound PAM/1000 gallons/acre). • PAM has infinite solubility in water, but dissolves very slowly. Dissolve pre-measured dry granular PAM with a known quantity of clean water in a bucket several hours or overnight. Mechanical mixing will help dissolve the PAM. Always add PAM to water - not water to PAM. • Pre-fill the water truck about 1/8 full with water. The water does not have to be potable, but it must have relatively low turbidity – in the range of 20 NTU or less. • Add PAM /Water mixture to the truck • Completely fill the water truck to specified volume. • Spray PAM/Water mixture onto dry soil until the soil surface is uniformly and completely wetted. An Alternate Method: PAM may also be applied as a powder at the rate of 5 lbs. per acre. This must be applied on a day that is dry. For areas less than 5-10 acres, a hand-held “organ grinder” fertilizer spreader set to the smallest setting will work. Tractor-mounted spreaders will work for larger areas. The following shall be used for application of PAM: • PAM shall be used in conjunction with other BMPs and not in place of other BMPs. • Do not use PAM on a slope that flows directly into a stream or wetland. The stormwater runoff shall pass through a sediment control BMP prior to discharging to surface waters. • Do not add PAM to water discharging from site. • When the total drainage area is greater than or equal to 5 acres, PAM treated areas shall drain to a sediment pond. • Areas less than 5 acres shall drain to sediment control BMPs, such as a minimum of 3 check dams per acre. The total number of check dams used shall be maximized to achieve the greatest amount of settlement of sediment prior to discharging from the site. Each check dam shall be spaced evenly in the drainage channel through which stormwater flows are discharged off-site. • On all sites, the use of silt fence shall be maximized to limit the discharges of sediment from the site. • All areas not being actively worked shall be covered and protected from rainfall. PAM shall not be the only cover BMP used. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-33 • PAM can be applied to wet soil, but dry soil is preferred due to less sediment loss. • PAM will work when applied to saturated soil but is not as effective as applications to dry or damp soil. • Keep the granular PAM supply out of the sun. Granular PAM loses its effectiveness in three months after exposure to sunlight and air. • Proper application and re-application plans are necessary to ensure total effectiveness of PAM usage. • PAM, combined with water, is very slippery and can be a safety hazard. Care must be taken to prevent spills of PAM powder onto paved surfaces. During an application of PAM, prevent over-spray from reaching pavement as pavement will become slippery. If PAM powder gets on skin or clothing, wipe it off with a rough towel rather than washing with water-this only makes cleanup messier and take longer. • Some PAMs are more toxic and carcinogenic than others. Only the most environmentally safe PAM products should be used. The specific PAM copolymer formulation must be anionic. Cationic PAM shall not be used in any application because of known aquatic toxicity problems. Only the highest drinking water grade PAM, certified for compliance with ANSI/NSF Standard 60 for drinking water treatment, will be used for soil applications. Recent media attention and high interest in PAM has resulted in some entrepreneurial exploitation of the term "polymer." All PAM are polymers, but not all polymers are PAM, and not all PAM products comply with ANSI/NSF Standard 60. PAM use shall be reviewed and approved by the local permitting authority. The Washington State Department of Transportation (WSDOT) has listed approved PAM products on their web page. • PAM designated for these uses should be "water soluble" or "linear" or "non-crosslinked". Cross-linked or water absorbent PAM, polymerized in highly acidic (pH<2) conditions, are used to maintain soil moisture content. • The PAM anionic charge density may vary from 2-30 percent; a value of 18 percent is typical. Studies conducted by the United States Department of Agriculture (USDA)/ARS demonstrated that soil stabilization was optimized by using very high molecular weight (12- 15 mg/mole), highly anionic (>20% hydrolysis) PAM. • PAM tackifiers are available and being used in place of guar and alpha plantago. Typically, PAM tackifiers should be used at a rate of no more than 0.5-1 lb. per 1000 gallons of water in a hydromulch machine. Some tackifier product instructions say to use at a rate of 3 – 4-34 Volume II – Construction Stormwater Pollution Prevention February 2005 5 lbs. per acre, which can be too much. In addition, pump problems can occur at higher rates due to increased viscosity. Maintenance Standards • PAM may be reapplied on actively worked areas after a 48-hour period. • Reapplication is not required unless PAM treated soil is disturbed or unless turbidity levels show the need for an additional application. If PAM treated soil is left undisturbed a reapplication may be necessary after two months. More PAM applications may be required for steep slopes, silty and clayey soils (USDA Classification Type "C" and "D" soils), long grades, and high precipitation areas. When PAM is applied first to bare soil and then covered with straw, a reapplication may not be necessary for several months. • Loss of sediment and PAM may be a basis for penalties per RCW 90.48.080. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-35 BMP C130: Surface Roughening Purpose Surface roughening aids in the establishment of vegetative cover, reduces runoff velocity, increases infiltration, and provides for sediment trapping through the provision of a rough soil surface. Horizontal depressions are created by operating a tiller or other suitable equipment on the contour or by leaving slopes in a roughened condition by not fine grading them. Conditions for Use • All slopes steeper than 3:1 and greater than 5 vertical feet require surface roughening. • Areas with grades steeper than 3:1 should be roughened to a depth of 2 to 4 inches prior to seeding. • Areas that will not be stabilized immediately may be roughened to reduce runoff velocity until seeding takes place. • Slopes with a stable rock face do not require roughening. • Slopes where mowing is planned should not be excessively roughened. Design and Installation Specifications There are different methods for achieving a roughened soil surface on a slope, and the selection of an appropriate method depends upon the type of slope. Roughening methods include stair-step grading, grooving, contour furrows, and tracking. See Figure 4.6 for tracking and contour furrows. Factors to be considered in choosing a method are slope steepness, mowing requirements, and whether the slope is formed by cutting or filling. • Disturbed areas that will not require mowing may be stair-step graded, grooved, or left rough after filling. • Stair-step grading is particularly appropriate in soils containing large amounts of soft rock. Each "step" catches material that sloughs from above, and provides a level site where vegetation can become established. Stairs should be wide enough to work with standard earth moving equipment. Stair steps must be on contour or gullies will form on the slope. • Areas that will be mowed (these areas should have slopes less steep than 3:1) may have small furrows left by disking, harrowing, raking, or seed-planting machinery operated on the contour. • Graded areas with slopes greater than 3:1 but less than 2:1 should be roughened before seeding. This can be accomplished in a variety of ways, including "track walking," or driving a crawler tractor up and down the slope, leaving a pattern of cleat imprints parallel to slope contours. • Tracking is done by operating equipment up and down the slope to leave horizontal depressions in the soil. Maintenance Standards • Areas that are graded in this manner should be seeded as quickly as possible. • Regular inspections should be made of the area. If rills appear, they should be re-graded and re-seeded immediately. 4-36 Volume II – Construction Stormwater Pollution Prevention February 2005 Figure 4.6 – Surface Roughening by Tracking and Contour Furrows February 2005 Volume II – Construction Stormwater Pollution Prevention 4-37 BMP C140: Dust Control Purpose Dust control prevents wind transport of dust from disturbed soil surfaces onto roadways, drainage ways, and surface waters. Conditions of Use • In areas (including roadways) subject to surface and air movement of dust where on-site and off-site impacts to roadways, drainage ways, or surface waters are likely. Design and Installation Specifications • Vegetate or mulch areas that will not receive vehicle traffic. In areas where planting, mulching, or paving is impractical, apply gravel or landscaping rock. • Limit dust generation by clearing only those areas where immediate activity will take place, leaving the remaining area(s) in the original condition, if stable. Maintain the original ground cover as long as practical. • Construct natural or artificial windbreaks or windscreens. These may be designed as enclosures for small dust sources. • Sprinkle the site with water until surface is wet. Repeat as needed. To prevent carryout of mud onto street, refer to Stabilized Construction Entrance (BMP C105). • Irrigation water can be used for dust control. Irrigation systems should be installed as a first step on sites where dust control is a concern. • Spray exposed soil areas with a dust palliative, following the manufacturer’s instructions and cautions regarding handling and application. Used oil is prohibited from use as a dust suppressant. Local governments may approve other dust palliatives such as calcium chloride or PAM. • PAM (BMP C126) added to water at a rate of 0.5 lbs. per 1,000 gallons of water per acre and applied from a water truck is more effective than water alone. This is due to the increased infiltration of water into the soil and reduced evaporation. In addition, small soil particles are bonded together and are not as easily transported by wind. Adding PAM may actually reduce the quantity of water needed for dust control, especially in eastern Washington. Since the wholesale cost of PAM is about $ 4.00 per pound, this is an extremely cost- effective dust control method. Techniques that can be used for unpaved roads and lots include: • Lower speed limits. High vehicle speed increases the amount of dust stirred up from unpaved roads and lots. • Upgrade the road surface strength by improving particle size, shape, and mineral types that make up the surface and base materials. 4-40 Volume II – Construction Stormwater Pollution Prevention February 2005 • Add surface gravel to reduce the source of dust emission. Limit the amount of fine particles (those smaller than .075 mm) to 10 to 20 percent. • Use geotextile fabrics to increase the strength of new roads or roads undergoing reconstruction. • Encourage the use of alternate, paved routes, if available. • Restrict use by tracked vehicles and heavy trucks to prevent damage to road surface and base. • Apply chemical dust suppressants using the admix method, blending the product with the top few inches of surface material. Suppressants may also be applied as surface treatments. • Pave unpaved permanent roads and other trafficked areas. • Use vacuum street sweepers. • Remove mud and other dirt promptly so it does not dry and then turn into dust. • Limit dust-causing work on windy days. • Contact your local Air Pollution Control Authority for guidance and training on other dust control measures. Compliance with the local Air Pollution Control Authority constitutes compliance with this BMP. Maintenance Standards Respray area as necessary to keep dust to a minimum. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-41 BMP C151: Concrete Handling Purpose Concrete work can generate process water and slurry that contain fine particles and high pH, both of which can violate water quality standards in the receiving water. This BMP is intended to minimize and eliminate concrete process water and slurry from entering waters of the state. Conditions of Use Any time concrete is used, these management practices shall be utilized. Concrete construction projects include, but are not limited to, the following: • Curbs • Sidewalks • Roads • Bridges • Foundations • Floors • Runways Design and Installation Specifications • Concrete truck chutes, pumps, and internals shall be washed out only into formed areas awaiting installation of concrete or asphalt. • Unused concrete remaining in the truck and pump shall be returned to the originating batch plant for recycling. • Hand tools including, but not limited to, screeds, shovels, rakes, floats, and trowels shall be washed off only into formed areas awaiting installation of concrete or asphalt. • Equipment that cannot be easily moved, such as concrete pavers, shall only be washed in areas that do not directly drain to natural or constructed stormwater conveyances. • Washdown from areas such as concrete aggregate driveways shall not drain directly to natural or constructed stormwater conveyances. • When no formed areas are available, washwater and leftover product shall be contained in a lined container. Contained concrete shall be disposed of in a manner that does not violate groundwater or surface water quality standards. Maintenance Standards Containers shall be checked for holes in the liner daily during concrete pours and repaired the same day. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-43 BMP C152: Sawcutting and Surfacing Pollution Prevention Purpose Sawcutting and surfacing operations generate slurry and process water that contains fine particles and high pH (concrete cutting), both of which can violate the water quality standards in the receiving water. This BMP is intended to minimize and eliminate process water and slurry from entering waters of the State. Conditions of Use Anytime sawcutting or surfacing operations take place, these management practices shall be utilized. Sawcutting and surfacing operations include, but are not limited to, the following: • Sawing • Coring • Grinding • Roughening • Hydro-demolition • Bridge and road surfacing Design and Installation Specifications • Slurry and cuttings shall be vacuumed during cutting and surfacing operations. • Slurry and cuttings shall not remain on permanent concrete or asphalt pavement overnight. • Slurry and cuttings shall not drain to any natural or constructed drainage conveyance. • Collected slurry and cuttings shall be disposed of in a manner that does not violate groundwater or surface water quality standards. • Process water that is generated during hydro-demolition, surface roughening or similar operations shall not drain to any natural or constructed drainage conveyance and shall be disposed of in a manner that does not violate groundwater or surface water quality standards. • Cleaning waste material and demolition debris shall be handled and disposed of in a manner that does not cause contamination of water. If the area is swept with a pick-up sweeper, the material must be hauled out of the area to an appropriate disposal site. Maintenance Standards Continually monitor operations to determine whether slurry, cuttings, or process water could enter waters of the state. If inspections show that a violation of water quality standards could occur, stop operations and immediately implement preventive measures such as berms, barriers, secondary containment, and vacuum trucks. 4-44 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C153: Material Delivery, Storage and Containment Purpose Prevent, reduce, or eliminate the discharge of pollutants from material delivery and storage to the stormwater system or watercourses by minimizing the storage of hazardous materials onsite, storing materials in a designated area, and installing secondary containment. Conditions of Use These procedures are suitable for use at all construction sites with delivery and storage of the following materials: • Petroleum products such as fuel, oil and grease • Soil stabilizers and binders (e.g. Polyacrylamide) • Fertilizers, pesticides and herbicides • Detergents • Asphalt and concrete compounds • Hazardous chemicals such as acids, lime, adhesives, paints, solvents and curing compounds • Any other material that may be detrimental if released to the environment Design and Installation Specifications The following steps should be taken to minimize risk: • Temporary storage area should be located away from vehicular traffic, near the construction entrance(s), and away from waterways or storm drains. • Material Safety Data Sheets (MSDS) should be supplied for all materials stored. Chemicals should be kept in their original labeled containers. • Hazardous material storage on-site should be minimized. • Hazardous materials should be handled as infrequently as possible. • During the wet weather season (Oct 1 – April 30), consider storing materials in a covered area. • Materials should be stored in secondary containments, such as earthen dike, horse trough, or even a children’s wading pool for non-reactive materials such as detergents, oil, grease, and paints. Small amounts of material may be secondarily contained in “bus boy” trays or concrete mixing trays. • Do not store chemicals, drums, or bagged materials directly on the ground. Place these items on a pallet and, when possible, in secondary containment. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-45 • If drums must be kept uncovered, store them at a slight angle to reduce ponding of rainwater on the lids to reduce corrosion. Domed plastic covers are inexpensive and snap to the top of drums, preventing water from collecting. Material Storage Areas and Secondary Containment Practices: • Liquids, petroleum products, and substances listed in 40 CFR Parts 110, 117, or 302 shall be stored in approved containers and drums and shall not be overfilled. Containers and drums shall be stored in temporary secondary containment facilities. • Temporary secondary containment facilities shall provide for a spill containment volume able to contain precipitation from a 25 year, 24 hour storm event, plus 10% of the total enclosed container volume of all containers, or 110% of the capacity of the largest container within its boundary, whichever is greater. • Secondary containment facilities shall be impervious to the materials stored therein for a minimum contact time of 72 hours. • Secondary containment facilities shall be maintained free of accumulated rainwater and spills. In the event of spills or leaks, accumulated rainwater and spills shall be collected and placed into drums. These liquids shall be handled as hazardous waste unless testing determines them to be non-hazardous. • Sufficient separation should be provided between stored containers to allow for spill cleanup and emergency response access. • During the wet weather season (Oct 1 – April 30), each secondary containment facility shall be covered during non-working days, prior to and during rain events. • Keep material storage areas clean, organized and equipped with an ample supply of appropriate spill clean-up material (spill kit). • The spill kit should include, at a minimum: • 1-Water Resistant Nylon Bag • 3-Oil Absorbent Socks 3”x 4’ • 2-Oil Absorbent Socks 3”x 10’ • 12-Oil Absorbent Pads 17”x19” • 1-Pair Splash Resistant Goggles • 3-Pair Nitrile Gloves • 10-Disposable Bags with Ties • Instructions 4-46 Volume II – Construction Stormwater Pollution Prevention February 2005 4.2 Runoff Conveyance and Treatment BMPs BMP C200: Interceptor Dike and Swale Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the top or base of a disturbed slope or along the perimeter of a disturbed construction area to convey stormwater. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the construction site. Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed to an erosion control facility which can safely convey the stormwater. • Locate upslope of a construction site to prevent runoff from entering disturbed area. • When placed horizontally across a disturbed slope, it reduces the amount and velocity of runoff flowing down the slope. • Locate downslope to collect runoff from a disturbed area and direct it to a sediment basin. Design and Installation Specifications • Dike and/or swale and channel must be stabilized with temporary or permanent vegetation or other channel protection during construction. • Channel requires a positive grade for drainage; steeper grades require channel protection and check dams. • Review construction for areas where overtopping may occur. • Can be used at top of new fill before vegetation is established. • May be used as a permanent diversion channel to carry the runoff. • Sub-basin tributary area should be one acre or less. • Design capacity for the peak flow from a 10-year, 24-hour storm, assuming a Type 1A rainfall distribution, for temporary facilities. Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model. For facilities that will also serve on a permanent basis, consult the local government’s drainage requirements. Interceptor dikes shall meet the following criteria: Top Width 2 feet minimum. Height 1.5 feet minimum on berm. Side Slope 2:1 or flatter. Grade Depends on topography, however, dike system minimum is 0.5%, maximum is 1%. Compaction Minimum of 90 percent ASTM D698 standard proctor. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-57 Horizontal Spacing of Interceptor Dikes: Average Slope Slope Percent Flowpath Length 20H:1V or less 3-5% 300 feet (10 to 20)H:1V 5-10% 200 feet (4 to 10)H:1V 10-25% 100 feet (2 to 4)H:1V 25-50% 50 feet Stabilization depends on velocity and reach Slopes <5% Seed and mulch applied within 5 days of dike construction (see BMP C121, Mulching). Slopes 5 - 40% Dependent on runoff velocities and dike materials. Stabilization should be done immediately using either sod or riprap or other measures to avoid erosion. • The upslope side of the dike shall provide positive drainage to the dike outlet. No erosion shall occur at the outlet. Provide energy dissipation measures as necessary. Sediment-laden runoff must be released through a sediment trapping facility. • Minimize construction traffic over temporary dikes. Use temporary cross culverts for channel crossing. Interceptor swales shall meet the following criteria: Bottom Width 2 feet minimum; the bottom shall be level. Depth 1-foot minimum. Side Slope 2:1 or flatter. Grade Maximum 5 percent, with positive drainage to a suitable outlet (such as a sediment pond). Stabilization Seed as per BMP C120, Temporary and Permanent Seeding, or BMP C202, Channel Lining, 12 inches thick of riprap pressed into the bank and extending at least 8 inches vertical from the bottom. • Inspect diversion dikes and interceptor swales once a week and after every rainfall. Immediately remove sediment from the flow area. • Damage caused by construction traffic or other activity must be repaired before the end of each working day. Check outlets and make timely repairs as needed to avoid gully formation. When the area below the temporary diversion dike is permanently stabilized, remove the dike and fill and stabilize the channel to blend with the natural surface. 4-58 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C201: Grass-Lined Channels Purpose To provide a channel with a vegetative lining for conveyance of runoff. See Figure 4.7 for typical grass-lined channels. Conditions of Use This practice applies to construction sites where concentrated runoff needs to be contained to prevent erosion or flooding. • When a vegetative lining can provide sufficient stability for the channel cross section and at lower velocities of water (normally dependent on grade). This means that the channel slopes are generally less than 5 percent and space is available for a relatively large cross section. • Typical uses include roadside ditches, channels at property boundaries, outlets for diversions, and other channels and drainage ditches in low areas. • Channels that will be vegetated should be installed before major earthwork and hydroseeded with a bonded fiber matrix (BFM). The vegetation should be well established (i.e., 75 percent cover) before water is allowed to flow in the ditch. With channels that will have high flows, erosion control blankets should be installed over the hydroseed. If vegetation cannot be established from seed before water is allowed in the ditch, sod should be installed in the bottom of the ditch in lieu of hydromulch and blankets. Design and Installation Specifications Locate the channel where it can conform to the topography and other features such as roads. • Locate them to use natural drainage systems to the greatest extent possible. • Avoid sharp changes in alignment or bends and changes in grade. • Do not reshape the landscape to fit the drainage channel. • The maximum design velocity shall be based on soil conditions, type of vegetation, and method of revegetation, but at no times shall velocity exceed 5 feet/second. The channel shall not be overtopped by the peak runoff from a 10-year, 24-hour storm, assuming a Type 1A rainfall distribution." Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an approved continuous runoff model to determine a flow rate which the channel must contain. • Where the grass-lined channel will also function as a permanent stormwater conveyance facility, consultant the drainage conveyance requirements of the local government with jurisdiction. • An established grass or vegetated lining is required before the channel can be used to convey stormwater, unless stabilized with nets or blankets. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-59 • If design velocity of a channel to be vegetated by seeding exceeds 2 ft/sec, a temporary channel liner is required. Geotextile or special mulch protection such as fiberglass roving or straw and netting provide stability until the vegetation is fully established. See Figure 4.9. • Check dams shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • If vegetation is established by sodding, the permissible velocity for established vegetation may be used and no temporary liner is needed. • Do not subject grass-lined channel to sedimentation from disturbed areas. Use sediment-trapping BMPs upstream of the channel. • V-shaped grass channels generally apply where the quantity of water is small, such as in short reaches along roadsides. The V-shaped cross section is least desirable because it is difficult to stabilize the bottom where velocities may be high. • Trapezoidal grass channels are used where runoff volumes are large and slope is low so that velocities are nonerosive to vegetated linings. (Note: it is difficult to construct small parabolic shaped channels.) • Subsurface drainage, or riprap channel bottoms, may be necessary on sites that are subject to prolonged wet conditions due to long duration flows or a high water table. • Provide outlet protection at culvert ends and at channel intersections. • Grass channels, at a minimum, should carry peak runoff for temporary construction drainage facilities from the 10-year, 24-hour storm without eroding. Where flood hazard exists, increase the capacity according to the potential damage. • Grassed channel side slopes generally are constructed 3:1 or flatter to aid in the establishment of vegetation and for maintenance. • Construct channels a minimum of 0.2 foot larger around the periphery to allow for soil bulking during seedbed preparations and sod buildup. Maintenance Standards During the establishment period, check grass-lined channels after every rainfall. • After grass is established, periodically check the channel; check it after every heavy rainfall event. Immediately make repairs. • It is particularly important to check the channel outlet and all road crossings for bank stability and evidence of piping or scour holes. • Remove all significant sediment accumulations to maintain the designed carrying capacity. Keep the grass in a healthy, vigorous condition at all times, since it is the primary erosion protection for the channel. 4-60 Volume II – Construction Stormwater Pollution Prevention February 2005 February 2005 Volume II – Construction Stormwater Pollution Prevention 4-61 Figure 4.8 – Typical Grass-Lined Channels 4-62 Volume II – Construction Stormwater Pollution Prevention February 2005 Figure 4.9 – Temporary Channel Liners Excavate Channel to Design Grade and Cross Section BMP C202: Channel Lining Purpose To protect erodible channels by providing a channel liner using either blankets or riprap. Conditions of Use When natural soils or vegetated stabilized soils in a channel are not adequate to prevent channel erosion. • When a permanent ditch or pipe system is to be installed and a temporary measure is needed. • In almost all cases, synthetic and organic coconut blankets are more effective than riprap for protecting channels from erosion. Blankets can be used with and without vegetation. Blanketed channels can be designed to handle any expected flow and longevity requirement. Some synthetic blankets have a predicted life span of 50 years or more, even in sunlight. • Other reasons why blankets are better than rock include the availability of blankets over rock. In many areas of the state, rock is not easily obtainable or is very expensive to haul to a site. Blankets can be delivered anywhere. Rock requires the use of dump trucks to haul and heavy equipment to place. Blankets usually only require laborers with hand tools, and sometimes a backhoe. • The Federal Highway Administration recommends not using flexible liners whenever the slope exceeds 10 percent or the shear stress exceeds 8 lbs/ft2. Design and Installation Specifications See BMP C122 for information on blankets. Since riprap is used where erosion potential is high, construction must be sequenced so that the riprap is put in place with the minimum possible delay. • Disturbance of areas where riprap is to be placed should be undertaken only when final preparation and placement of the riprap can follow immediately behind the initial disturbance. Where riprap is used for outlet protection, the riprap should be placed before or in conjunction with the construction of the pipe or channel so that it is in place when the pipe or channel begins to operate. • The designer, after determining the riprap size that will be stable under the flow conditions, shall consider that size to be a minimum size and then, based on riprap gradations actually available in the area, select the size or sizes that equal or exceed the minimum size. The possibility of drainage structure damage by children shall be considered in selecting a riprap size, especially if there is nearby water or a gully in which to toss the stones. • Stone for riprap shall consist of field stone or quarry stone of approximately rectangular shape. The stone shall be hard and angular and of such quality that it will not disintegrate on exposure to water or February 2005 Volume II – Construction Stormwater Pollution Prevention 4-63 weathering and it shall be suitable in all respects for the purpose intended. • Rubble concrete may be used provided it has a density of at least 150 pounds per cubic foot, and otherwise meets the requirement of this standard and specification. • A lining of engineering filter fabric (geotextile) shall be placed between the riprap and the underlying soil surface to prevent soil movement into or through the riprap. The geotextile should be keyed in at the top of the bank. • Filter fabric shall not be used on slopes greater than 1-1/2:1 as slippage may occur. It should be used in conjunction with a layer of coarse aggregate (granular filter blanket) when the riprap to be placed is 12 inches and larger. 4-64 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C207: Check Dams Purpose Construction of small dams across a swale or ditch reduces the velocity of concentrated flow and dissipates energy at the check dam. Conditions of Use Where temporary channels or permanent channels are not yet vegetated, channel lining is infeasible, and velocity checks are required. • Check dams may not be placed in streams unless approved by the State Department of Fish and Wildlife. Check dams may not be placed in wetlands without approval from a permitting agency. • Check dams shall not be placed below the expected backwater from any salmonid bearing water between October 1 and May 31 to ensure that there is no loss of high flow refuge habitat for overwintering juvenile salmonids and emergent salmonid fry. Design and Installation Specifications Whatever material is used, the dam should form a triangle when viewed from the side. This prevents undercutting as water flows over the face of the dam rather than falling directly onto the ditch bottom. Check dams in association with sumps work more effectively at slowing flow and retaining sediment than just a check dam alone. A deep sump should be provided immediately upstream of the check dam. • In some cases, if carefully located and designed, check dams can remain as permanent installations with very minor regrading. They may be left as either spillways, in which case accumulated sediment would be graded and seeded, or as check dams to prevent further sediment from leaving the site. • Check dams can be constructed of either rock or pea-gravel filled bags. Numerous new products are also available for this purpose. They tend to be re-usable, quick and easy to install, effective, and cost efficient. • Check dams should be placed perpendicular to the flow of water. • The maximum spacing between the dams shall be such that the toe of the upstream dam is at the same elevation as the top of the downstream dam. • Keep the maximum height at 2 feet at the center of the dam. • Keep the center of the check dam at least 12 inches lower than the outer edges at natural ground elevation. • Keep the side slopes of the check dam at 2:1 or flatter. • Key the stone into the ditch banks and extend it beyond the abutments a minimum of 18 inches to avoid washouts from overflow around the dam. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-75 • Use filter fabric foundation under a rock or sand bag check dam. If a blanket ditch liner is used, this is not necessary. A piece of organic or synthetic blanket cut to fit will also work for this purpose. • Rock check dams shall be constructed of appropriately sized rock. The rock must be placed by hand or by mechanical means (no dumping of rock to form dam) to achieve complete coverage of the ditch or swale and to ensure that the center of the dam is lower than the edges. The rock used must be large enough to stay in place given the expected design flow through the channel. • In the case of grass-lined ditches and swales, all check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale - unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. • Ensure that channel appurtenances, such as culvert entrances below check dams, are not subject to damage or blockage from displaced stones. Figure 4.13 depicts a typical rock check dam. Maintenance Standards Check dams shall be monitored for performance and sediment accumulation during and after each runoff producing rainfall. Sediment shall be removed when it reaches one half the sump depth. • Anticipate submergence and deposition above the check dam and erosion from high flows around the edges of the dam. • If significant erosion occurs between dams, install a protective riprap liner in that portion of the channel. 4-76 Volume II – Construction Stormwater Pollution Prevention February 2005 Figure 4.13 – Check Dams Figure 4.13 – Check Dams February 2005 Volume II – Construction Stormwater Pollution Prevention 4-77 February 2005 Volume II – Construction Stormwater Pollution Prevention 4-77 BMP C208: Triangular Silt Dike (Geotextile-Encased Check Dam) Purpose Triangular silt dikes may be used as check dams, for perimeter protection, for temporary soil stockpile protection, for drop inlet protection, or as a temporary interceptor dike. Conditions of use May be used in place of straw bales for temporary check dams in ditches of any dimension. • May be used on soil or pavement with adhesive or staples. • TSDs have been used to build temporary: 1. sediment ponds; 2. diversion ditches; 3. concrete wash out facilities; 4. curbing; 5. water bars; 6. level spreaders; and, 7. berms. Design and Installation Specifications Made of urethane foam sewn into a woven geosynthetic fabric. It is triangular, 10 inches to 14 inches high in the center, with a 20-inch to 28-inch base. A 2–foot apron extends beyond both sides of the triangle along its standard section of 7 feet. A sleeve at one end allows attachment of additional sections as needed. • Install with ends curved up to prevent water from flowing around the ends. • The fabric flaps and check dam units are attached to the ground with wire staples. Wire staples should be No. 11 gauge wire and should be 200 mm to 300 mm in length. • When multiple units are installed, the sleeve of fabric at the end of the unit shall overlap the abutting unit and be stapled. • Check dams should be located and installed as soon as construction will allow. • Check dams should be placed perpendicular to the flow of water. • When used as check dams, the leading edge must be secured with rocks, sandbags, or a small key slot and staples. • In the case of grass-lined ditches and swales, check dams and accumulated sediment shall be removed when the grass has matured sufficiently to protect the ditch or swale unless the slope of the swale is greater than 4 percent. The area beneath the check dams shall be seeded and mulched immediately after dam removal. Maintenance Standards • Triangular silt dams shall be monitored for performance and sediment accumulation during and after each runoff producing rainfall. 4-78 Volume II – Construction Stormwater Pollution Prevention February 2005 Sediment shall be removed when it reaches one half the height of the dam. • Anticipate submergence and deposition above the triangular silt dam and erosion from high flows around the edges of the dam. Immediately repair any damage or any undercutting of the dam. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-79 BMP C209: Outlet Protection Purpose Outlet protection prevents scour at conveyance outlets and minimizes the potential for downstream erosion by reducing the velocity of concentrated stormwater flows. Conditions of use Outlet protection is required at the outlets of all ponds, pipes, ditches, or other conveyances, and where runoff is conveyed to a natural or manmade drainage feature such as a stream, wetland, lake, or ditch. Design and Installation Specifications The receiving channel at the outlet of a culvert shall be protected from erosion by rock lining a minimum of 6 feet downstream and extending up the channel sides a minimum of 1–foot above the maximum tailwater elevation or 1-foot above the crown, whichever is higher. For large pipes (more than 18 inches in diameter), the outlet protection lining of the channel is lengthened to four times the diameter of the culvert. • Standard wingwalls, and tapered outlets and paved channels should also be considered when appropriate for permanent culvert outlet protection. (See WSDOT Hydraulic Manual, available through WSDOT Engineering Publications). • Organic or synthetic erosion blankets, with or without vegetation, are usually more effective than rock, cheaper, and easier to install. Materials can be chosen using manufacturer product specifications. ASTM test results are available for most products and the designer can choose the correct material for the expected flow. • With low flows, vegetation (including sod) can be effective. • The following guidelines shall be used for riprap outlet protection: 1. If the discharge velocity at the outlet is less than 5 fps (pipe slope less than 1 percent), use 2-inch to 8-inch riprap. Minimum thickness is 1-foot. 2. For 5 to 10 fps discharge velocity at the outlet (pipe slope less than 3 percent), use 24-inch to 4-foot riprap. Minimum thickness is 2 feet. 3. For outlets at the base of steep slope pipes (pipe slope greater than 10 percent), an engineered energy dissipater shall be used. • Filter fabric or erosion control blankets should always be used under riprap to prevent scour and channel erosion. • New pipe outfalls can provide an opportunity for low-cost fish habitat improvements. For example, an alcove of low-velocity water can be created by constructing the pipe outfall and associated energy dissipater back from the stream edge and digging a channel, over- widened to the upstream side, from the outfall. Overwintering juvenile and migrating adult salmonids may use the alcove as shelter during 4-80 Volume II – Construction Stormwater Pollution Prevention February 2005 high flows. Bank stabilization, bioengineering, and habitat features may be required for disturbed areas. See Volume V for more information on outfall system design. Maintenance Standards • Inspect and repair as needed. • Add rock as needed to maintain the intended function. • Clean energy dissipater if sediment builds up. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-81 BMP C220: Storm Drain Inlet Protection Purpose To prevent coarse sediment from entering drainage systems prior to permanent stabilization of the disturbed area. Conditions of Use Where storm drain inlets are to be made operational before permanent stabilization of the disturbed drainage area. Protection should be provided for all storm drain inlets downslope and within 500 feet of a disturbed or construction area, unless the runoff that enters the catch basin will be conveyed to a sediment pond or trap. Inlet protection may be used anywhere to protect the drainage system. It is likely that the drainage system will still require cleaning. Table 4.9 lists several options for inlet protection. All of the methods for storm drain inlet protection are prone to plugging and require a high frequency of maintenance. Drainage areas should be limited to 1 acre or less. Emergency overflows may be required where stormwater ponding would cause a hazard. If an emergency overflow is provided, additional end-of-pipe treatment may be required. Table 4.9 Storm Drain Inlet Protetion Type of Inlet Protection Emergency Overflow Applicable for Paved/ Earthen Surfaces Conditions of Use Drop Inlet Protection Excavated drop inlet protection Yes, temporary flooding will occur Earthen Applicable for heavy flows. Easy to maintain. Large area Requirement: 30’ X 30’/acre Block and gravel drop inlet protection Yes Paved or Earthen Applicable for heavy concentrated flows. Will not pond. Gravel and wire drop inlet protection No Applicable for heavy concentrated flows. Will pond. Can withstand traffic. Catch basin filters Yes Paved or Earthen Frequent maintenance required. Curb Inlet Protection Curb inlet protection with a wooden weir Small capacity overflow Paved Used for sturdy, more compact installation. Block and gravel curb inlet protection Yes Paved Sturdy, but limited filtration. Culvert Inlet Protection Culvert inlet sediment trap 18 month expected life. 4-82 Volume II – Construction Stormwater Pollution Prevention February 2005 Design and Installation Specifications Excavated Drop Inlet Protection - An excavated impoundment around the storm drain. Sediment settles out of the stormwater prior to entering the storm drain. • Depth 1-2 ft as measured from the crest of the inlet structure. • Side Slopes of excavation no steeper than 2:1. • Minimum volume of excavation 35 cubic yards. • Shape basin to fit site with longest dimension oriented toward the longest inflow area. • Install provisions for draining to prevent standing water problems. • Clear the area of all debris. • Grade the approach to the inlet uniformly. • Drill weep holes into the side of the inlet. • Protect weep holes with screen wire and washed aggregate. • Seal weep holes when removing structure and stabilizing area. • It may be necessary to build a temporary dike to the down slope side of the structure to prevent bypass flow. Block and Gravel Filter - A barrier formed around the storm drain inlet with standard concrete blocks and gravel. See Figure 4.14. • Height 1 to 2 feet above inlet. • Recess the first row 2 inches into the ground for stability. • Support subsequent courses by placing a 2x4 through the block opening. • Do not use mortar. • Lay some blocks in the bottom row on their side for dewatering the pool. • Place hardware cloth or comparable wire mesh with ½-inch openings over all block openings. • Place gravel just below the top of blocks on slopes of 2:1 or flatter. • An alternative design is a gravel donut. • Inlet slope of 3:1. • Outlet slope of 2:1. • 1-foot wide level stone area between the structure and the inlet. • Inlet slope stones 3 inches in diameter or larger. • Outlet slope use gravel ½- to ¾-inch at a minimum thickness of 1-foot. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-83 Figure 4.14 – Block and Gravel Filter Gravel and Wire Mesh Filter - A gravel barrier placed over the top of the inlet. This structure does not provide an overflow. Ponding Height Notes: 1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%) 2. Excavate a basin of sufficient size adjacent to the drop inlet. 3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure. • Hardware cloth or comparable wire mesh with ½-inch openings. • Coarse aggregate. • Height 1-foot or more, 18 inches wider than inlet on all sides. • Place wire mesh over the drop inlet so that the wire extends a minimum of 1-foot beyond each side of the inlet structure. • If more than one strip of mesh is necessary, overlap the strips. • Place coarse aggregate over the wire mesh. • The depth of the gravel should be at least 12 inches over the entire inlet opening and extend at least 18 inches on all sides. 4-84 Volume II – Construction Stormwater Pollution Prevention February 2005 Catchbasin Filters - Inserts should be designed by the manufacturer for use at construction sites. The limited sediment storage capacity increases the amount of inspection and maintenance required, which may be daily for heavy sediment loads. The maintenance requirements can be reduced by combining a catchbasin filter with another type of inlet protection. This type of inlet protection provides flow bypass without overflow and therefore may be a better method for inlets located along active rights-of- way. • 5 cubic feet of storage. • Dewatering provisions. • High-flow bypass that will not clog under normal use at a construction site. • The catchbasin filter is inserted in the catchbasin just below the grating. Curb Inlet Protection with Wooden Weir – Barrier formed around a curb inlet with a wooden frame and gravel. • Wire mesh with ½-inch openings. • Extra strength filter cloth. • Construct a frame. • Attach the wire and filter fabric to the frame. • Pile coarse washed aggregate against wire/fabric. • Place weight on frame anchors. Block and Gravel Curb Inlet Protection – Barrier formed around an inlet with concrete blocks and gravel. See Figure 4.14. • Wire mesh with ½-inch openings. • Place two concrete blocks on their sides abutting the curb at either side of the inlet opening. These are spacer blocks. • Place a 2x4 stud through the outer holes of each spacer block to align the front blocks. • Place blocks on their sides across the front of the inlet and abutting the spacer blocks. • Place wire mesh over the outside vertical face. • Pile coarse aggregate against the wire to the top of the barrier. Curb and Gutter Sediment Barrier – Sandbag or rock berm (riprap and aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure 4.16. • Construct a horseshoe shaped berm, faced with coarse aggregate if using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet. • Construct a horseshoe shaped sedimentation trap on the outside of the berm sized to sediment trap standards for protecting a culvert inlet. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-85 Maintenance Standards • Catch basin filters should be inspected frequently, especially after storm events. If the insert becomes clogged, it should be cleaned or replaced. • For systems using stone filters: If the stone filter becomes clogged with sediment, the stones must be pulled away from the inlet and cleaned or replaced. Since cleaning of gravel at a construction site may be difficult, an alternative approach would be to use the clogged stone as fill and put fresh stone around the inlet. • Do not wash sediment into storm drains while cleaning. Spread all excavated material evenly over the surrounding land area or stockpile and stabilize as appropriate. 4-86 Volume II – Construction Stormwater Pollution Prevention February 2005 Figure 4.15 – Block and Gravel Curb Inlet Protection A Plan View Wire Screen or Filt er Fabric Catch Basin Curb Inlet Concrete Block Ponding Height Overflow 2x4 Wood Stud (100x50 Timber Stud) Concrete Block Wire Screen or Filter Fabric Curb Inlet ¾" Drai n Gravel (20mm) ¾" Drain Gravel (20mm)Section A - A Back of Curb Concrete Block 2x4 Wood Stud Catch Basi nBack of Sidewalk NOTES: 1. Use block and gravel type sediment barrier when curb inlet is located in gentl y sloping street segment, where water can pond and allow sediment to separate from runoff. 2. Barrier shal l allow for overflow from severe storm event. 3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from the traveled way immediately. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-87 Figure 4.16 – Curb and Gutter Barrier Figure 4.16 – Curb and Gutter Barrier 4-88 Volume II – Construction Stormwater Pollution Prevention February 2005 4-88 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C233: Silt Fence Purpose Use of a silt fence reduces the transport of coarse sediment from a construction site by providing a temporary physical barrier to sediment and reducing the runoff velocities of overland flow. See Figure 4.19 for details on silt fence construction. Conditions of Use Silt fence may be used downslope of all disturbed areas. • Silt fence is not intended to treat concentrated flows, nor is it intended to treat substantial amounts of overland flow. Any concentrated flows must be conveyed through the drainage system to a sediment pond. The only circumstance in which overland flow can be treated solely by a silt fence, rather than by a sediment pond, is when the area draining to the fence is one acre or less and flow rates are less than 0.5 cfs. • Silt fences should not be constructed in streams or used in V-shaped ditches. They are not an adequate method of silt control for anything deeper than sheet or overland flow. Figure 4.19 – Silt Fence Design and Installation Specifications • Drainage area of 1 acre or less or in combination with sediment basin in a larger site. • Maximum slope steepness (normal (perpendicular) to fence line) 1:1. • Maximum sheet or overland flow path length to the fence of 100 feet. • No flows greater than 0.5 cfs. • The geotextile used shall meet the following standards. All geotextile properties listed below are minimum average roll values (i.e., the test result for any sampled roll in a lot shall meet or exceed the values shown in Table 4.10): 4-94 Volume II – Construction Stormwater Pollution Prevention February 2005 Table 4.10 Geotextile Standards Polymeric Mesh AOS (ASTM D4751) 0.60 mm maximum for slit film wovens (#30 sieve). 0.30 mm maximum for all other geotextile types (#50 sieve). 0.15 mm minimum for all fabric types (#100 sieve). Water Permittivity (ASTM D4491) 0.02 sec-1 minimum Grab Tensile Strength (ASTM D4632) 180 lbs. Minimum for extra strength fabric. 100 lbs minimum for standard strength fabric. Grab Tensile Strength (ASTM D4632) 30% maximum Ultraviolet Resistance (ASTM D4355) 70% minimum • Standard strength fabrics shall be supported with wire mesh, chicken wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the strength of the fabric. Silt fence materials are available that have synthetic mesh backing attached. • Filter fabric material shall contain ultraviolet ray inhibitors and stabilizers to provide a minimum of six months of expected usable construction life at a temperature range of 0°F. to 120°F. • 100 percent biodegradable silt fence is available that is strong, long lasting, and can be left in place after the project is completed, if permitted by local regulations. • Standard Notes for construction plans and specifications follow. Refer to Figure 4.19 for standard silt fence details. The contractor shall install and maintain temporary silt fences at the locations shown in the Plans. The silt fences shall be constructed in the areas of clearing, grading, or drainage prior to starting those activities. A silt fence shall not be considered temporary if the silt fence must function beyond the life of the contract. The silt fence shall prevent soil carried by runoff water from going beneath, through, or over the top of the silt fence, but shall allow the water to pass through the fence. The minimum height of the top of silt fence shall be 2 feet and the maximum height shall be 2½ feet above the original ground surface. The geotextile shall be sewn together at the point of manufacture, or at an approved location as determined by the Engineer, to form geotextile lengths as required. All sewn seams shall be located at a support post. Alternatively, two sections of silt fence can be overlapped, provided the Contractor can demonstrate, to the satisfaction of the Engineer, that the overlap is long enough and that the adjacent fence sections are close enough together to prevent silt laden water from escaping through the fence at the overlap. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-95 The geotextile shall be attached on the up-slope side of the posts and support system with staples, wire, or in accordance with the manufacturer's recommendations. The geotextile shall be attached to the posts in a manner that reduces the potential for geotextile tearing at the staples, wire, or other connection device. Silt fence back-up support for the geotextile in the form of a wire or plastic mesh is dependent on the properties of the geotextile selected for use. If wire or plastic back-up mesh is used, the mesh shall be fastened securely to the up-slope of the posts with the geotextile being up-slope of the mesh back-up support. The geotextile at the bottom of the fence shall be buried in a trench to a minimum depth of 4 inches below the ground surface. The trench shall be backfilled and the soil tamped in place over the buried portion of the geotextile, such that no flow can pass beneath the fence and scouring can not occur. When wire or polymeric back-up support mesh is used, the wire or polymeric mesh shall extend into the trench a minimum of 3 inches. The fence posts shall be placed or driven a minimum of 18 inches. A minimum depth of 12 inches is allowed if topsoil or other soft subgrade soil is not present and a minimum depth of 18 inches cannot be reached. Fence post depths shall be increased by 6 inches if the fence is located on slopes of 3:1 or steeper and the slope is perpendicular to the fence. If required post depths cannot be obtained, the posts shall be adequately secured by bracing or guying to prevent overturning of the fence due to sediment loading. Silt fences shall be located on contour as much as possible, except at the ends of the fence, where the fence shall be turned uphill such that the silt fence captures the runoff water and prevents water from flowing around the end of the fence. If the fence must cross contours, with the exception of the ends of the fence, gravel check dams placed perpendicular to the back of the fence shall be used to minimize concentrated flow and erosion along the back of the fence. The gravel check dams shall be approximately 1- foot deep at the back of the fence. It shall be continued perpendicular to the fence at the same elevation until the top of the check dam intercepts the ground surface behind the fence. The gravel check dams shall consist of crushed surfacing base course, gravel backfill for walls, or shoulder ballast. The gravel check dams shall be located every 10 feet along the fence where the fence must cross contours. The slope of the fence line where contours must be crossed shall not be steeper than 3:1. Wood, steel or equivalent posts shall be used. Wood posts shall have minimum dimensions of 2 inches by 2 inches by 3 feet minimum length, and shall be free of defects such as knots, splits, or gouges. 4-96 Volume II – Construction Stormwater Pollution Prevention February 2005 Steel posts shall consist of either size No. 6 rebar or larger, ASTM A 120 steel pipe with a minimum diameter of 1-inch, U, T, L, or C shape steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts having equivalent strength and bending resistance to the post sizes listed. The spacing of the support posts shall be a maximum of 6 feet. Fence back-up support, if used, shall consist of steel wire with a maximum mesh spacing of 2 inches, or a prefabricated polymeric mesh. The strength of the wire or polymeric mesh shall be equivalent to or greater than 180 lbs. grab tensile strength. The polymeric mesh must be as resistant to ultraviolet radiation as the geotextile it supports. • Silt fence installation using the slicing method specification details follow. Refer to Figure 4.20 for slicing method details. The base of both end posts must be at least 2 to 4 inches above the top of the silt fence fabric on the middle posts for ditch checks to drain properly. Use a hand level or string level, if necessary, to mark base points before installation. Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet apart in standard applications. Install posts 24 inches deep on the downstream side of the silt fence, and as close as possible to the fabric, enabling posts to support the fabric from upstream water pressure. Install posts with the nipples facing away from the silt fence fabric. Attach the fabric to each post with three ties, all spaced within the top 8 inches of the fabric. Attach each tie diagonally 45 degrees through the fabric, with each puncture at least 1 inch vertically apart. In addition, each tie should be positioned to hang on a post nipple when tightening to prevent sagging. Wrap approximately 6 inches of fabric around the end posts and secure with 3 ties. No more than 24 inches of a 36-inch fabric is allowed above ground level. The rope lock system must be used in all ditch check applications. The installation should be checked and corrected for any deviation before compaction. Use a flat-bladed shovel to tuck fabric deeper into the ground if necessary. Compaction is vitally important for effective results. Compact the soil immediately next to the silt fence fabric with the front wheel of the tractor, skid steer, or roller exerting at least 60 pounds per square inch. Compact the upstream side first and then each side twice for a total of four trips. February 2005 Volume II – Construction Stormwater Pollution Prevention 4-97 Maintenance Standards • Any damage shall be repaired immediately. • If concentrated flows are evident uphill of the fence, they must be intercepted and conveyed to a sediment pond. • It is important to check the uphill side of the fence for signs of the fence clogging and acting as a barrier to flow and then causing channelization of flows parallel to the fence. If this occurs, replace the fence or remove the trapped sediment. • Sediment deposits shall either be removed when the deposit reaches approximately one-third the height of the silt fence, or a second silt fence shall be installed. • If the filter fabric (geotextile) has deteriorated due to ultraviolet breakdown, it shall be replaced. Figure 4.20 – Silt Fence Installation by Slicing Method 4-98 Volume II – Construction Stormwater Pollution Prevention February 2005 BMP C235: Straw Wattles Purpose Straw wattles are temporary erosion and sediment control barriers consisting of straw that is wrapped in biodegradable tubular plastic or similar encasing material. They reduce the velocity and can spread the flow of rill and sheet runoff, and can capture and retain sediment. Straw wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length. The wattles are placed in shallow trenches and staked along the contour of disturbed or newly constructed slopes. See Figure 4.21 for typical construction details. Conditions of Use • Disturbed areas that require immediate erosion protection. • Exposed soils during the period of short construction delays, or over winter months. • On slopes requiring stabilization until permanent vegetation can be established. • Straw wattles are effective for one to two seasons. • If conditions are appropriate, wattles can be staked to the ground using willow cuttings for added revegetation. • Rilling can occur beneath wattles if not properly entrenched and water can pass between wattles if not tightly abutted together. Design Criteria • It is critical that wattles are installed perpendicular to the flow direction and parallel to the slope contour. • Narrow trenches should be dug across the slope on contour to a depth of 3 to 5 inches on clay soils and soils with gradual slopes. On loose soils, steep slopes, and areas with high rainfall, the trenches should be dug to a depth of 5 to 7 inches, or 1/2 to 2/3 of the thickness of the wattle. • Start building trenches and installing wattles from the base of the slope and work up. Excavated material should be spread evenly along the uphill slope and compacted using hand tamping or other methods. • Construct trenches at contour intervals of 3 to 30 feet apart depending on the steepness of the slope, soil type, and rainfall. The steeper the slope the closer together the trenches. • Install the wattles snugly into the trenches and abut tightly end to end. Do not overlap the ends. • Install stakes at each end of the wattle, and at 4-foot centers along entire length of wattle. • If required, install pilot holes for the stakes using a straight bar to drive holes through the wattle and into the soil. • At a minimum, wooden stakes should be approximately 3/4 x 3/4 x 24 inches. Willow cuttings or 3/8-inch rebar can also be used for stakes. 4-100 Volume II – Construction Stormwater Pollution Prevention February 2005 Maintenance Standards • Stakes should be driven through the middle of the wattle, leaving 2 to 3 inches of the stake protruding above the wattle. • Wattles may require maintenance to ensure they are in contact with soil and thoroughly entrenched, especially after significant rainfall on steep sandy soils. • Inspect the slope after significant storms and repair any areas where wattles are not tightly abutted or water has scoured beneath the wattles. Figure 4.21 – Straw Wattles February 2005 Volume II – Construction Stormwater Pollution Prevention 4-101 Appendix C - Correspondence File Future Correspondence Here Appendix D - Site Inspection Form Construction Stormwater Site Inspection Form Page 1 Project Name Permit # Inspection Date Time Name of Certified Erosion Sediment Control Lead (CESCL) or qualified inspector if less than one acre Print Name: Approximate rainfall amount since the last inspection (in inches): Approximate rainfall amount in the last 24 hours (in inches): Current Weather Clear Cloudy Mist Rain Wind Fog A. Type of inspection: Weekly Post Storm Event Other B. Phase of Active Construction (check all that apply): Pre Construction/installation of erosion/sediment controls Clearing/Demo/Grading Infrastructure/storm/roads Concrete pours Vertical Construction/buildings Utilities Offsite improvements Site temporary stabilized Final stabilization C. Questions: 1. Were all areas of construction and discharge points inspected? Yes No 2. Did you observe the presence of suspended sediment, turbidity, discoloration, or oil sheen Yes No 3. Was a water quality sample taken during inspection? (refer to permit conditions S4 & S5) Yes No 4. Was there a turbid discharge 250 NTU or greater, or Transparency 6 cm or less?* Yes No 5. If yes to #4 was it reported to Ecology? Yes No 6. Is pH sampling required? pH range required is 6.5 to 8.5. Yes No If answering yes to a discharge, describe the event. Include when, where, and why it happened; what action was taken, and when. *If answering yes to # 4 record NTU/Transparency with continual sampling daily until turbidity is 25 NTU or less/ transparency is 33 cm or greater. Sampling Results: Date: Parameter Method (circle one) Result Other/Note NTU cm pH Turbidity tube, meter, laboratory pH Paper, kit, meter Construction Stormwater Site Inspection Form Page 2 D. Check the observed status of all items. Provide “Action Required “details and dates. Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 1 Clearing Limits Before beginning land disturbing activities are all clearing limits, natural resource areas (streams, wetlands, buffers, trees) protected with barriers or similar BMPs? (high visibility recommended) 2 Construction Access Construction access is stabilized with quarry spalls or equivalent BMP to prevent sediment from being tracked onto roads? Sediment tracked onto the road way was cleaned thoroughly at the end of the day or more frequent as necessary. 3 Control Flow Rates Are flow control measures installed to control stormwater volumes and velocity during construction and do they protect downstream properties and waterways from erosion? If permanent infiltration ponds are used for flow control during construction, are they protected from siltation? 4 Sediment Controls All perimeter sediment controls (e.g. silt fence, wattles, compost socks, berms, etc.) installed, and maintained in accordance with the Stormwater Pollution Prevention Plan (SWPPP). Sediment control BMPs (sediment ponds, traps, filters etc.) have been constructed and functional as the first step of grading. Stormwater runoff from disturbed areas is directed to sediment removal BMP. 5 Stabilize Soils Have exposed un-worked soils been stabilized with effective BMP to prevent erosion and sediment deposition? Construction Stormwater Site Inspection Form Page 3 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 5 Stabilize Soils Cont. Are stockpiles stabilized from erosion, protected with sediment trapping measures and located away from drain inlet, waterways, and drainage channels? Have soils been stabilized at the end of the shift, before a holiday or weekend if needed based on the weather forecast? 6 Protect Slopes Has stormwater and ground water been diverted away from slopes and disturbed areas with interceptor dikes, pipes and or swales? Is off-site storm water managed separately from stormwater generated on the site? Is excavated material placed on uphill side of trenches consistent with safety and space considerations? Have check dams been placed at regular intervals within constructed channels that are cut down a slope? 7 Drain Inlets Storm drain inlets made operable during construction are protected. Are existing storm drains within the influence of the project protected? 8 Stabilize Channel and Outlets Have all on-site conveyance channels been designed, constructed and stabilized to prevent erosion from expected peak flows? Is stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes and downstream conveyance systems? 9 Control Pollutants Are waste materials and demolition debris handled and disposed of to prevent contamination of stormwater? Has cover been provided for all chemicals, liquid products, petroleum products, and other material? Has secondary containment been provided capable of containing 110% of the volume? Were contaminated surfaces cleaned immediately after a spill incident? Were BMPs used to prevent contamination of stormwater by a pH modifying sources? Construction Stormwater Site Inspection Form Page 4 Element # Inspection BMPs Inspected BMP needs maintenance BMP failed Action required (describe in section F) yes no n/a 9 Cont. Wheel wash wastewater is handled and disposed of properly. 10 Control Dewatering Concrete washout in designated areas. No washout or excess concrete on the ground. Dewatering has been done to an approved source and in compliance with the SWPPP. Were there any clean non turbid dewatering discharges? 11 Maintain BMP Are all temporary and permanent erosion and sediment control BMPs maintained to perform as intended? 12 Manage the Project Has the project been phased to the maximum degree practicable? Has regular inspection, monitoring and maintenance been performed as required by the permit? Has the SWPPP been updated, implemented and records maintained? 13 Protect LID Is all Bioretention and Rain Garden Facilities protected from sedimentation with appropriate BMPs? Is the Bioretention and Rain Garden protected against over compaction of construction equipment and foot traffic to retain its infiltration capabilities? Permeable pavements are clean and free of sediment and sediment laden- water runoff. Muddy construction equipment has not been on the base material or pavement. Have soiled permeable pavements been cleaned of sediments and pass infiltration test as required by stormwater manual methodology? Heavy equipment has been kept off existing soils under LID facilities to retain infiltration rate. E. Check all areas that have been inspected. All in place BMPs All disturbed soils All concrete wash out area All material storage areas All discharge locations All equipment storage areas All construction entrances/exits Construction Stormwater Site Inspection Form Page 5 F. Elements checked “Action Required” (section D) describe corrective action to be taken. List the element number; be specific on location and work needed. Document, initial, and date when the corrective action has been completed and inspected. Element # Description and Location Action Required Completion Date Initials Attach additional page if needed Sign the following certification: “I certify that this report is true, accurate, and complete, to the best of my knowledge and belief” Inspected by: (print) (Signature) Date: Title/Qualification of Inspector: Appendix E - Construction Stormwater General Permit (CSWGP) Construction Stormwater General Permit Page 2 TABLE OF CONTENTS LIST OF TABLES ...........................................................................................................................3 SUMMARY OF PERMIT REPORT SUBMITTALS .....................................................................4 SPECIAL CONDITIONS ................................................................................................................5 S1. PERMIT COVERAGE ........................................................................................................5 S2. APPLICATION REQUIREMENTS ...................................................................................8 S3. COMPLIANCE WITH STANDARDS .............................................................................12 S4. MONITORING REQUIREMENTS, BENCHMARKS, AND REPORTING TRIGGERS ................................................................................................13 S5. REPORTING AND RECORDKEEPING REQUIREMENTS .........................................20 S6. PERMIT FEES...................................................................................................................23 S7. SOLID AND LIQUID WASTE DISPOSAL ....................................................................23 S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES ................................................23 S9. STORMWATER POLLUTION PREVENTION PLAN...................................................27 S10. NOTICE OF TERMINATION .........................................................................................37 GENERAL CONDITIONS ...........................................................................................................38 G1. DISCHARGE VIOLATIONS ...........................................................................................38 G2. SIGNATORY REQUIREMENTS.....................................................................................38 G3. RIGHT OF INSPECTION AND ENTRY .........................................................................39 G4. GENERAL PERMIT MODIFICATION AND REVOCATION ......................................39 G5. REVOCATION OF COVERAGE UNDER THE PERMIT .............................................39 G6. REPORTING A CAUSE FOR MODIFICATION ............................................................40 G7. COMPLIANCE WITH OTHER LAWS AND STATUTES .............................................40 G8. DUTY TO REAPPLY .......................................................................................................40 G9. TRANSFER OF GENERAL PERMIT COVERAGE .......................................................41 G10. REMOVED SUBSTANCES .............................................................................................41 G11. DUTY TO PROVIDE INFORMATION ...........................................................................41 G12. OTHER REQUIREMENTS OF 40 CFR ...........................................................................41 G13. ADDITIONAL MONITORING ........................................................................................41 G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS .............................................41 G15. UPSET ...............................................................................................................................42 G16. PROPERTY RIGHTS ........................................................................................................42 Construction Stormwater General Permit Page 3 G17. DUTY TO COMPLY ........................................................................................................42 G18. TOXIC POLLUTANTS.....................................................................................................42 G19. PENALTIES FOR TAMPERING .....................................................................................43 G20. REPORTING PLANNED CHANGES .............................................................................43 G21. REPORTING OTHER INFORMATION ..........................................................................43 G22. REPORTING ANTICIPATED NON-COMPLIANCE .....................................................43 G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT ..........44 G24. APPEALS ..........................................................................................................................44 G25. SEVERABILITY ...............................................................................................................44 G26. BYPASS PROHIBITED ....................................................................................................44 APPENDIX A – DEFINITIONS ...................................................................................................47 APPENDIX B – ACRONYMS .....................................................................................................55 LIST OF TABLES Table 1: Summary of Required Submittals ................................................................................... 4 Table 2: Summary of Required On-site Documentation............................................................... 4 Table 3: Summary of Primary Monitoring Requirements .......................................................... 15 Table 4: Monitoring and Reporting Requirements ..................................................................... 17 Table 5: Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters .................................................................................................... 25 Table 6: pH Sampling and Limits for 303(d)-Listed Waters ...................................................... 26 Construction Stormwater General Permit Page 4 SUMMARY OF PERMIT REPORT SUBMITTALS Refer to the Special and General Conditions within this permit for additional submittal requirements. Appendix A provides a list of definitions. Appendix B provides a list of acronyms. Table 1: Summary of Required Submittals Permit Section Submittal Frequency First Submittal Date S5.A and S8 High Turbidity/Transparency Phone Reporting As Necessary Within 24 hours S5.B Discharge Monitoring Report Monthly* Within 15 days following the end of each month S5.F and S8 Noncompliance Notification – Telephone Notification As necessary Within 24-hours S5.F Noncompliance Notification – Written Report As necessary Within 5 Days of non- compliance S9.C Request for Chemical Treatment Form As necessary Written approval from Ecology is required prior to using chemical treatment (with the exception of dry ice or CO2 to adjust pH) G2 Notice of Change in Authorization As necessary G6 Permit Application for Substantive Changes to the Discharge As necessary G8 Application for Permit Renewal 1/permit cycle No later than 180 days before expiration G9 Notice of Permit Transfer As necessary G20 Notice of Planned Changes As necessary G22 Reporting Anticipated Non- compliance As necessary SPECIAL NOTE: *Permittees must submit electronic Discharge Monitoring Reports (DMRs) to the Washington State Department of Ecology monthly, regardless of site discharge, for the full duration of permit coverage . Refer to Section S5.B of this General Permit for more specific information regarding DMRs. Table 2: Summary of Required On-site Documentation Document Title Permit Conditions Permit Coverage Letter See Conditions S2, S5 Construction Stormwater General Permit See Conditions S2, S5 Site Log Book See Conditions S4, S5 Stormwater Pollution Prevention Plan (SWPPP) See Conditions S9, S5 Construction Stormwater General Permit Page 5 SPECIAL CONDITIONS S1. PERMIT COVERAGE A. Permit Area This Construction Stormwater General Permit (CSWGP) covers all areas of Washington State, except for federal operators and Indian Country as specified in Special Condition S1.E.3. B. Operators Required to Seek Coverage Under this General Permit: 1. Operators of the following construction activities are required to seek coverage under this CSWGP: a. Clearing, grading and/or excavation that results in the disturbance of one or more acres (including off-site disturbance acreage authorized in S1.C.2) and discharges stormwater to surface waters of the State; and clearing, grading and/or excavation on sites smaller than one acre that are part of a larger common plan of development or sale, if the common plan of development or sale will ultimately disturb one acre or more and discharge stormwater to surface waters of the State. i. This includes forest practices (including, but not limited to, class IV conversions) that are part of a construction activity that will result in the disturbance of one or more acres, and discharge to surface waters of the State (that is, forest practices that prepare a site for construction activities); and b. Any size construction activity discharging stormwater to waters of the State that the Washington State Department of Ecology (Ecology): i. Determines to be a significant contributor of pollutants to waters of the State of Washington. ii. Reasonably expects to cause a violation of any water quality standard. 2. Operators of the following activities are not required to seek coverage under this CSWGP (unless specifically required under Special Condition S1.B.1.b. above): a. Construction activities that discharge all stormwater and non-stormwater to ground water, sanitary sewer, or combined sewer, and have no point source discharge to either surface water or a storm sewer system that drains to surface waters of the State. b. Construction activities covered under an Erosivity Waiver (Special Condition S2.C). c. Routine maintenance that is performed to maintain the original line and grade, hydraulic capacity, or original purpose of a facility. Construction Stormwater General Permit Page 6 C. Authorized Discharges: 1. Stormwater Associated with Construction Activity. Subject to compliance with the terms and conditions of this permit, Permittees are authorized to discharge stormwater associated with construction activity to surface waters of the State or to a storm sewer system that drains to surface waters of the State. (Note that “surface waters of the State” may exist on a construction site as well as off site; for example, a creek running through a site.) 2. Stormwater Associated with Construction Support Activity. This permit also authorizes stormwater discharge from support activities related to the permitted construction site (for example, an on-site portable rock crusher, off-site equipment staging yards, material storage areas, borrow areas, etc.) provided: a. The support activity relates directly to the permitted construction site that is required to have an NPDES permit; and b. The support activity is not a commercial operation serving multiple unrelated construction projects, and does not operate beyond the completion of the construction activity; and c. Appropriate controls and measures are identified in the Stormwater Pollution Prevention Plan (SWPPP) for the discharges from the support activity areas. 3. Non-Stormwater Discharges. The categories and sources of non-stormwater discharges identified below are authorized conditionally, provided the discharge is consistent with the terms and conditions of this permit: a. Discharges from fire-fighting activities. b. Fire hydrant system flushing. c. Potable water, including uncontaminated water line flushing. d. Hydrostatic test water. e. Uncontaminated air conditioning or compressor condensate. f. Uncontaminated ground water or spring water. g. Uncontaminated excavation dewatering water (in accordance with S9.D.10). h. Uncontaminated discharges from foundation or footing drains. i. Uncontaminated water used to control dust. Permittees must minimize the amount of dust control water used. j. Routine external building wash down that does not use detergents. k. Landscape irrigation water. The SWPPP must adequately address all authorized non-stormwater discharges, except for discharges from fire-fighting activities, and must comply with Special Condition S3. Construction Stormwater General Permit Page 7 At a minimum, discharges from potable water (including water line flushing), fire hydrant system flushing, and pipeline hydrostatic test water must undergo the following: dechlorination to a concentration of 0.1 parts per million (ppm) or less, and pH adjustment to within 6.5 – 8.5 standard units (su), if necessary. D. Prohibited Discharges: The following discharges to waters of the State, including ground water, are prohibited. 1. Concrete wastewater. 2. Wastewater from washout and clean-up of stucco, paint, form release oils, curing compounds and other construction materials. 3. Process wastewater as defined by 40 Code of Federal Regulations (CFR) 122.2 (see Appendix A of this permit). 4. Slurry materials and waste from shaft drilling, including process wastewater from shaft drilling for construction of building, road, and bridge foundations unless managed according to Special Condition S9.D.9.j. 5. Fuels, oils, or other pollutants used in vehicle and equipment operation and maintenance. 6. Soaps or solvents used in vehicle and equipment washing. 7. Wheel wash wastewater, unless managed according to Special Condition S9.D.9. 8. Discharges from dewatering activities, including discharges from dewatering of trenches and excavations, unless managed according to Special Condition S9.D.10. E. Limits on Coverage Ecology may require any discharger to apply for and obtain coverage under an individual permit or another more specific general permit. Such alternative coverage will be required when Ecology determines that this CSWGP does not provide adequate assurance that water quality will be protected, or there is a reasonable potential for the project to cause or contribute to a violation of water quality standards. The following stormwater discharges are not covered by this permit: 1. Post-construction stormwater discharges that originate from the site after completion of construction activities and the site has undergone final stabilization. 2. Non-point source silvicultural activities such as nursery operations, site preparation, reforestation and subsequent cultural treatment, thinning, prescribed burning, pest and fire control, harvesting operations, surface drainage, or road construction and maintenance, from which there is natural runoff as excluded in 40 CFR Subpart 122. 3. Stormwater from any federal operator. Construction Stormwater General Permit Page 8 4. Stormwater from facilities located on “Indian Country” as defined in 18 U.S.C.§1151, except portions of the Puyallup Reservation as noted below. Indian Country includes: a. All land within any Indian Reservation notwithstanding the issuance of any patent, and, including rights-of-way running through the reservation. This includes all federal, tribal, and Indian and non-Indian privately owned land within the reservation. b. All off-reservation Indian allotments, the Indian titles to which have not been extinguished, including rights-of-way running through the same. c. All off-reservation federal trust lands held for Native American Tribes. Puyallup Exception: Following the Puyallup Tribes of Indians Land Settlement Act of 1989, 25 U.S.C. §1773; the permit does apply to land within the Puyallup Reservation except for discharges to surface water on land held in trust by the federal government. 5. Stormwater from any site covered under an existing NPDES individual permit in which stormwater management and/or treatment requirements are included for all stormwater discharges associated with construction activity. 6. Stormwater from a site where an applicable Total Maximum Daily Load (TMDL) requirement specifically precludes or prohibits discharges from construction activity. S2. APPLICATION REQUIREMENTS A. Permit Application Forms 1. Notice of Intent Form/Timeline a. Operators of new or previously unpermitted construction activities must submit a complete and accurate permit application (Notice of Intent, or NOI) to Ecology. b. Operators must apply using the electronic application form (NOI) available on Ecology’s website http://www.ecy.wa.gov/programs/wq/stormwater/ construction/index.html. Permittees unable to submit electronically (for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Construction Stormwater General Permit Page 9 c. The operator must submit the NOI at least 60 days before discharging stormwater from construction activities and must submit it on or before the date of the first public notice (see Special Condition S2.B below for details). The 30- day public comment period begins on the publication date of the second public notice. Unless Ecology responds to the complete application in writing, based on public comments, or any other relevant factors, coverage under the general permit will automatically commence on the thirty-first day following receipt by Ecology of a completed NOI, or the issuance date of this permit, whichever is later; unless Ecology specifies a later date in writing as required by WAC173- 226-200(2). d. If an applicant intends to use a Best Management Practice (BMP) selected on the basis of Special Condition S9.C.4 (“demonstrably equivalent” BMPs), the applicant must notify Ecology of its selection as part of the NOI. In the event the applicant selects BMPs after submission of the NOI, it must provide notice of the selection of an equivalent BMP to Ecology at least 60 days before intended use of the equivalent BMP. e. Permittees must notify Ecology regarding any changes to the information provided on the NOI by submitting an updated NOI. Examples of such changes include, but are not limited to: i. Changes to the Permittee’s mailing address, ii. Changes to the on-site contact person information, and iii. Changes to the area/acreage affected by construction activity. f. Applicants must notify Ecology if they are aware of contaminated soils and/or groundwater associated with the construction activity. Provide detailed information with the NOI (as known and readily available) on the nature and extent of the contamination (concentrations, locations, and depth), as well as pollution prevention and/or treatment BMPs proposed to control the discharge of soil and/or groundwater contaminants in stormwater. Examples of such detail may include, but are not limited to: i. List or table of all known contaminants with laboratory test results showing concentration and depth, ii. Map with sample locations, iii. Temporary Erosion and Sediment Control (TESC) plans, iv. Related portions of the Stormwater Pollution Prevention Plan (SWPPP) that address the management of contaminated and potentially contaminated construction stormwater and dewatering water, v. Dewatering plan and/or dewatering contingency plan. Construction Stormwater General Permit Page 10 2. Transfer of Coverage Form The Permittee can transfer current coverage under this permit to one or more new operators, including operators of sites within a Common Plan of Development, provided the Permittee submits a Transfer of Coverage Form in accordance with General Condition G9. Transfers do not require public notice. B. Public Notice For new or previously unpermitted construction activities, the applicant must publish a public notice at least one time each week for two consecutive weeks, at least 7 days apart, in a newspaper with general circulation in the county where the construction is to take place. The notice must contain: 1. A statement that “The applicant is seeking coverage under the Washington State Department of Ecology’s Construction Stormwater NPDES and State Waste Discharge General Permit”. 2. The name, address and location of the construction site. 3. The name and address of the applicant. 4. The type of construction activity that will result in a discharge (for example, residential construction, commercial construction, etc.), and the number of acres to be disturbed. 5. The name of the receiving water(s) (that is, the surface water(s) to which the site will discharge), or, if the discharge is through a storm sewer system, the name of the operator of the system. 6. The statement: “Any persons desiring to present their views to the Washington State Department of Ecology regarding this application, or interested in Ecology’s action on this application, may notify Ecology in writing no later than 30 days of the last date of publication of this notice. Ecology reviews public comments and considers whether discharges from this project would cause a measurable change in receiving water quality, and, if so, whether the project is necessary and in the overriding public interest according to Tier II antidegradation requirements und er WAC 173-201A-320. Comments can be submitted to: Department of Ecology, PO Box 47696, Olympia, Washington 98504-7696 Attn: Water Quality Program, Construction Stormwater.” Construction Stormwater General Permit Page 11 C. Erosivity Waiver Construction site operators may qualify for an erosivity waiver from the CSWGP if the following conditions are met: 1. The site will result in the disturbance of fewer than 5 acres and the site is not a portion of a common plan of development or sale that will disturb 5 acres or greater. 2. Calculation of Erosivity “R” Factor and Regional Timeframe: a. The project’s rainfall erosivity factor (“R” Factor) must be less than 5 during the period of construction activity, as calculated (see the CSWGP homepage http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html for a link to the EPA’s calculator and step by step instructions on computing the “R” Factor in the EPA Erosivity Waiver Fact Sheet). The period of construction activity starts when the land is first disturbed and ends with final stabilization. In addition: b. The entire period of construction activity must fall within the following timeframes: i. For sites west of the Cascades Crest: June 15 – September 15. ii. For sites east of the Cascades Crest, excluding the Central Basin: June 15 – October 15. iii. For sites east of the Cascades Crest, within the Central Basin: no additional timeframe restrictions apply. The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. For a map of the Central Basin (Average Annual Precipitation Region 2), refer to http://www.ecy.wa.gov/programs/wq/stormwater/ construction/resourcesguidance.html. 3. Construction site operators must submit a complete Erosivity Waiver certification form at least one week before disturbing the land. Certification must include statements that the operator will: a. Comply with applicable local stormwater requirements; and b. Implement appropriate erosion and sediment control BMPs to prevent violations of water quality standards. 4. This waiver is not available for facilities declared significant contributors of pollutants as defined in Special Condition S1.B.1.b. or for any size construction activity that could reasonably expect to cause a violation of any water quality standard as defined in Special Condition S1.B.1.b.ii. 5. This waiver does not apply to construction activities which include non- stormwater discharges listed in Special Condition S1.C.3. Construction Stormwater General Permit Page 12 6. If construction activity extends beyond the certified waiver period for any reason, the operator must either: a. Recalculate the rainfall erosivity “R” factor using the original start date and a new projected ending date and, if the “R” factor is still under 5 and the entire project falls within the applicable regional timeframe in Special Condition S2.C.2.b, complete and submit an amended waiver certification form before the original waiver expires; or b. Submit a complete permit application to Ecology in accordance with Special Condition S2.A and B before the end of the certified waiver period. S3. COMPLIANCE WITH STANDARDS A. Discharges must not cause or contribute to a violation of surface water quality standards (Chapter 173-201A WAC), ground water quality standards (Chapter 173-200 WAC), sediment management standards (Chapter 173-204 WAC), and human health-based criteria in the National Toxics Rule (40 CFR Part 131.36). Discharges not in compliance with these standards are not authorized. B. Prior to the discharge of stormwater and non-stormwater to waters of the State, the Permittee must apply all known, available, and reasonable methods of prevention, control, and treatment (AKART). This includes the preparation and implementation of an adequate SWPPP, with all appropriate BMPs installed and maintained in accordance with the SWPPP and the terms and conditions of this permit. C. Ecology presumes that a Permittee complies with water quality standards unless discharge monitoring data or other site-specific information demonstrates that a discharge causes or contributes to a violation of water quality standards, when the Permittee complies with the following conditions. The Permittee must fully: 1. Comply with all permit conditions, including planning, sampling, monitoring, reporting, and recordkeeping conditions. 2. Implement stormwater BMPs contained in stormwater management manuals published or approved by Ecology, or BMPs that are demonstrably equivalent to BMPs contained in stormwater technical manuals published or approved by Ecology, including the proper selection, implementation, and maintenance of all applicable and appropriate BMPs for on-site pollution control. (For purposes of this section, the stormwater manuals listed in Appendix 10 of the Phase I Municipal Stormwater Permit are approved by Ecology.) D. Where construction sites also discharge to ground water, the ground water discharges must also meet the terms and conditions of this CSWGP. Permittees who discharge to ground water through an injection well must also comply with any applicable requirements of the Underground Injection Control (UIC) regulations, Chapter 173-218 WAC. Construction Stormwater General Permit Page 13 S4. MONITORING REQUIREMENTS, BENCHMARKS, AND REPORTING TRIGGERS A. Site Log Book The Permittee must maintain a site log book that contains a record of the implementation of the SWPPP and other permit requirements, including the installation and maintenance of BMPs, site inspections, and stormwater monitoring. B. Site Inspections The Permittee’s site inspections must include all areas disturbed by construction activities, all BMPs, and all stormwater discharge points under the Permittee’s operational control. (See Special Conditions S4.B.3 and B.4 below for detailed requirements of the Permittee’s Certified Erosion and Sediment Control Lead [CESCL].) Construction sites one acre or larger that discharge stormwater to surface waters of the State must have site inspections conducted by a certified CESCL. Sites less than one acre may have a person without CESCL certification conduct inspections. 1. The Permittee must examine stormwater visually for the presence of suspended sediment, turbidity, discoloration, and oil sheen. The Permittee must evaluate the effectiveness of BMPs and determine if it is necessary to install, maintain, or repair BMPs to improve the quality of stormwater discharges. Based on the results of the inspection, the Permittee must correct the problems identified by: a. Reviewing the SWPPP for compliance with Special Condition S9 and making appropriate revisions within 7 days of the inspection. b. Immediately beginning the process of fully implementing and maintaining appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than within 10 days of the inspection. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Documenting BMP implementation and maintenance in the site log book. 2. The Permittee must inspect all areas disturbed by construction activities, all BMPs, and all stormwater discharge points at least once every calendar week and within 24 hours of any discharge from the site. (For purposes of this condition, individual discharge events that last more than one day do not require daily inspections. For example, if a stormwater pond discharges continuously over the course of a week, only one inspection is required that week.) The Permittee may reduce the inspection frequency for temporarily stabilized, inactive sites to once every calendar month. Construction Stormwater General Permit Page 14 3. The Permittee must have staff knowledgeable in the principles and practices of erosion and sediment control. The CESCL (sites one acre or more) or inspector (sites less than one acre) must have the skills to assess the: a. Site conditions and construction activities that could impact the quality of stormwater, and b. Effectiveness of erosion and sediment control measures used to control the quality of stormwater discharges. 4. The SWPPP must identify the CESCL or inspector, who must be present on site or on-call at all times. The CESCL must obtain this certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology (see BMP C160 in the manual referred to in Special Condition S9.C.1 and 2). 5. The Permittee must summarize the results of each inspection in an inspection report or checklist and enter the report/checklist into, or attach it to, the site log book. At a minimum, each inspection report or checklist must include: a. Inspection date and time. b. Weather information, the general conditions during inspection and the approximate amount of precipitation since the last inspection, and precipitation within the last 24 hours. c. A summary or list of all implemented BMPs, including observations of all erosion/sediment control structures or practices. d. A description of the locations: i. Of BMPs inspected; ii. Of BMPs that need maintenance and why; iii. Of BMPs that failed to operate as designed or intended; and iv. Where additional or different BMPs are needed, and why. e. A description of stormwater discharged from the site. The Permittee must note the presence of suspended sediment, turbidity, discoloration, and oil sheen, as applicable. f. Any water quality monitoring performed during inspection. g. General comments and notes, including a brief description of any BMP repairs, maintenance or installations made following the inspection. h. A summary report and a schedule of implementation of the remedial actions that the Permittee plans to take if the site inspection indicates that the site is out of compliance. The remedial actions taken must meet the requirements of the SWPPP and the permit. Construction Stormwater General Permit Page 15 i. The name, title, and signature of the person conducting the site inspection, a phone number or other reliable method to reach this person, and the following statement: “I certify that this report is true, accurate, and complete to the best of my knowledge and belief.” Table 3: Summary of Primary Monitoring Requirements Size of Soil Disturbance1 Weekly Site Inspections Weekly Sampling w/ Turbidity Meter Weekly Sampling w/ Transparency Tube Weekly pH Sampling2 CESCL Required for Inspections? Sites that disturb less than 1 acre, but are part of a larger Common Plan of Development Required Not Required Not Required Not Required No Sites that disturb 1 acre or more, but fewer than 5 acres Required Sampling Required – either method3 Required Yes Sites that disturb 5 acres or more Required Required Not Required4 Required Yes 1 Soil disturbance is calculated by adding together all areas that will be affected by construction activity. Construction activity means clearing, grading, excavation, and any other activity that disturbs the surface of the land, including ingress/egress from the site. 2 If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work (1,000 cubic yards of poured over the life of a project) or the use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area drains to surface waters of the State or to a storm sewer stormwater collection system that drains to other surface waters of the State, the Permittee must conduct pH sampling in accordance with Special Condition S4.D. 3 Sites with one or more acres, but fewer than 5 acres of soil disturbance, must conduct turbidity or transparency sampling in accordance with Special Condition S4.C. 4 Sites equal to or greater than 5 acres of soil disturbance must conduct turbidity sampling using a turbidity meter in accordance with Special Condition S4.C. Construction Stormwater General Permit Page 16 C. Turbidity/Transparency Sampling Requirements 1. Sampling Methods a. If construction activity involves the disturbance of 5 acres or more, the Permittee must conduct turbidity sampling per Special Condition S4.C. b. If construction activity involves 1 acre or more but fewer than 5 acres of soil disturbance, the Permittee must conduct either transparency sampling or turbidity sampling per Special Condition S4.C. 2. Sampling Frequency a. The Permittee must sample all discharge points at least once every calendar week when stormwater (or authorized non-stormwater) discharges from the site or enters any on-site surface waters of the state (for example, a creek running through a site); sampling is not required on sites that disturb less than an acre. b. Samples must be representative of the flow and characteristics of the discharge. c. Sampling is not required when there is no discharge during a calendar week. d. Sampling is not required outside of normal working hours or during unsafe conditions. e. If the Permittee is unable to sample during a monitoring period, the Permittee must include a brief explanation in the monthly Discharge Monitoring Report (DMR). f. Sampling is not required before construction activity begins. g. The Permittee may reduce the sampling frequency for temporarily stabilized, inactive sites to once every calendar month. 3. Sampling Locations a. Sampling is required at all points where stormwater associated with construction activity (or authorized non-stormwater) is discharged off site, including where it enters any on-site surface waters of the state (for example, a creek running through a site). b. The Permittee may discontinue sampling at discharge points that drain areas of the project that are fully stabilized to prevent erosion. c. The Permittee must identify all sampling point(s) on the SWPPP site map and clearly mark these points in the field with a flag, tape, stake or other visible marker. d. Sampling is not required for discharge that is sent directly to sanitary or combined sewer systems. Construction Stormwater General Permit Page 17 e. The Permittee may discontinue sampling at discharge points in areas of the project where the Permittee no longer has operational control of the construction activity. 4. Sampling and Analysis Methods a. The Permittee performs turbidity analysis with a calibrated turbidity meter (turbidimeter) either on site or at an accredited lab. The Permittee must record the results in the site log book in nephelometric turbidity units (NTUs). b. The Permittee performs transparency analysis on site with a 1¾-inch-diameter, 60-centimeter (cm)-long transparency tube. The Permittee will record the results in the site log book in centimeters (cm). Table 4: Monitoring and Reporting Requirements Parameter Unit Analytical Method Sampling Frequency Benchmark Value Phone Reporting Trigger Value Turbidity NTU SM2130 Weekly, if discharging 25 NTUs 250 NTUs Transparency cm Manufacturer instructions, or Ecology guidance Weekly, if discharging 33 cm 6 cm 5. Turbidity/Transparency Benchmark Values and Reporting Triggers The benchmark value for turbidity is 25 NTUs or less. The benchmark value for transparency is 33 centimeters (cm). Note: Benchmark values do not apply to discharges to segments of water bodies on Washington State’s 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus; these discharges are subject to a numeric effluent limit for turbidity. Refer to Special Condition S8 for more information. a. Turbidity 26 – 249 NTUs, or Transparency 32 – 7 cm: If the discharge turbidity is 26 to 249 NTUs; or if discharge transparency is less than 33 cm, but equal to or greater than 6 cm, the Permittee must: i. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. ii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. Construction Stormwater General Permit Page 18 iii. Document BMP implementation and maintenance in the site log book. b. Turbidity 250 NTUs or greater, or Transparency 6 cm or less: If a discharge point’s turbidity is 250 NTUs or greater, or if discharge transparency is less than or equal to 6 cm, the Permittee must complete the reporting and adaptive management process described below. i. Telephone or submit an electronic report to the applicable Ecology Region’s Environmental Report Tracking System (ERTS) number (or through Ecology’s Water Quality Permitting Portal [WQWebPortal] – Permit Submittals when the form is available) within 24 hours, in accordance with Special Condition S5.A.  Central Region (Okanogan, Chelan, Douglas, Kittitas, Yakima, Klickitat, Benton): (509) 575-2490  Eastern Region (Adams, Asotin, Columbia, Ferry, Franklin, Garfield, Grant, Lincoln, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman): (509) 329-3400  Northwest Region (Kitsap, Snohomish, Island, King, San Juan, Skagit, Whatcom): (425) 649-7000  Southwest Region (Grays Harbor, Lewis, Mason, Thurston, Pierce, Clark, Cowlitz, Skamania, Wahkiakum, Clallam, Jefferson, Pacific): (360) 407-6300 Links to these numbers and the ERTS reporting page are located on the following web site: http://www.ecy.wa.gov/programs/wq/stormwater/construction/index.html. ii. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the date the discharge exceeded the benchmark. iii. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems within 10 days of the date the discharge exceeded the benchmark. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when the Permittee requests an extension within the initial 10-day response period. iv. Document BMP implementation and maintenance in the site log book. v. Sample discharges daily until: a) Turbidity is 25 NTUs (or lower); or b) Transparency is 33 cm (or greater); or Construction Stormwater General Permit Page 19 c) The Permittee has demonstrated compliance with the water quality limit for turbidity: 1) No more than 5 NTUs over background turbidity, if background is less than 50 NTUs, or 2) No more than 10% over background turbidity, if background is 50 NTUs or greater; or d) The discharge stops or is eliminated. D. pH Sampling Requirements – Significant Concrete Work or Engineered Soils If construction activity results in the disturbance of 1 acre or more, and involves significant concrete work (significant concrete work means greater than 1000 cubic yards poured concrete used over the life of a project ) or the use of recycled concrete or engineered soils (soil amendments including but not limited to Portland cement-treated base [CTB], cement kiln dust [CKD], or fly ash), and stormwater from the affected area drains to surface waters of the State or to a storm sewer system that drains to surface waters of the State, the Permittee must conduct pH sampling as set forth below. Note: In addition, discharges to segments of water bodies on Washington State’s 303(d) list (Category 5) for high pH are subject to a numeric effluent limit for pH; refer to Special Condition S8. 1. For sites with significant concrete work, the Permittee must begin the pH sampling period when the concrete is first poured and exposed to precipitation, and continue weekly throughout and after the concrete pour and curing period, until stormwater pH is in the range of 6.5 to 8.5 (su). 2. For sites with recycled concrete, the Permittee must begin the weekly pH sampling period when the recycled concrete is first exposed to precipitation and must continue until the recycled concrete is fully stabilized and stormwater pH is in the range of 6.5 to 8.5 (su). 3. For sites with engineered soils, the Permittee must begin the pH sampling period when the soil amendments are first exposed to precipitation and must continue until the area of engineered soils is fully stabilized. 4. During the applicable pH monitoring period defined above, the Permittee must obtain a representative sample of stormwater and conduct pH analysis at least once per week. 5. The Permittee must sample pH in the sediment trap/pond(s) or other locations that receive stormwater runoff from the area of significant concrete work or engineered soils before the stormwater discharges to surface waters. 6. The benchmark value for pH is 8.5 standard units. Anytime sampling indicates that pH is 8.5 or greater, the Permittee must either: Construction Stormwater General Permit Page 20 a. Prevent the high pH water (8.5 or above) from entering storm sewer systems or surface waters; or b. If necessary, adjust or neutralize the high pH water until it is in the range of pH 6.5 to 8.5 (su) using an appropriate treatment BMP such as carbon dioxide (CO2) sparging or dry ice. The Permittee must obtain written approval from Ecology before using any form of chemical treatment other than CO2 sparging or dry ice. 7. The Permittee must perform pH analysis on site with a calibrated pH meter, pH test kit, or wide range pH indicator paper. The Permittee must record pH sampling results in the site log book. S5. REPORTING AND RECORDKEEPING REQUIREMENTS A. High Turbidity Reporting Anytime sampling performed in accordance with Special Condition S4.C indicates turbidity has reached the 250 NTUs or more (or transparency less than or equal to 6 cm) high turbidity reporting level, the Permittee must either call the applicable Ecology Region’s Environmental Report Tracking System (ERTS) number by phone within 24 hours of analysis or submit an electronic ERTS report (or submit an electronic report through Ecology’s Water Quality Permitting Portal (WQWebPortal) – Permit Submittals when the form is available). See the CSWGP web site for links to ERTS and the WQWebPortal: http://www.ecy.wa.gov/programs/wq/stormwater/construction/ index.html. Also, see phone numbers in Special Condition S4.C.5.b.i. B. Discharge Monitoring Reports (DMRs) Permittees required to conduct water quality sampling in accordance with Special Conditions S4.C (Turbidity/Transparency), S4.D (pH), S8 (303[d]/TMDL sampling), and/or G13 (Additional Sampling) must submit the results to Ecology. Permittees must submit monitoring data using Ecology's WQWebDMR web application accessed through Ecology’s Water Quality Permitting Portal. To find out more information and to sign up for WQWebDMR go to: http://www.ecy.wa.gov/programs/ wq/permits/paris/portal.html. Permittees unable to submit electronically (for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper copy DMR at: Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Permittees who obtain a waiver not to use WQWebDMR must use the forms provided to them by Ecology; submittals must be mailed to the address above. Permittees shall Construction Stormwater General Permit Page 21 submit DMR forms to be received by Ecology within 15 days following the end of each month. If there was no discharge during a given monitoring period, all Permittees must submit a DMR as required with “no discharge" entered in place of the monitoring results. DMRs are required for the full duration of permit coverage (from issuance date to termination). For more information, contact Ecology staff using information provided at the following web site: www.ecy.wa.gov/programs/wq/permits/paris/contacts.html. C. Records Retention The Permittee must retain records of all monitoring information (site log book, sampling results, inspection reports/checklists, etc.), Stormwater Pollution Prevention Plan, copy of the permit coverage letter (including Transfer of Coverage documentation), and any other documentation of compliance with permit requirements for the entire life of the construction project and for a minimum of three years following the termination of permit coverage. Such information must include all calibration and maintenance records, and records of all data used to complete the application for this permit. This period of retention must be extended during the course of any unresolved litigation regarding the discharge of pollutants by the Permittee or when requested by Ecology. D. Recording Results For each measurement or sample taken, the Permittee must record the following information: 1. Date, place, method, and time of sampling or measurement. 2. The first and last name of the individual who performed the sampling or measurement. 3. The date(s) the analyses were performed. 4. The first and last name of the individual who performed the analyses. 5. The analytical techniques or methods used. 6. The results of all analyses. E. Additional Monitoring by the Permittee If the Permittee monitors any pollutant more frequently than required by this permit using test procedures specified by Special Condition S4 of this permit, the results of this monitoring must be included in the calculation and reporting of the data submitted in the Permittee’s DMR. F. Noncompliance Notification In the event the Permittee is unable to comply with any part of the terms and conditions of this permit, and the resulting noncompliance may cause a threat to human health or the environment (such as but not limited to spills of fuels or other materials, catastrophic pond or slope failure, and discharges that violate water quality standards), or exceed Construction Stormwater General Permit Page 22 numeric effluent limitations (see S8. Discharges to 303(d) or TMDL Waterbodies), the Permittee must, upon becoming aware of the circumstance: 1. Notify Ecology within 24-hours of the failure to comply by calling the applicable Regional office ERTS phone number (refer to Special Condition S4.C.5.b.i. or www.ecy.wa.gov/programs/wq/stormwater/construction/turbidity.html for Regional ERTS phone numbers). 2. Immediately take action to prevent the discharge/pollution, or otherwise stop or correct the noncompliance, and, if applicable, repeat sampling and analysis of any noncompliance immediately and submit the results to Ecology within five (5) days of becoming aware of the violation. 3. Submit a detailed written report to Ecology within five (5) days, of the time the Permittee becomes aware of the circumstances, unless requested earlier by Ecology. The report must be submitted using Ecology’s Water Quality Permitting Portal (WQWebPortal) - Permit Submittals, unless a waiver from electronic reporting has been granted according to S5.B. The report must contain a description of the noncompliance, including exact dates and times, and if the noncompliance has not been corrected, the anticipated time it is expected to continue; and the steps taken or planned to reduce, eliminate, and prevent reoccurrence of the noncompliance. The Permittee must report any unanticipated bypass and/or upset that exceeds any effluent limit in the permit in accordance with the 24-hour reporting requirement contained in 40 C.F.R. 122.41(l)(6). Compliance with these requirements does not relieve the Permittee from responsibility to maintain continuous compliance with the terms and conditions of this permit or the resulting liability for failure to comply. Upon request of the Permittee, Ecology may waive the requirement for a written report on a case-by- case basis, if the immediate notification is received by Ecology within 24 hours. G. Access to Plans and Records 1. The Permittee must retain the following permit documentation (plans and records) on site, or within reasonable access to the site, for use by the operator or for on-site review by Ecology or the local jurisdiction: a. General Permit b. Permit Coverage Letter c. Stormwater Pollution Prevention Plan (SWPPP) d. Site Log Book 2. The Permittee must address written requests for plans and records listed above (Special Condition S5.G.1) as follows: Construction Stormwater General Permit Page 23 a. The Permittee must provide a copy of plans and records to Ecology within 14 days of receipt of a written request from Ecology. b. The Permittee must provide a copy of plans and records to the public when requested in writing. Upon receiving a written request from the public for the Permittee’s plans and records, the Permittee must either: i. Provide a copy of the plans and records to the requester within 14 days of a receipt of the written request; or ii. Notify the requester within 10 days of receipt of the written request of the location and times within normal business hours when the plans and records may be viewed; and provide access to the plans and records within 14 days of receipt of the written request; or iii. Within 14 days of receipt of the written request, the Permittee may submit a copy of the plans and records to Ecology for viewing and/or copying by the requester at an Ecology office, or a mutually agreed location. If plans and records are viewed and/or copied at a location other than at an Ecology office, the Permittee will provide reasonable access to copying services for which a reasonable fee may be charged. The Permittee must notify the requester within 10 days of receipt of the request where the plans and records may be viewed and/or copied. S6. PERMIT FEES The Permittee must pay permit fees assessed by Ecology. Fees for stormwater discharges covered under this permit are established by Chapter 173-224 WAC. Ecology continues to assess permit fees until the permit is terminated in accordance with Special Condition S10 or revoked in accordance with General Condition G5. S7. SOLID AND LIQUID WASTE DISPOSAL The Permittee must handle and dispose of solid and liquid wastes generated by construction activity, such as demolition debris, construction materials, contaminated materials, and waste materials from maintenance activities, including liquids and solids from cleaning catch basins and other stormwater facilities, in accordance with: A. Special Condition S3, Compliance with Standards B. WAC 173-216-110 C. Other applicable regulations S8. DISCHARGES TO 303(d) OR TMDL WATERBODIES A. Sampling and Numeric Effluent Limits For Certain Discharges to 303(d)-listed Waterbodies Construction Stormwater General Permit Page 24 1. Permittees who discharge to segments of waterbodies listed as impaired by the State of Washington under Section 303(d) of the Clean Water Act for turbidity, fine sediment, high pH, or phosphorus, must conduct water quality sampling according to the requirements of this section, and Special Conditions S4.C.2.b-f and S4.C.3.b-d, and must comply with the applicable numeric effluent limitations in S8.C and S8.D. 2. All references and requirements associated with Section 303(d) of the Clean Water Act mean the most current listing by Ecology of impaired waters (Category 5) that exists on January 1, 2016, or the date when the operator’s complete permit application is received by Ecology, whichever is later. B. Limits on Coverage for New Discharges to TMDL or 303(d)-listed Waters Operators of construction sites that discharge to a TMDL or 303(d)-listed waterbody are not eligible for coverage under this permit unless the operator: 1. Prevents exposing stormwater to pollutants for which the waterbody is impaired, and retains documentation in the SWPPP that details procedures taken to prevent exposure on site; or 2. Documents that the pollutants for which the waterbody is impaired are not present at the site, and retains documentation of this finding within the SWPPP; or 3. Provides Ecology with data indicating the discharge is not expected to cause or contribute to an exceedance of a water quality standard, and retains such data on site with the SWPPP. The operator must provide data and other technical information to Ecology that sufficiently demonstrate: a. For discharges to waters without an EPA-approved or -established TMDL, that the discharge of the pollutant for which the water is impaired will meet in- stream water quality criteria at the point of discharge to the waterbody; or b. For discharges to waters with an EPA-approved or -established TMDL, that there is sufficient remaining wasteload allocation in the TMDL to allow construction stormwater discharge and that existing dischargers to the waterbody are subject to compliance schedules designed to bring the waterbody into attainment with water quality standards. Operators of construction sites are eligible for coverage under this permit if Ecology issues permit coverage based upon an affirmative determination that the discharge will not cause or contribute to the existing impairment. C. Sampling and Numeric Effluent Limits for Discharges to Water Bodies on the 303(d) List for Turbidity, Fine Sediment, or Phosphorus 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for turbidity, fine sediment, or phosphorus must conduct turbidity sampling in accordance with Special Condition S4.C.2 and comply with either of the numeric effluent limits noted in Table 5 below. Construction Stormwater General Permit Page 25 2. As an alternative to the 25 NTUs effluent limit noted in Table 5 below (applied at the point where stormwater [or authorized non-stormwater] is discharged off-site), Permittees may choose to comply with the surface water quality standard for turbidity. The standard is: no more than 5 NTUs over background turbidity when the background turbidity is 50 NTUs or less, or no more than a 10% increase in turbidity when the background turbidity is more than 50 NTUs. In order to use the water quality standard requirement, the sampling must take place at the following locations: a. Background turbidity in the 303(d)-listed receiving water immediately upstream (upgradient) or outside the area of influence of the discharge. b. Turbidity at the point of discharge into the 303(d)-listed receiving water, inside the area of influence of the discharge. 3. Discharges that exceed the numeric effluent limit for turbidity constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit shall sample discharges daily until the violation is corrected and comply with the non- compliance notification requirements in Special Condition S5.F. Table 5: Turbidity, Fine Sediment & Phosphorus Sampling and Limits for 303(d)-Listed Waters Parameter identified in 303(d) listing Parameter Sampled Unit Analytical Method Sampling Frequency Numeric Effluent Limit1  Turbidity  Fine Sediment  Phosphorus Turbidity NTU SM2130 Weekly, if discharging 25 NTUs, at the point where stormwater is discharged from the site; OR In compliance with the surface water quality standard for turbidity (S8.C.2.a) 1Permittees subject to a numeric effluent limit for turbidity may, at their discretion, choose either numeric effluent limitation based on site-specific considerations including, but not limited to, safety, access and convenience. D. Discharges to Water Bodies on the 303(d) List for High pH 1. Permittees who discharge to segments of water bodies on the 303(d) list (Category 5) for high pH must conduct pH sampling in accordance with the table below, and comply with the numeric effluent limit of pH 6.5 to 8.5 su (Table 6). Construction Stormwater General Permit Page 26 Table 6: pH Sampling and Limits for 303(d)-Listed Waters Parameter identified in 303(d) listing Parameter Sampled/Units Analytical Method Sampling Frequency Numeric Effluent Limit High pH pH /Standard Units pH meter Weekly, if discharging In the range of 6.5 – 8.5 2. At the Permittee’s discretion, compliance with the limit shall be assessed at one of the following locations: a. Directly in the 303(d)-listed waterbody segment, inside the immediate area of influence of the discharge; or b. Alternatively, the Permittee may measure pH at the point where the discharge leaves the construction site, rather than in the receiving water. 3. Discharges that exceed the numeric effluent limit for pH (outside the range of 6.5 – 8.5 su) constitute a violation of this permit. 4. Permittees whose discharges exceed the numeric effluent limit shall sample discharges daily until the violation is corrected and comply with the non- compliance notification requirements in Special Condition S5.F. E. Sampling and Limits for Sites Discharging to Waters Covered by a TMDL or Another Pollution Control Plan 1. Discharges to a waterbody that is subject to a Total Maximum Daily Load (TMDL) for turbidity, fine sediment, high pH, or phosphorus must be consistent with the TMDL. Refer to http://www.ecy.wa.gov/programs/wq/tmdl/ TMDLsbyWria/TMDLbyWria.html for more information on TMDLs. a. Where an applicable TMDL sets specific waste load allocations or requirements for discharges covered by this permit, discharges must be consistent with any specific waste load allocations or requirements established by the applicable TMDL. i. The Permittee must sample discharges weekly or as otherwise specified by the TMDL to evaluate compliance with the specific waste load allocations or requirements. ii. Analytical methods used to meet the monitoring requirements must conform to the latest revision of the Guidelines Establishing Test Procedures for the Analysis of Pollutants contained in 40 CFR Part 136. Turbidity and pH methods need not be accredited or registered unless conducted at a laboratory which must otherwise be accredited or registered. b. Where an applicable TMDL has established a general waste load allocation for construction stormwater discharges, but has not identified specific requirements, Construction Stormwater General Permit Page 27 compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. c. Where an applicable TMDL has not specified a waste load allocation for construction stormwater discharges, but has not excluded these discharges, compliance with Special Conditions S4 (Monitoring) and S9 (SWPPPs) will constitute compliance with the approved TMDL. d. Where an applicable TMDL specifically precludes or prohibits discharges from construction activity, the operator is not eligible for coverage under this permit. 2. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus that is completed and approved by EPA before January 1, 2016, or before the date the operator’s complete permit application is received by Ecology, whichever is later. TMDLs completed after the operator’s complete permit application is received by Ecology become applicable to the Permittee only if they are imposed through an administrative order by Ecology, or through a modification of permit coverage. S9. STORMWATER POLLUTION PREVENTION PLAN The Permittee must prepare and properly implement an adequate Stormwater Pollution Prevention Plan (SWPPP) for construction activity in accordance with the requirements of this permit beginning with initial soil disturbance and until final stabilization. A. The Permittee’s SWPPP must meet the following objectives: 1. To implement best management practices (BMPs) to prevent erosion and sedimentation, and to identify, reduce, eliminate or prevent stormwater contamination and water pollution from construction activity. 2. To prevent violations of surface water quality, ground water quality, or sediment management standards. 3. To control peak volumetric flow rates and velocities of stormwater discharges. B. General Requirements 1. The SWPPP must include a narrative and drawings. All BMPs must be clearly referenced in the narrative and marked on the drawings. The SWPPP narrative must include documentation to explain and justify the pollution prevention decisions made for the project. Documentation must include: a. Information about existing site conditions (topography, drainage, soils, vegetation, etc.). b. Potential erosion problem areas. c. The 13 elements of a SWPPP in Special Condition S9.D.1-13, including BMPs used to address each element. Construction Stormwater General Permit Page 28 d. Construction phasing/sequence and general BMP implementation schedule. e. The actions to be taken if BMP performance goals are not achieved—for example, a contingency plan for additional treatment and/or storage of stormwater that would violate the water quality standards if discharged. f. Engineering calculations for ponds, treatment systems, and any other designed structures. 2. The Permittee must modify the SWPPP if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is, or would be, ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The Permittee must then: a. Review the SWPPP for compliance with Special Condition S9 and make appropriate revisions within 7 days of the inspection or investigation. b. Immediately begin the process to fully implement and maintain appropriate source control and/or treatment BMPs as soon as possible, addressing the problems no later than 10 days from the inspection or investigation. If installation of necessary treatment BMPs is not feasible within 10 days, Ecology may approve additional time when an extension is requested by a Permittee within the initial 10-day response period. c. Document BMP implementation and maintenance in the site log book. The Permittee must modify the SWPPP whenever there is a change in design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the State. C. Stormwater Best Management Practices (BMPs) BMPs must be consistent with: 1. Stormwater Management Manual for Western Washington (most current approved edition at the time this permit was issued), for sites west of the crest of the Cascade Mountains; or 2. Stormwater Management Manual for Eastern Washington (most current approved edition at the time this permit was issued), for sites east of the crest of the Cascade Mountains; or 3. Revisions to the manuals listed in Special Condition S9.C.1. & 2., or other stormwater management guidance documents or manuals which provide an equivalent level of pollution prevention, that are approved by Ecology and incorporated into this permit in accordance with the permit modification requirements of WAC 173-226-230; or Construction Stormwater General Permit Page 29 4. Documentation in the SWPPP that the BMPs selected provide an equivalent level of pollution prevention, compared to the applicable Stormwater Management Manuals, including: a. The technical basis for the selection of all stormwater BMPs (scientific, technical studies, and/or modeling) that support the performance claims for the BMPs being selected. b. An assessment of how the selected BMP will satisfy AKART requirements and the applicable federal technology-based treatment requirements under 40 CFR part 125.3. D. SWPPP – Narrative Contents and Requirements The Permittee must include each of the 13 elements below in Special Condition S9.D.1-13 in the narrative of the SWPPP and implement them unless site conditions render the element unnecessary and the exemption from that element is clearly justified in the SWPPP. 1. Preserve Vegetation/Mark Clearing Limits a. Before beginning land-disturbing activities, including clearing and grading, clearly mark all clearing limits, sensitive areas and their buffers, and trees that are to be preserved within the construction area. b. Retain the duff layer, native topsoil, and natural vegetation in an undisturbed state to the maximum degree practicable. 2. Establish Construction Access a. Limit construction vehicle access and exit to one route, if possible. b. Stabilize access points with a pad of quarry spalls, crushed rock, or other equivalent BMPs, to minimize tracking sediment onto roads. c. Locate wheel wash or tire baths on site, if the stabilized construction entrance is not effective in preventing tracking sediment onto roads. d. If sediment is tracked off site, clean the affected roadway thoroughly at the end of each day, or more frequently as necessary (for example, during wet weather). Remove sediment from roads by shoveling, sweeping, or pickup and transport of the sediment to a controlled sediment disposal area. e. Conduct street washing only after sediment removal in accordance with Special Condition S9.D.2.d. Control street wash wastewater by pumping back on site or otherwise preventing it from discharging into systems tributary to waters of the State. 3. Control Flow Rates a. Protect properties and waterways downstream of development sites from erosion and the associated discharge of turbid waters due to increases in the Construction Stormwater General Permit Page 30 velocity and peak volumetric flow rate of stormwater runoff from the project site, as required by local plan approval authority. b. Where necessary to comply with Special Condition S9.D.3.a, construct stormwater retention or detention facilities as one of the first steps in grading. Assure that detention facilities function properly before constructing site improvements (for example, impervious surfaces). c. If permanent infiltration ponds are used for flow control during construction, protect these facilities from siltation during the construction phase. 4. Install Sediment Controls The Permittee must design, install and maintain effective erosion controls and sediment controls to minimize the discharge of pollutants. At a minimum, the Permittee must design, install and maintain such controls to: a. Construct sediment control BMPs (sediment ponds, traps, filters, infiltration facilities, etc.) as one of the first steps in grading. These BMPs must be functional before other land disturbing activities take place. b. Minimize sediment discharges from the site. The design, installation and maintenance of erosion and sediment controls must address factors such as the amount, frequency, intensity and duration of precipitation, the nature of resulting stormwater runoff, and soil characteristics, including the range of soil particle sizes expected to be present on the site. c. Direct stormwater runoff from disturbed areas through a sediment pond or other appropriate sediment removal BMP, before the runoff leaves a construction site or before discharge to an infiltration facility. Runoff from fully stabilized areas may be discharged without a sediment removal BMP, but must meet the flow control performance standard of Special Condition S9.D.3.a. d. Locate BMPs intended to trap sediment on site in a manner to avoid interference with the movement of juvenile salmonids attempting to enter off-channel areas or drainages. e. Provide and maintain natural buffers around surface waters, direct stormwater to vegetated areas to increase sediment removal and maximize stormwater infiltration, unless infeasible. f. Where feasible, design outlet structures that withdraw impounded stormwater from the surface to avoid discharging sediment that is still suspended lower in the water column. 5. Stabilize Soils a. The Permittee must stabilize exposed and unworked soils by application of effective BMPs that prevent erosion. Applicable BMPs include, but are not limited to: temporary and permanent seeding, sodding, mulching, plastic covering, erosion control fabrics and matting, soil application of polyacrylamide Construction Stormwater General Permit Page 31 (PAM), the early application of gravel base on areas to be paved, and dust control. b. The Permittee must control stormwater volume and velocity within the site to minimize soil erosion. c. The Permittee must control stormwater discharges, including both peak flow rates and total stormwater volume, to minimize erosion at outlets and to minimize downstream channel and stream bank erosion. d. Depending on the geographic location of the project, the Permittee must not allow soils to remain exposed and unworked for more than the time periods set forth below to prevent erosion: West of the Cascade Mountains Crest During the dry season (May 1 - September 30): 7 days During the wet season (October 1 - April 30): 2 days East of the Cascade Mountains Crest, except for Central Basin* During the dry season (July 1 - September 30): 10 days During the wet season (October 1 - June 30): 5 days The Central Basin*, East of the Cascade Mountains Crest During the dry season (July 1 - September 30): 30 days During the wet season (October 1 - June 30): 15 days *Note: The Central Basin is defined as the portions of Eastern Washington with mean annual precipitation of less than 12 inches. e. The Permittee must stabilize soils at the end of the shift before a holiday or weekend if needed based on the weather forecast. f. The Permittee must stabilize soil stockpiles from erosion, protected with sediment trapping measures, and where possible, be located away from storm drain inlets, waterways, and drainage channels. g. The Permittee must minimize the amount of soil exposed during construction activity. h. The Permittee must minimize the disturbance of steep slopes. i. The Permittee must minimize soil compaction and, unless infeasible, preserve topsoil. 6. Protect Slopes a. The Permittee must design and construct cut-and-fill slopes in a manner to minimize erosion. Applicable practices include, but are not limited to, reducing continuous length of slope with terracing and diversions, reducing slope steepness, and roughening slope surfaces (for example, track walking). Construction Stormwater General Permit Page 32 b. The Permittee must divert off-site stormwater (run-on) or ground water away from slopes and disturbed areas with interceptor dikes, pipes, and/or swales. Off-site stormwater should be managed separately from stormwater generated on the site. c. At the top of slopes, collect drainage in pipe slope drains or protected channels to prevent erosion. i. West of the Cascade Mountains Crest: Temporary pipe slope drains must handle the peak 10-minute flow rate from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate predicted by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the Western Washington Hydrology Model (WWHM) to predict flows, bare soil areas should be modeled as "landscaped area.” ii. East of the Cascade Mountains Crest: Temporary pipe slope drains must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. d. Place excavated material on the uphill side of trenches, consistent with safety and space considerations. e. Place check dams at regular intervals within constructed channels that are cut down a slope. 7. Protect Drain Inlets a. Protect all storm drain inlets made operable during construction so that stormwater runoff does not enter the conveyance system without first being filtered or treated to remove sediment. b. Clean or remove and replace inlet protection devices when sediment has filled one-third of the available storage (unless a different standard is specified by the product manufacturer). 8. Stabilize Channels and Outlets a. Design, construct and stabilize all on-site conveyance channels to prevent erosion from the following expected peak flows: i. West of the Cascade Mountains Crest: Channels must handle the peak 10-minute flow rate from a Type 1A, 10-year, 24-hour frequency storm for the developed condition. Alternatively, the 10-year, 1-hour flow rate indicated by an approved continuous runoff model, increased by a factor of 1.6, may be used. The hydrologic analysis must use the existing land Construction Stormwater General Permit Page 33 cover condition for predicting flow rates from tributary areas outside the project limits. For tributary areas on the project site, the analysis must use the temporary or permanent project land cover condition, whichever will produce the highest flow rates. If using the WWHM to predict flows, bare soil areas should be modeled as "landscaped area.” ii. East of the Cascade Mountains Crest: Channels must handle the expected peak flow rate from a 6-month, 3-hour storm for the developed condition, referred to as the short duration storm. b. Provide stabilization, including armoring material, adequate to prevent erosion of outlets, adjacent stream banks, slopes, and downstream reaches at the outlets of all conveyance systems. 9. Control Pollutants Design, install, implement and maintain effective pollution prevention measures to minimize the discharge of pollutants. The Permittee must: a. Handle and dispose of all pollutants, including waste materials and demolition debris that occur on site in a manner that does not cause contamination of stormwater. b. Provide cover, containment, and protection from vandalism for all chemicals, liquid products, petroleum products, and other materials that have the potential to pose a threat to human health or the environment. On-site fueling tanks must include secondary containment. Secondary containment means placing tanks or containers within an impervious structure capable of containing 110% of the volume contained in the largest tank within the containment structure. Double- walled tanks do not require additional secondary containment. c. Conduct maintenance, fueling, and repair of heavy equipment and vehicles using spill prevention and control measures. Clean contaminated surfaces immediately following any spill incident. d. Discharge wheel wash or tire bath wastewater to a separate on-site treatment system that prevents discharge to surface water, such as closed-loop recirculation or upland land application, or to the sanitary sewer with local sewer district approval. e. Apply fertilizers and pesticides in a manner and at application rates that will not result in loss of chemical to stormwater runoff. Follow manufacturers’ label requirements for application rates and procedures. f. Use BMPs to prevent contamination of stormwater runoff by pH-modifying sources. The sources for this contamination include, but are not limited to: bulk cement, cement kiln dust, fly ash, new concrete washing and curing waters, recycled concrete stockpiles, waste streams generated from concrete grinding and sawing, exposed aggregate processes, dewatering concrete vaults, concrete Construction Stormwater General Permit Page 34 pumping and mixer washout waters. (Also refer to the definition for "concrete wastewater" in Appendix A--Definitions.) g. Adjust the pH of stormwater or authorized non-stormwater if necessary to prevent an exceedance of groundwater and/or surface water quality standards. h. Assure that washout of concrete trucks is performed off-site or in designated concrete washout areas only. Do not wash out concrete trucks or concrete handling equipment onto the ground, or into storm drains, open ditches, streets, or streams. Do not dump excess concrete on site, except in designated concrete washout areas. Concrete spillage or concrete discharge to surface waters of the State is prohibited. i. Obtain written approval from Ecology before using any chemical treatment, with the exception of CO2 or dry ice used to adjust pH. j. Uncontaminated water from water-only based shaft drilling for construction of building, road, and bridge foundations may be infiltrated provided the wastewater is managed in a way that prohibits discharge to surface waters. Prior to infiltration, water from water-only based shaft drilling that comes into contact with curing concrete must be neutralized until pH is in the range of 6.5 to 8.5 (su). 10. Control Dewatering a. Permittees must discharge foundation, vault, and trench dewatering water, which have characteristics similar to stormwater runoff at the site, into a controlled conveyance system before discharge to a sediment trap or sediment pond. b. Permittees may discharge clean, non-turbid dewatering water, such as well- point ground water, to systems tributary to, or directly into surface waters of the State, as specified in Special Condition S9.D.8, provided the dewatering flow does not cause erosion or flooding of receiving waters. Do not route clean dewatering water through stormwater sediment ponds. Note that “surface waters of the State” may exist on a construction site as well as off site; for example, a creek running through a site. c. Other dewatering treatment or disposal options may include: i. Infiltration. ii. Transport off site in a vehicle, such as a vacuum flush truck, for legal disposal in a manner that does not pollute state waters. iii. Ecology-approved on-site chemical treatment or other suitable treatment technologies (see S9.D.9.i. regarding chemical treatment written approval). iv. Sanitary or combined sewer discharge with local sewer district approval, if there is no other option. Construction Stormwater General Permit Page 35 v. Use of a sedimentation bag with discharge to a ditch or swale for small volumes of localized dewatering. d. Permittees must handle highly turbid or contaminated dewatering water separately from stormwater. 11. Maintain BMPs a. Permittees must maintain and repair all temporary and permanent erosion and sediment control BMPs as needed to assure continued performance of their intended function in accordance with BMP specifications. b. Permittees must remove all temporary erosion and sediment control BMPs within 30 days after achieving final site stabilization or after the temporary BMPs are no longer needed. 12. Manage the Project a. Phase development projects to the maximum degree practicable and take into account seasonal work limitations. b. Inspection and monitoring – Inspect, maintain and repair all BMPs as needed to assure continued performance of their intended function. Conduct site inspections and monitoring in accordance with Special Condition S4. c. Maintaining an updated construction SWPPP – Maintain, update, and implement the SWPPP in accordance with Special Conditions S3, S4 and S9. 13. Protect Low Impact Development (LID) BMPs The primary purpose of LID BMPs/On-site LID Stormwater Management BMPs is to reduce the disruption of the natural site hydrology. LID BMPs are permanent facilities. a. Permittees must protect all Bioretention and Rain Garden facilities from sedimentation through installation and maintenance of erosion and sediment control BMPs on portions of the site that drain into the Bioretention and/or Rain Garden facilities. Restore the facilities to their fully functioning condition if they accumulate sediment during construction. Restoring the facility must include removal of sediment and any sediment-laden Bioretention/Rain Garden soils, and replacing the removed soils with soils meeting the design specification. b. Permittees must maintain the infiltration capabilities of Bioretention and Rain Garden facilities by protecting against compaction by construction equipment and foot traffic. Protect completed lawn and landscaped areas from compaction due to construction equipment. c. Permittees must control erosion and avoid introducing sediment from surrounding land uses onto permeable pavements. Do not allow muddy Construction Stormwater General Permit Page 36 construction equipment on the base material or pavement. Do not allow sediment-laden runoff onto permeable pavements. d. Permittees must clean permeable pavements fouled with sediments or no longer passing an initial infiltration test using local stormwater manual methodology or the manufacturer’s procedures. e. Permittees must keep all heavy equipment off existing soils under LID facilities that have been excavated to final grade to retain the infiltration rate of the soils. E. SWPPP – Map Contents and Requirements The Permittee’s SWPPP must also include a vicinity map or general location map (for example, a USGS quadrangle map, a portion of a county or city map, or other appropriate map) with enough detail to identify the location of the construction site and receiving waters within one mile of the site. The SWPPP must also include a legible site map (or maps) showing the entire construction site. The following features must be identified, unless not applicable due to site conditions: 1. The direction of north, property lines, and existing structures and roads. 2. Cut and fill slopes indicating the top and bottom of slope catch lines. 3. Approximate slopes, contours, and direction of stormwater flow before and after major grading activities. 4. Areas of soil disturbance and areas that will not be disturbed. 5. Locations of structural and nonstructural controls (BMPs) identified in the SWPPP. 6. Locations of off-site material, stockpiles, waste storage, borrow areas, and vehicle/equipment storage areas. 7. Locations of all surface water bodies, including wetlands. 8. Locations where stormwater or non-stormwater discharges off-site and/or to a surface waterbody, including wetlands. 9. Location of water quality sampling station(s), if sampling is required by state or local permitting authority. 10. Areas where final stabilization has been accomplished and no further construction- phase permit requirements apply. 11. Location or proposed location of LID facilities. Construction Stormwater General Permit Page 37 S10. NOTICE OF TERMINATION A. The site is eligible for termination of coverage when it has met any of the following conditions: 1. The site has undergone final stabilization, the Permittee has removed all temporary BMPs (except biodegradable BMPs clearly manufactured with the intention for the material to be left in place and not interfere with maintenance or land use), and all stormwater discharges associated with construction activity have been eliminated; or 2. All portions of the site that have not undergone final stabilization per Special Condition S10.A.1 have been sold and/or transferred (per General Condition G9), and the Permittee no longer has operational control of the construction activity; or 3. For residential construction only, the Permittee has completed temporary stabilization and the homeowners have taken possession of the residences. B. When the site is eligible for termination, the Permittee must submit a complete and accurate Notice of Termination (NOT) form, signed in accordance with General Condition G2, to: Department of Ecology Water Quality Program – Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 When an electronic termination form is available, the Permittee may choose to submit a complete and accurate Notice of Termination (NOT) form through the Water Quality Permitting Portal rather than mailing a hardcopy as noted above. The termination is effective on the thirty-first calendar day following the date Ecology receives a complete NOT form, unless Ecology notifies the Permittee that the termination request is denied because the Permittee has not met the eligibility requirements in Special Condition S10.A. Permittees are required to comply with all conditions and effluent limitations in the permit until the permit has been terminated. Permittees transferring the property to a new property owner or operator/Permittee are required to complete and submit the Notice of Transfer form to Ecology, but are not required to submit a Notice of Termination form for this type of transaction. Construction Stormwater General Permit Page 38 GENERAL CONDITIONS G1. DISCHARGE VIOLATIONS All discharges and activities authorized by this general permit must be consistent with the terms and conditions of this general permit. Any discharge of any pollutant more frequent than or at a level in excess of that identified and authorized by the general permit must constitute a violation of the terms and conditions of this permit. G2. SIGNATORY REQUIREMENTS A. All permit applications must bear a certification of correctness to be signed: 1. In the case of corporations, by a responsible corporate officer; 2. In the case of a partnership, by a general partner of a partnership; 3. In the case of sole proprietorship, by the proprietor; or 4. In the case of a municipal, state, or other public facility, by either a principal executive officer or ranking elected official. B. All reports required by this permit and other information requested by Ecology (including NOIs, NOTs, and Transfer of Coverage forms) must be signed by a person described above or by a duly authorized representative of that person. A person is a duly authorized representative only if: 1. The authorization is made in writing by a person described above and submitted to Ecology. 2. The authorization specifies either an individual or a position having responsibility for the overall operation of the regulated facility, such as the position of plant manager, superintendent, position of equivalent responsibility, or an individual or position having overall responsibility for environmental matters. C. Changes to authorization. If an authorization under paragraph G2.B.2 above is no longer accurate because a different individual or position has responsibility for the overall operation of the facility, a new authorization satisfying the requirements of paragraph G2.B.2 above must be submitted to Ecology prior to or together with any reports, information, or applications to be signed by an authorized representative. D. Certification. Any person signing a document under this section must make the following certification: “I certify under penalty of law, that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering information, the information submitted is, to the best of my Construction Stormwater General Permit Page 39 knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations.” G3. RIGHT OF INSPECTION AND ENTRY The Permittee must allow an authorized representative of Ecology, upon the presentation of credentials and such other documents as may be required by law: A. To enter upon the premises where a discharge is located or where any records are kept under the terms and conditions of this permit. B. To have access to and copy – at reasonable times and at reasonable cost – any records required to be kept under the terms and conditions of this permit. C. To inspect – at reasonable times – any facilities, equipment (including monitoring and control equipment), practices, methods, or operations regulated or required under this permit. D. To sample or monitor – at reasonable times – any substances or parameters at any location for purposes of assuring permit compliance or as otherwise authorized by the Clean Water Act. G4. GENERAL PERMIT MODIFICATION AND REVOCATION This permit may be modified, revoked and reissued, or terminated in accordance with the provisions of Chapter 173-226 WAC. Grounds for modification, revocation and reissuance, or termination include, but are not limited to, the following: A. When a change occurs in the technology or practices for control or abatement of pollutants applicable to the category of dischargers covered under this permit. B. When effluent limitation guidelines or standards are promulgated pursuant to the CWA or Chapter 90.48 RCW, for the category of dischargers covered under this permit. C. When a water quality management plan containing requirements applicable to the category of dischargers covered under this permit is approved, or D. When information is obtained that indicates cumulative effects on the environment from dischargers covered under this permit are unacceptable. G5. REVOCATION OF COVERAGE UNDER THE PERMIT Pursuant to Chapter 43.21B RCW and Chapter 173-226 WAC, the Director may terminate coverage for any discharger under this permit for cause. Cases where coverage may be terminated include, but are not limited to, the following: A. Violation of any term or condition of this permit. B. Obtaining coverage under this permit by misrepresentation or failure to disclose fully all relevant facts. Construction Stormwater General Permit Page 40 C. A change in any condition that requires either a temporary or permanent reduction or elimination of the permitted discharge. D. Failure or refusal of the Permittee to allow entry as required in RCW 90.48.090. E. A determination that the permitted activity endangers human health or the environment, or contributes to water quality standards violations. F. Nonpayment of permit fees or penalties assessed pursuant to RCW 90.48.465 and Chapter 173-224 WAC. G. Failure of the Permittee to satisfy the public notice requirements of WAC 173-226- 130(5), when applicable. The Director may require any discharger under this permit to apply for and obtain coverage under an individual permit or another more specific general permit. Permittees who have their coverage revoked for cause according to WAC 173-226-240 may request temporary coverage under this permit during the time an individual permit is being developed, provided the request is made within ninety (90) days from the time of revocation and is submitted along with a complete individual permit application form. G6. REPORTING A CAUSE FOR MODIFICATION The Permittee must submit a new application, or a supplement to the previous application, whenever a material change to the construction activity or in the quantity or type of discharge is anticipated which is not specifically authorized by this permit. This application must be submitted at least sixty (60) days prior to any proposed changes. Filing a request for a permit modification, revocation and reissuance, or termination, or a notification of planned changes or anticipated noncompliance does not relieve the Permittee of the duty to comply with the existing permit until it is modified or reissued. G7. COMPLIANCE WITH OTHER LAWS AND STATUTES Nothing in this permit will be construed as excusing the Permittee from compliance with any applicable federal, state, or local statutes, ordinances, or regulations. G8. DUTY TO REAPPLY The Permittee must apply for permit renewal at least 180 days prior to the specified expiration date of this permit. The Permittee must reapply using the electronic application form (NOI) available on Ecology’s website. Permittees unable to submit electronically (for example, those who do not have an internet connection) must contact Ecology to request a waiver and obtain instructions on how to obtain a paper NOI. Department of Ecology Water Quality Program - Construction Stormwater PO Box 47696 Olympia, Washington 98504-7696 Construction Stormwater General Permit Page 41 G9. TRANSFER OF GENERAL PERMIT COVERAGE Coverage under this general permit is automatically transferred to a new discharger, including operators of lots/parcels within a common plan of development or sale, if: A. A written agreement (Transfer of Coverage Form) between the current discharger (Permittee) and new discharger, signed by both parties and containing a specific date for transfer of permit responsibility, coverage, and liability (including any Administrative Orders associated with the Permit) is submitted to the Director; and B. The Director does not notify the current discharger and new discharger of the Director’s intent to revoke coverage under the general permit. If this notice is not given, the transfer is effective on the date specified in the written agreement. When a current discharger (Permittee) transfers a portion of a permitted site, the current discharger must also submit an updated application form (NOI) to the Director indicating the remaining permitted acreage after the transfer. G10. REMOVED SUBSTANCES The Permittee must not re-suspend or reintroduce collected screenings, grit, solids, sludges, filter backwash, or other pollutants removed in the course of treatment or control of stormwater to the final effluent stream for discharge to state waters. G11. DUTY TO PROVIDE INFORMATION The Permittee must submit to Ecology, within a reasonable time, all information that Ecology may request to determine whether cause exists for modifying, revoking and reissuing, or terminating this permit or to determine compliance with this permit. The Permittee must also submit to Ecology, upon request, copies of records required to be kept by this permit [40 CFR 122.41(h)]. G12. OTHER REQUIREMENTS OF 40 CFR All other requirements of 40 CFR 122.41 and 122.42 are incorporated in this permit by reference. G13. ADDITIONAL MONITORING Ecology may establish specific monitoring requirements in addition to those contained in this permit by administrative order or permit modification. G14. PENALTIES FOR VIOLATING PERMIT CONDITIONS Any person who is found guilty of willfully violating the terms and conditions of this permit shall be deemed guilty of a crime, and upon conviction thereof shall be punished by a fine of up to ten thousand dollars ($10,000) and costs of prosecution, or by imprisonment at the discretion of the court. Each day upon which a willful violation occurs may be deemed a separate and additional violation. Construction Stormwater General Permit Page 42 Any person who violates the terms and conditions of a waste discharge permit shall incur, in addition to any other penalty as provided by law, a civil penalty in the amount of up to ten thousand dollars ($10,000) for every such violation. Each and every such violation shall be a separate and distinct offense, and in case of a continuing violation, every day’s continuance shall be deemed to be a separate and distinct violation. G15. UPSET Definition – “Upset” means an exceptional incident in which there is unintentional and temporary noncompliance with technology-based permit effluent limitations because of factors beyond the reasonable control of the Permittee. An upset does not include noncompliance to the extent caused by operational error, improperly designed treatment facilities, inadequate treatment facilities, lack of preventive maintenance, or careless or improper operation. An upset constitutes an affirmative defense to an action brought for noncompliance with such technology-based permit effluent limitations if the requirements of the following paragraph are met. A Permittee who wishes to establish the affirmative defense of upset must demonstrate, through properly signed, contemporaneous operating logs or other relevant evidence that: 1) an upset occurred and that the Permittee can identify the cause(s) of the upset; 2) the permitted facility was being properly operated at the time of the upset; 3) the Permittee submitted notice of the upset as required in Special Condition S5.F, and; 4) the Permittee complied with any remedial measures required under this permit. In any enforcement proceeding, the Permittee seeking to establish the occurrence of an upset has the burden of proof. G16. PROPERTY RIGHTS This permit does not convey any property rights of any sort, or any exclusive privilege. G17. DUTY TO COMPLY The Permittee must comply with all conditions of this permit. Any permit noncompliance constitutes a violation of the Clean Water Act and is grounds for enforcement action; for permit termination, revocation and reissuance, or modification; or denial of a permit renewal application. G18. TOXIC POLLUTANTS The Permittee must comply with effluent standards or prohibitions established under Section 307(a) of the Clean Water Act for toxic pollutants within the time provided in the regulations that establish those standards or prohibitions, even if this permit has not yet been modified to incorporate the requirement. Construction Stormwater General Permit Page 43 G19. PENALTIES FOR TAMPERING The Clean Water Act provides that any person who falsifies, tampers with, or knowingly renders inaccurate any monitoring device or method required to be maintained under this permit shall, upon conviction, be punished by a fine of not more than $10,000 per violation, or by imprisonment for not more than two years per violation, or by both. If a conviction of a person is for a violation committed after a first conviction of such person under this condition, punishment shall be a fine of not more than $20,000 per day of violation, or imprisonment of not more than four (4) years, or both. G20. REPORTING PLANNED CHANGES The Permittee must, as soon as possible, give notice to Ecology of planned physical alterations, modifications or additions to the permitted construction activity. The Permittee should be aware that, depending on the nature and size of the changes to the original permit, a new public notice and other permit process requirements may be required. Changes in activities that require reporting to Ecology include those that will result in: A. The permitted facility being determined to be a new source pursuant to 40 CFR 122.29(b). B. A significant change in the nature or an increase in quantity of pollutants discharged, including but not limited to: for sites 5 acres or larger, a 20% or greater increase in acreage disturbed by construction activity. C. A change in or addition of surface water(s) receiving stormwater or non-stormwater from the construction activity. D. A change in the construction plans and/or activity that affects the Permittee’s monitoring requirements in Special Condition S4. Following such notice, permit coverage may be modified, or revoked and reissued pursuant to 40 CFR 122.62(a) to specify and limit any pollutants not previously limited. Until such modification is effective, any new or increased discharge in excess of permit limits or not specifically authorized by this permit constitutes a violation. G21. REPORTING OTHER INFORMATION Where the Permittee becomes aware that it failed to submit any relevant facts in a permit application, or submitted incorrect information in a permit application or in any report to Ecology, it must promptly submit such facts or information. G22. REPORTING ANTICIPATED NON-COMPLIANCE The Permittee must give advance notice to Ecology by submission of a new application or supplement thereto at least forty-five (45) days prior to commencement of such discharges, of any facility expansions, production increases, or other planned changes, such as process modifications, in the permitted facility or activity which may result in noncompliance with permit limits or conditions. Any maintenance of facilities, which might necessitate Construction Stormwater General Permit Page 44 unavoidable interruption of operation and degradation of effluent quality, must be scheduled during non-critical water quality periods and carried out in a manner approved by Ecology. G23. REQUESTS TO BE EXCLUDED FROM COVERAGE UNDER THE PERMIT Any discharger authorized by this permit may request to be excluded from coverage under the general permit by applying for an individual permit. The discharger must submit to the Director an application as described in WAC 173-220-040 or WAC 173-216-070, whichever is applicable, with reasons supporting the request. These reasons will fully document how an individual permit will apply to the applicant in a way that the general permit cannot. Ecology may make specific requests for information to support the request. The Director will either issue an individual permit or deny the request with a statement explaining the reason for the denial. When an individual permit is issued to a discharger otherwise subject to the construction stormwater general permit, the applicability of the construction stormwater general permit to that Permittee is automatically terminated on the effective date of the individual permit. G24. APPEALS A. The terms and conditions of this general permit, as they apply to the appropriate class of dischargers, are subject to appeal by any person within 30 days of issuance of this general permit, in accordance with Chapter 43.21B RCW, and Chapter 173-226 WAC. B. The terms and conditions of this general permit, as they apply to an individual discharger, are appealable in accordance with Chapter 43.21B RCW within 30 days of the effective date of coverage of that discharger. Consideration of an appeal of general permit coverage of an individual discharger is limited to the general permit’s applicability or nonapplicability to that individual discharger. C. The appeal of general permit coverage of an individual discharger does not affect any other dischargers covered under this general permit. If the terms and conditions of this general permit are found to be inapplicable to any individual discharger(s), the matter shall be remanded to Ecology for consideration of issuance of an individual permit or permits. G25. SEVERABILITY The provisions of this permit are severable, and if any provision of this permit, or application of any provision of this permit to any circumstance, is held invalid, the application of such provision to other circumstances, and the remainder of this permit shall not be affected thereby. G26. BYPASS PROHIBITED A. Bypass Procedures Bypass, which is the intentional diversion of waste streams from any portion of a treatment facility, is prohibited for stormwater events below the design criteria for Construction Stormwater General Permit Page 45 stormwater management. Ecology may take enforcement action against a Permittee for bypass unless one of the following circumstances (1, 2, 3 or 4) is applicable. 1. Bypass of stormwater is consistent with the design criteria and part of an approved management practice in the applicable stormwater management manual. 2. Bypass for essential maintenance without the potential to cause violation of permit limits or conditions. Bypass is authorized if it is for essential maintenance and does not have the potential to cause violations of limitations or other conditions of this permit, or adversely impact public health. 3. Bypass of stormwater is unavoidable, unanticipated, and results in noncompliance of this permit. This bypass is permitted only if: a. Bypass is unavoidable to prevent loss of life, personal injury, or severe property damage. “Severe property damage” means substantial physical damage to property, damage to the treatment facilities which would cause them to become inoperable, or substantial and permanent loss of natural resources which can reasonably be expected to occur in the absence of a bypass. b. There are no feasible alternatives to the bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, maintenance during normal periods of equipment downtime (but not if adequate backup equipment should have been installed in the exercise of reasonable engineering judgment to prevent a bypass which occurred during normal periods of equipment downtime or preventative maintenance), or transport of untreated wastes to another treatment facility. c. Ecology is properly notified of the bypass as required in Special Condition S5.F of this permit. 4. A planned action that would cause bypass of stormwater and has the potential to result in noncompliance of this permit during a storm event. The Permittee must notify Ecology at least thirty (30) days before the planned date of bypass. The notice must contain: a. A description of the bypass and its cause. b. An analysis of all known alternatives which would eliminate, reduce, or mitigate the need for bypassing. c. A cost-effectiveness analysis of alternatives including comparative resource damage assessment. d. The minimum and maximum duration of bypass under each alternative. e. A recommendation as to the preferred alternative for conducting the bypass. Construction Stormwater General Permit Page 46 f. The projected date of bypass initiation. g. A statement of compliance with SEPA. h. A request for modification of water quality standards as provided for in WAC 173-201A-110, if an exceedance of any water quality standard is anticipated. i. Steps taken or planned to reduce, eliminate, and prevent reoccurrence of the bypass. 5. For probable construction bypasses, the need to bypass is to be identified as early in the planning process as possible. The analysis required above must be considered during preparation of the Stormwater Pollution Prevention Plan (SWPPP) and must be included to the extent practical. In cases where the probable need to bypass is determined early, continued analysis is necessary up to and including the construction period in an effort to minimize or eliminate the bypass. Ecology will consider the following before issuing an administrative order for this type bypass: a. If the bypass is necessary to perform construction or maintenance-related activities essential to meet the requirements of this permit. b. If there are feasible alternatives to bypass, such as the use of auxiliary treatment facilities, retention of untreated wastes, stopping production, maintenance during normal periods of equipment down time, or transport of untreated wastes to another treatment facility. c. If the bypass is planned and scheduled to minimize adverse effects on the public and the environment. After consideration of the above and the adverse effects of the proposed bypass and any other relevant factors, Ecology will approve, conditionally approve, or deny the request. The public must be notified and given an opportunity to comment on bypass incidents of significant duration, to the extent feasible. Approval of a request to bypass will be by administrative order issued by Ecology under RCW 90.48.120. B. Duty to Mitigate The Permittee is required to take all reasonable steps to minimize or prevent any discharge or sludge use or disposal in violation of this permit that has a reasonable likelihood of adversely affecting human health or the environment. Construction Stormwater General Permit Page 47 APPENDIX A – DEFINITIONS AKART is an acronym for “all known, available, and reasonable methods of prevention, control, and treatment.” AKART represents the most current methodology that can be reasonably required for preventing, controlling, or abating the pollutants and controlling pollution associated with a discharge. Applicable TMDL means a TMDL for turbidity, fine sediment, high pH, or phosphorus, which was completed and approved by EPA before January 1, 2016, or before the date the operator’s complete permit application is received by Ecology, whichever is later. Applicant means an operator seeking coverage under this permit. Benchmark means a pollutant concentration used as a permit threshold, below which a pollutant is considered unlikely to cause a water quality violation, and above which it may. When pollutant concentrations exceed benchmarks, corrective action requirements take effect. Benchmark values are not water quality standards and are not numeric effluent limitations; they are indicator values. Best Management Practices (BMPs) means schedules of activities, prohibitions of practices, maintenance procedures, and other physical, structural and/or managerial practices to prevent or reduce the pollution of waters of the State. BMPs include treatment systems, operating procedures, and practices to control: stormwater associated with construction activity, spillage or leaks, sludge or waste disposal, or drainage from raw material storage. Buffer means an area designated by a local jurisdiction that is contiguous to and intended to protect a sensitive area. Bypass means the intentional diversion of waste streams from any portion of a treatment facility. Calendar Day A period of 24 consecutive hours starting at 12:00 midnight and ending the following 12:00 midnight. Calendar Week (same as Week) means a period of seven consecutive days starting at 12:01 a.m. (0:01 hours) on Sunday. Certified Erosion and Sediment Control Lead (CESCL) means a person who has current certification through an approved erosion and sediment control training program that meets the minimum training standards established by Ecology (see BMP C160 in the SWMM). Chemical Treatment means the addition of chemicals to stormwater and/or authorized non- stormwater prior to filtration and discharge to surface waters. Clean Water Act (CWA) means the Federal Water Pollution Control Act enacted by Public Law 92-500, as amended by Public Laws 95-217, 95-576, 96-483, and 97-117; USC 1251 et seq. Combined Sewer means a sewer which has been designed to serve as a sanitary sewer and a storm sewer, and into which inflow is allowed by local ordinance. Construction Stormwater General Permit Page 48 Common Plan of Development or Sale means a site where multiple separate and distinct construction activities may be taking place at different times on different schedules and/or by different contractors, but still under a single plan. Examples include: 1) phased projects and projects with multiple filings or lots, even if the separate phases or filings/lots will be constructed under separate contract or by separate owners (e.g., a development where lots are sold to separate builders); 2) a development plan that may be phased over multiple years, but is still under a consistent plan for long-term development; 3) projects in a contiguous area that may be unrelated but still under the same contract, such as construction of a building extension and a new parking lot at the same facility; and 4) linear projects such as roads, pipelines, or utilities. If the project is part of a common plan of development or sale, the disturbed area of the entire plan must be used in determining permit requirements. Composite Sample means a mixture of grab samples collected at the same sampling point at different times, formed either by continuous sampling or by mixing discrete samples. May be "time-composite" (collected at constant time intervals) or "flow-proportional" (collected either as a constant sample volume at time intervals proportional to stream flow, or collected by increasing the volume of each aliquot as the flow increases while maintaining a constant time interval between the aliquots. Concrete Wastewater means any water used in the production, pouring and/or clean-up of concrete or concrete products, and any water used to cut, grind, wash, or otherwise modify concrete or concrete products. Examples include water used for or resulting from concrete truck/mixer/pumper/tool/chute rinsing or washing, concrete saw cutting and surfacing (sawing, coring, grinding, roughening, hydro-demolition, bridge and road surfacing). When stormwater comingles with concrete wastewater, the resulting water is considered concrete wastewater and must be managed to prevent discharge to waters of the State, including ground water. Construction Activity means land disturbing operations including clearing, grading or excavation which disturbs the surface of the land. Such activities may include road construction, construction of residential houses, office buildings, or industrial buildings, site preparation, soil compaction, movement and stockpiling of topsoils, and demolition activity. Contaminant means any hazardous substance that does not occur naturally or occurs at greater than natural background levels. See definition of “hazardous substance” and WAC 173-340-200. Contaminated Groundwater means groundwater which contains contaminants, pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Contaminated Soil means soil which contains contaminants, pollutants, or hazardous substances that do not occur naturally or occur at levels greater than natural background. Demonstrably Equivalent means that the technical basis for the selection of all stormwater BMPs is documented within a SWPPP, including: 1. The method and reasons for choosing the stormwater BMPs selected. Construction Stormwater General Permit Page 49 2. The pollutant removal performance expected from the BMPs selected. 3. The technical basis supporting the performance claims for the BMPs selected, including any available data concerning field performance of the BMPs selected. 4. An assessment of how the selected BMPs will comply with state water quality standards. 5. An assessment of how the selected BMPs will satisfy both applicable federal technology- based treatment requirements and state requirements to use all known, available, and reasonable methods of prevention, control, and treatment (AKART). Department means the Washington State Department of Ecology. Detention means the temporary storage of stormwater to improve quality and/or to reduce the mass flow rate of discharge. Dewatering means the act of pumping ground water or stormwater away from an active construction site. Director means the Director of the Washington State Department of Ecology or his/her authorized representative. Discharger means an owner or operator of any facility or activity subject to regulation under Chapter 90.48 RCW or the Federal Clean Water Act. Domestic Wastewater means water carrying human wastes, including kitchen, bath, and laundry wastes from residences, buildings, industrial establishments, or other places, together with such ground water infiltration or surface waters as may be present. Ecology means the Washington State Department of Ecology. Engineered Soils means the use of soil amendments including, but not limited, to Portland cement treated base (CTB), cement kiln dust (CKD), or fly ash to achieve certain desirable soil characteristics. Equivalent BMPs means operational, source control, treatment, or innovative BMPs which result in equal or better quality of stormwater discharge to surface water or to ground water than BMPs selected from the SWMM. Erosion means the wearing away of the land surface by running water, wind, ice, or other geological agents, including such processes as gravitational creep. Erosion and Sediment Control BMPs means BMPs intended to prevent erosion and sedimentation, such as preserving natural vegetation, seeding, mulching and matting, plastic covering, filter fences, sediment traps, and ponds. Erosion and sediment control BMPs are synonymous with stabilization and structural BMPs. Federal Operator is an entity that meets the definition of “Operator” in this permit and is either any department, agency or instrumentality of the executive, legislative, and judicial branches of Construction Stormwater General Permit Page 50 the Federal government of the United States, or another entity, such as a private contractor, performing construction activity for any such department, agency, or instrumentality. Final Stabilization (same as fully stabilized or full stabilization) means the establishment of a permanent vegetative cover, or equivalent permanent stabilization measures (examples of permanent non-vegetative stabilization methods include, but are not limited to riprap, gabions or geotextiles) which prevents erosion. Ground Water means water in a saturated zone or stratum beneath the land surface or a surface waterbody. Hazardous Substance means any dangerous or extremely hazardous waste as defined in RCW 70.105.010 (5) and (6), or any dangerous or extremely dangerous waste as designated by rule under chapter 70.105 RCW; any hazardous substance as defined in RCW 70.105.010(10) or any hazardous substance as defined by rule under chapter 70.105 RCW; any substance that, on the effective date of this section, is a hazardous substance under section 101(14) of the federal cleanup law, 42 U.S.C., Sec. 9601(14); petroleum or petroleum products; and any substance or category of substances, including solid waste decomposition products, determined by the director by rule to present a threat to human health or the environment if released into the environment . The term hazardous substance does not include any of the following when contained in an underground storage tank from which there is not a release: crude oil or any fraction thereof or petroleum, if the tank is in compliance with all applicable federal, state, and local law. Injection Well means a well that is used for the subsurface emplacement of fluids. (See Well.) Jurisdiction means a political unit such as a city, town or county; incorporated for local self- government. National Pollutant Discharge Elimination System (NPDES) means the national program for issuing, modifying, revoking and reissuing, terminating, monitoring, and enforcing permits, and imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the Federal Clean Water Act, for the discharge of pollutants to surface waters of the State from point sources. These permits are referred to as NPDES permits and, in Washington State, are administered by the Washington State Department of Ecology. Notice of Intent (NOI) means the application for, or a request for coverage under this general permit pursuant to WAC 173-226-200. Notice of Termination (NOT) means a request for termination of coverage under this general permit as specified by Special Condition S10 of this permit. Operator means any party associated with a construction project that meets either of the following two criteria:  The party has operational control over construction plans and specifications, including the ability to make modifications to those plans and specifications; or Construction Stormwater General Permit Page 51  The party has day-to-day operational control of those activities at a project that are necessary to ensure compliance with a SWPPP for the site or other permit conditions (e.g., they are authorized to direct workers at a site to carry out activities required by the SWPPP or comply with other permit conditions). Permittee means individual or entity that receives notice of coverage under this general permit. pH means a liquid’s measure of acidity or alkalinity. A pH of 7 is defined as neutral. Large variations above or below this value are considered harmful to most aquatic life. pH Monitoring Period means the time period in which the pH of stormwater runoff from a site must be tested a minimum of once every seven days to determine if stormwater pH is between 6.5 and 8.5. Point Source means any discernible, confined, and discrete conveyance, including but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, and container from which pollutants are or may be discharged to surface waters of the State. This term does not include return flows from irrigated agriculture. (See Fact Sheet for further explanation.) Pollutant means dredged spoil, solid waste, incinerator residue, filter backwash, sewage, garbage, domestic sewage sludge (biosolids), munitions, chemical wastes, biological materials, radioactive materials, heat, wrecked or discarded equipment, rock, sand, cellar dirt, and industrial, municipal, and agricultural waste. This term does not include sewage from vessels within the meaning of section 312 of the CWA, nor does it include dredged or fill material discharged in accordance with a permit issued under section 404 of the CWA. Pollution means contamination or other alteration of the physical, chemical, or biological properties of waters of the State; including change in temperature, taste, color, turbidity, or odor of the waters; or such discharge of any liquid, gaseous, solid, radioactive or other substance into any waters of the State as will or is likely to create a nuisance or render such waters harmful, detrimental or injurious to the public health, safety or welfare; or to domestic, commercial, industrial, agricultural, recreational, or other legitimate beneficial uses; or to livestock, wild animals, birds, fish or other aquatic life. Process Wastewater means any water which, during manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product, byproduct, or waste product. If stormwater commingles with process wastewater, the commingled water is considered process wastewater. Receiving Water means the waterbody at the point of discharge. If the discharge is to a storm sewer system, either surface or subsurface, the receiving water is the waterbody to which the storm system discharges. Systems designed primarily for other purposes such as for ground water drainage, redirecting stream natural flows, or for conveyance of irrigation water/return flows that coincidentally convey stormwater are considered the receiving water. Construction Stormwater General Permit Page 52 Representative means a stormwater or wastewater sample which represents the flow and characteristics of the discharge. Representative samples may be a grab sample, a time- proportionate composite sample, or a flow proportionate sample. Ecology’s Construction Stormwater Monitoring Manual provides guidance on representative sampling. Responsible Corporate Officer for the purpose of signatory authority means: (i) a president, secretary, treasurer, or vice-president of the corporation in charge of a principal business function, or any other person who performs similar policy- or decision-making functions for the corporation, or (ii) the manager of one or more manufacturing, production, or operating facilities, provided, the manager is authorized to make management decisions which govern the operation of the regulated facility including having the explicit or implicit duty of making major capital investment recommendations, and initiating and directing other comprehensive measures to assure long term environmental compliance with environmental laws and regulations; the manager can ensure that the necessary systems are established or actions taken to gather complete and accurate information for permit application requirements; and where authority to sign documents has been assigned or delegated to the manager in accordance with corporate procedures (40 CFR 122.22). Sanitary Sewer means a sewer which is designed to convey domestic wastewater. Sediment means the fragmented material that originates from the weathering and erosion of rocks or unconsolidated deposits, and is transported by, suspended in, or deposited by water. Sedimentation means the depositing or formation of sediment. Sensitive Area means a waterbody, wetland, stream, aquifer recharge area, or channel migration zone. SEPA (State Environmental Policy Act) means the Washington State Law, RCW 43.21C.020, intended to prevent or eliminate damage to the environment. Significant Amount means an amount of a pollutant in a discharge that is amenable to available and reasonable methods of prevention or treatment; or an amount of a pollutant that has a reasonable potential to cause a violation of surface or ground water quality or sediment management standards. Significant Concrete Work means greater than 1000 cubic yards poured concrete used over the life of a project. Significant Contributor of Pollutants means a facility determined by Ecology to be a contributor of a significant amount(s) of a pollutant(s) to waters of the State of Washington. Site means the land or water area where any "facility or activity" is physically located or conducted. Source Control BMPs means physical, structural or mechanical devices or facilities that are intended to prevent pollutants from entering stormwater. A few examples of source control Construction Stormwater General Permit Page 53 BMPs are erosion control practices, maintenance of stormwater facilities, constructing roofs over storage and working areas, and directing wash water and similar discharges to the sanitary sewer or a dead end sump. Stabilization means the application of appropriate BMPs to prevent the erosion of soils, such as, temporary and permanent seeding, vegetative covers, mulching and matting, plastic covering and sodding. See also the definition of Erosion and Sediment Control BMPs. Storm Drain means any drain which drains directly into a storm sewer system, usually found along roadways or in parking lots. Storm Sewer System means a means a conveyance, or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, manmade channels, or storm drains designed or used for collecting or conveying stormwater. This does not include systems which are part of a combined sewer or Publicly Owned Treatment Works (POTW) as defined at 40 CFR 122.2. Stormwater means that portion of precipitation that does not naturally percolate into the ground or evaporate, but flows via overland flow, interflow, pipes, and other features of a stormwater drainage system into a defined surface waterbody, or a constructed infiltration facility. Stormwater Management Manual (SWMM) or Manual means the technical Manual published by Ecology for use by local governments that contain descriptions of and design criteria for BMPs to prevent, control, or treat pollutants in stormwater. Stormwater Pollution Prevention Plan (SWPPP) means a documented plan to implement measures to identify, prevent, and control the contamination of point source discharges of stormwater. Surface Waters of the State includes lakes, rivers, ponds, streams, inland waters, salt waters, and all other surface waters and water courses within the jurisdiction of the State of Washington. Temporary Stabilization means the exposed ground surface has been covered with appropriate materials to provide temporary stabilization of the surface from water or wind erosion. Materials include, but are not limited to, mulch, riprap, erosion control mats or blankets and temporary cover crops. Seeding alone is not considered stabilization. Temporary stabilization is not a substitute for the more permanent “final stabilization.” Total Maximum Daily Load (TMDL) means a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet state water quality standards. Percentages of the total maximum daily load are allocated to the various pollutant sources. A TMDL is the sum of the allowable loads of a single pollutant from all contributing point and nonpoint sources. The TMDL calculations must include a "margin of safety" to ensure that the waterbody can be protected in case there are unforeseen events or unknown sources of the pollutant. The calculation must also account for seasonable variation in water quality. Construction Stormwater General Permit Page 54 Transfer of Coverage (TOC) means a request for transfer of coverage under this general permit as specified by General Condition G9 of this permit. Treatment BMPs means BMPs that are intended to remove pollutants from stormwater. A few examples of treatment BMPs are detention ponds, oil/water separators, biofiltration, and constructed wetlands. Transparency means a measurement of water clarity in centimeters (cm), using a 60 cm transparency tube. The transparency tube is used to estimate the relative clarity or transparency of water by noting the depth at which a black and white Secchi disc becomes visible when water is released from a value in the bottom of the tube. A transparency tube is sometimes referred to as a “turbidity tube.” Turbidity means the clarity of water expressed as nephelometric turbidity units (NTUs) and measured with a calibrated turbidimeter. Uncontaminated means free from any contaminant. See definition of “contaminant” and WAC 173-340-200. Waste Load Allocation (WLA) means the portion of a receiving water’s loading capacity that is allocated to one of its existing or future point sources of pollution. WLAs constitute a type of water quality based effluent limitation (40 CFR 130.2[h]). Water-only Based Shaft Drilling is a shaft drilling process that uses water only and no additives are involved in the drilling of shafts for construction of building, road, or bridge foundations. Water quality means the chemical, physical, and biological characteristics of water, usually with respect to its suitability for a particular purpose. Waters of the State includes those waters as defined as "waters of the United States" in 40 CFR Subpart 122.2 within the geographic boundaries of Washington State and "waters of the State" as defined in Chapter 90.48 RCW, which include lakes, rivers, ponds, streams, inland waters, underground waters, salt waters, and all other surface waters and water courses within the jurisdiction of the state of Washington. Well means a bored, drilled or driven shaft, or dug hole whose depth is greater than the largest surface dimension. (See Injection well.) Wheel Wash Wastewater means any water used in, or resulting from the operation of, a tire bath or wheel wash (BMP C106: Wheel Wash), or other structure or practice that uses water to physically remove mud and debris from vehicles leaving a construction site and prevent track- out onto roads. When stormwater comingles with wheel wash wastewater, the resulting water is considered wheel wash wastewater and must be managed according to Special Condition S9.D.9. Construction Stormwater General Permit Page 55 APPENDIX B – ACRONYMS AKART All Known, Available, and Reasonable Methods of Prevention, Control, and Treatment BMP Best Management Practice CESCL Certified Erosion and Sediment Control Lead CFR Code of Federal Regulations CKD Cement Kiln Dust cm Centimeters CTB Cement-Treated Base CWA Clean Water Act DMR Discharge Monitoring Report EPA Environmental Protection Agency ERTS Environmental Report Tracking System ESC Erosion and Sediment Control FR Federal Register LID Low Impact Development NOI Notice of Intent NOT Notice of Termination NPDES National Pollutant Discharge Elimination System NTU Nephelometric Turbidity Unit RCW Revised Code of Washington SEPA State Environmental Policy Act SWMM Stormwater Management Manual SWPPP Stormwater Pollution Prevention Plan TMDL Total Maximum Daily Load UIC Underground Injection Control USC United States Code USEPA United States Environmental Protection Agency WAC Washington Administrative Code WQ Water Quality WWHM Western Washington Hydrology Model Appendix F - 303(d) List Waterbodies / TMDL Waterbodies Information Appendix G - Contaminated Site Information No contaminated soils or groundwater expected - update as necessary. See 2015 RBM Assessment Report for various hazardous materials present in buildings to be demolished. Appendix H - Engineering Calculations Update as necessary to support phase specific erosion control measures. Madrona School – Edmonds School District Appendix H Appendix H Operation and Maintenance Manual R Call 811 MARK DATE DESCRIPTION 1500129 JCG/TJE 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com UIC WELL MAINTENANCE MANUAL UIC WELL MANIFOLD PIPE 1. MANIFOLD PIPES AND CONNECTED STRUCTURES SHOULD BE INSPECTED EVERY MONTH DURING THE FIRST YEAR OF OPERATION AND EVERY 6 MONTHS THEREAFTER FOR SEDIMENT BUILDUP. 2. IF ANY SEDIMENT IS FOUND DURING INSPECTION, IT SHOULD IMMEDIATELY BE REMOVED. 3. DURING MANIFOLD MAINTENANCE JETTING OPERATIONS, THE OUTLETS TO THE UIC WELLS SHALL BE PLUGGED TO PREVENT SEDIMENT FROM ENTERING AND FOULING THE UIC WELLS. 1 2 3 R Call 811 MARK DATE DESCRIPTION 1500129 JCG/TJE 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com LEGEND UIC WELL MANIFOLD PIPE 1. MANIFOLD PIPES AND CONNECTED STRUCTURES SHOULD BE INSPECTED EVERY MONTH DURING THE FIRST YEAR OF OPERATION AND EVERY 6 MONTHS THEREAFTER FOR SEDIMENT BUILDUP. 2. IF ANY SEDIMENT IS FOUND DURING INSPECTION, IT SHOULD IMMEDIATELY BE REMOVED. 3. DURING MANIFOLD MAINTENANCE JETTING OPERATIONS, THE OUTLETS TO THE UIC WELLS SHALL BE PLUGGED TO PREVENT SEDIMENT FROM ENTERING AND FOULING THE UIC WELLS. 1 R Call 811 MARK DATE DESCRIPTION 1500129 JCG/TJE 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com 1. MANIFOLD PIPES AND CONNECTED STRUCTURES SHOULD BE INSPECTED EVERY MONTH DURING THE FIRST YEAR OF OPERATION AND EVERY 6 MONTHS THEREAFTER FOR SEDIMENT BUILDUP. 2. IF ANY SEDIMENT IS FOUND DURING INSPECTION, IT SHOULD IMMEDIATELY BE REMOVED. 3. DURING MANIFOLD MAINTENANCE JETTING OPERATIONS, THE OUTLETS TO THE UIC WELLS SHALL BE PLUGGED TO PREVENT SEDIMENT FROM ENTERING AND FOULING THE UIC WELLS. LEGEND UIC WELL MANIFOLD PIPE 2 R Call 811 MARK DATE DESCRIPTION 1500129 JCG/TJE 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com 1. MANIFOLD PIPES AND CONNECTED STRUCTURES SHOULD BE INSPECTED EVERY MONTH DURING THE FIRST YEAR OF OPERATION AND EVERY 6 MONTHS THEREAFTER FOR SEDIMENT BUILDUP. 2. IF ANY SEDIMENT IS FOUND DURING INSPECTION, IT SHOULD IMMEDIATELY BE REMOVED. 3. DURING MANIFOLD MAINTENANCE JETTING OPERATIONS, THE OUTLETS TO THE UIC WELLS SHALL BE PLUGGED TO PREVENT SEDIMENT FROM ENTERING AND FOULING THE UIC WELLS. LEGEND UIC WELL MANIFOLD PIPE 3 R Call 811 MARK DATE DESCRIPTION 1500129 JCG/TJE 1601 5th Avenue, Suite 1600 Seattle, WA 98101 206.622.5822 www.kpff.com MAINTAINABLE SAND LAYERS NOTES: 1. UIC WELLS SHOULD BE INSPECTED EVERY MONTH DURING THE FIRST YEAR OF OPERATION AND EVERY 6 MONTHS THEREAFTER FOR SEDIMENT BUILDUP. 2. IF SEDIMENT HAS ACCUMULATED AT THE SURFACE OF THE UIC FILTER SAND IT SHOULD IMMEDIATELY REMOVED AND THE SAND LAYERS SHOULD BE REPLACED WITH FRESH SAND MEETING THE ORIGINAL SPECIFICATIONS LAYER THICKNESSES. 3. WELLS SHOULD BE TESTED YEARLY TO CONFIRM INFILTRATIVE CAPACITY. 4