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APPROVED STM Hill Residence Drainage Report (1)C � ENGINEERING 250 4th Ave S Ste 200 Edmonds, WA 98020 Phone: (425) 778-8500 Fax: (425) 778-5536 civil & structural engineering & planning DRAINAGE REPORT Hill Residence 8112 Talbot Rd. Edmonds, WA 98026 0610212021 CG Project No.: 20439 Table of Contents Section I — Project Overview Section II — Off -Site Analysis Section III — Permanent Stormwater Control Plan Section IV— Construction Stormwater Pollution Prevention Plan Section V — Special Reports and/or Studies Section VI — Other Permits Section VII — Bond Quantities, Declaration of Covenant, & Operation and Maintenance Manual 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section I, Page 1 Section I — Project Overview Section I Summa Overview Existing Condition Developed Condition Minimum Requirements Overview This stormwater site plan has been written for site and utility improvements on a 0.77 ac lot located at 8112 Talbot Rd in Edmonds, WA (TPN: 0059-440000-8701). Site improvements being made to the areas surrounding the existing house include a new driveway, an outdoor concrete sport court, a gravel backyard, and concrete walkways. A total of 8,094 new/replaced impervious area is proposed for this project (including ROW improvements). Utility improvements include tying all new and replaced impervious surfaces on -site to a new drainage system and addressing existing drainage issues on -site and in the ROW. There is an existing driveway, concrete path, and concrete slab that will be demolished. Since the project will add 5,000 sf or more of new plus replaced hard surface area, the project is classified as Category 2 per City of Edmonds. Category 2 projects are required to comply with Minimum Requirements 1 through 9 from the Edmonds Community Development Code Chapter 18.30 (ECDC 18.30) and the Edmonds Stormwater Addendum. Existing Condition The site is currently developed with a house, covered porch, shed, asphalt driveway, concrete walkway, concrete driveway extension, and landscaping. The site is an irregularly shaped parcel of 32,820 sf (0.77 ac) lot with the long side spanning north to south. The north side of the site is where the existing development is contained, and the south side of the site is undeveloped. According to the Geotechnical Report, the site soils consist of sandy organic topsoils with underlying native silty sand, closely resembling a recessional glacial outwash soil. Infiltration on -site was found to be infeasible due to the visible delay of stormwater infiltration in the existing condition. The site is bordered by single-family residences to the south, east, and west and the intersection of Talbot Rd and Cyrus PI to the north. The southern half of the project parcel is occupied by two steep downslopes and the Perrinville Creek. The areas surrounding the creek are considered landslide and erosion hazard areas by the City of Edmonds since they consist of slopes greater than 40%. A landslide/erosion hazard map can be found in Section II in Figure II-2. The existing house is at a relatively low grade, and stormwater that collects on the driveway currently flows west towards the house. There is one 12" yard drain at a low point in the driveway which conveys stormwater to a small rock pond east of the house. Otherwise, stormwater runoff from the driveway and yard surrounding the house tend to flow back towards the house and cause flooding. Roof downspouts 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section I, Page 2 daylight to the existing landscaping in front of the house. There is an existing catch basin in the ROW directly in front of the driveway to collect runoff from Cyrus PI. However, this catch basin does not properly catch all of the upstream runoff, and there are problems of ponding and flooding at the north end of the homeowner's driveway. This is due to the slope of the road pavement and no good path for the road drainage to be picked up by the existing catch basin inlets. The site is in the Perrinville Creek Watershed. The existing impervious areas are as follows: Impervious Areas Roof: 4,004 sf (0.092 ac) Concrete Walkways: 1,496 sf (0.034 ac) Asphalt Driveway: 5,136 sf (0.118 ac) Total: 10,636 sf (0.244 ac) Developed Condition The project consists of the construction of several site improvements and utility improvements around an existing house. The existing asphalt driveway will be replaced with a new concrete paver driveway and a portion of the existing landscaped backyard will be replaced with a gravel backyard area. A concrete sport court will be built where the existing driveway extension is, and new concrete path on the north side of the house will replace the existing one. The existing roof downspouts will be tightlined to stormwater management BMPs, and footing drains will be added around parts of the house. The total of new plus replaced impervious areas is 8,920 sf (0.205 ac). Land disturbance will affect the entire northern half area of the site. The site will utilize an infiltration trench to address Minimum Requirement #5: On -Site Stormwater Management. A 27' x 10' x 3' infiltration trench with an overflow pipe connecting to the public storm system will be placed in the front yard. It will collect runoff from all new/replaced impervious areas on site as well as runoff from the roof via a proposed tightline system. More on the drainage system can be found on the civil plans sheet C3.1. See Section VII for the vegetation management plan. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section I, Page 3 The proposed impervious areas are as follows: Impervious Areas Roof (existing): 3,896 sf (0.089 ac) Concrete Pavers: 4,119 sf (0.094 ac) Concrete Sidewalk/Sport Court: 1,356 sf (0.031 ac) Gravel Backyard/Courtyard: 2,619 sf (0.060 ad Total: 11,990 sf (0.275 ac) The new and replaced pollution -generating impervious areas are as follows: Pollution -generating impervious areas Driveway: 4,119 sf (0.094 ac) Total: 4,119 sf (0.094 ac) 2 26 Total project area: 0.77 ac Total hard surfaces (New+Replaced): 0.19 " ac. PGHS/PGIS: 0.09 ac Total disturbed area: 0.45 ac f� / Average slope: 5% �C NRCS soil group: B PROJECT SITE 4� X A 2-24 2- 00 96 2-223 `1 d lit Cc Figure 1-1. Vicinity map showing project site and flow paths (City of Edmonds GIS Map). CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section I, Page 4 Figure 1-2. Map showing existing stormwater utilities near site (City of Edmonds GIS Map). See Grading and Drainage Plan for more details. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section I, Page 5 Mft Figure 1-3. Aerial photograph of site. CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section I, Page 6 Minimum Requirements Stormwater requirements were determined per the December 2016 Addendum to Edmonds Community Development Code Chapter 18.30 (Edmonds Stormwater Addendum), the Edmonds Community Development Code (EDCC) Chapter 18.30, and the 2014 Stormwater Management Manual for Western Washington by the Department of Ecology (SWMMWW). This report is based on the steps recommended in Chapter 7 of the Edmonds Stormwater Addendum. The project is classified as a Category 2 Project Using Figure 3.1 in the Edmonds Stormwater Addendum and will comply with Minimum Requirements #1-9. Minimum Requirement #1: Preparation of Stormwater Site Plans: The stormwater site plan consists of this report and the civil drawings, and is prepared in accordance with Chapter 3 of Volume 1 of the SWMMWW and the requirements in the Edmonds Stormwater Addendum. Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan (SWPPP): The SWPPP shall include a narrative and drawings. A full DOE SWPPP that addresses the 13 elements of Construction Stormwater Pollution Prevention has been prepared. See Section IV and the civil drawings. Minimum Requirement #3: Source Control of Pollution: All known, available and reasonable source control BMPs must be required for all projects approved by the city. All single-family residential projects shall, at a minimum, incorporate required BMPs from SWMMWW Volume IV, S411 — BMPs for Landscaping and Lawn/Vegetation Management. The Operation & Maintenance Manual found in Section VII addresses Lawn/Vegetation management. Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls: Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down gradient properties. All projects shall submit an off -site qualitative analysis. A qualitative analysis of the upstream and downstream system entering the site is presented in Section II. Minimum Requirement #5: On -Site Stormwater Management: The proposed project is a Category 2 project per ECDC 18.30 that discharges to the City's MS4. It shall either use On -Site Stormwater Management BMPs from List No. 2 (per ECDC 18.30.060.D.5.e) for all new plus replaced hard surfaces and land disturbed, or demonstrate compliance with the LID Performance Standard (per ECDC 18.30.060.D.5.c ). This project will demonstrate compliance with the LID Performance Standard. See Section III for further calculations. Post -construction soil quality and depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the SWMMWW will be used for all disturbed pervious areas. Minimum Requirement #6: Runoff Treatment: This requirement applies to the new plus replaced hard surfaces and the converted vegetation areas. The following require construction of stormwater treatment facilities: i.) Projects in which the total of pollution -generating hard surface (PGHS) is 5,000 square feet or more in a threshold discharge area of the project, or ii.) projects in which the total of pollution -generating pervious surfaces (PGPS) — not including permeable pavements is 0.75 acres or more in a threshold 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section I, Page 7 discharge area, and from which there will be a surface discharge in a natural or man-made conveyance system from the site. This project's total of PGHS is less than 5,000 square feet and runoff treatment is not required. Minimum Requirement #7: Flow Control: Projects must provide flow control to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions. The requirement below applies to projects that discharge stormwater directly, or indirectly through a conveyance system, into a fresh waterbody. Flow control is not required for projects that discharge directly to, or indirectly through the City's MS4 to Puget Sound. The following circumstances require achievement of the standard flow control requirement for western Washington: i.) Projects in which the total of effective impervious surfaces is 10,000 square feet or more in a threshold discharge area, or ii.) projects that convert 0.75 acres or more of vegetation to lawn or landscape, or iii.) projects that through a combination of hard surfaces and converted vegetation areas cause a 0.15 cubic feet per second (cfs) increase or greater in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other approved model and 15-minute time steps. The total target effective new/replaced hard surfaces in the threshold discharge area is 8,094 sf, there is no vegetation to be converted to lawn/landscape, and the difference between predeveloped and mitigated flows is less than 0.01 cfs. Therefore, the project does not require flow control. The WWHM report for the flow increase check can be found in Section III. Minimum Requirement #8: Wetlands Protection: Projects shall comply with Guide Sheets #1 through #3 in Appendix I-D of the SWMMWW. The hydrologic analysis shall use the existing land cover condition to determine the existing hydrologic conditions unless directed otherwise by a regulatory agency with jurisdiction. The requirements apply only to projects whose stormwater discharges into a wetland, either directly or indirectly through a conveyance system. This project site's stormwater does not discharge into a wetland and does not require wetland protection. Minimum Requirement #9: Operation and Maintenance: An operation and maintenance manual that is consistent with the provisions in Volume I and Volume V of the SWMMWW is required for proposed Stormwater Treatment and Flow Control BMPs/facilities. The party (or parties) responsible for maintenance and operation shall be identified in the operation and maintenance manual. For private facilities approved by the City, a copy of the operation and maintenance manual shall be retained on -site or within reasonable access to the site, and shall be transferred with the property to the new owner. For public facilities, a copy of the operation and maintenance manual shall be retained in the appropriate department. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section I, Page 8 [kx:s the project result in 2,000 square feet, or greater, urnew plus replaced hard surface area? OR Ikx s the land disturbing activity total 7,000 square feet or greater? es me Minimum RequircmcnLs No. I through 5 apply Minimum Requirement No. 2 applies Next Uunesfion Dees the project add 5,000 square feet or more of new plus replaced hard surfaces? OR Convert 0.75 acres or more of vegetation to lawn or landscaped areas? OR Convert 2.5 acres or mart of native vegetation to pasture? Yes 140 r-- Is this a road related project` All Minimum RcquLrements apply to the new and replaeed Yes hard surfaces and converted vegetation areas_ All Minimum Requirements apply to the new hard surfac:cs and converted vegetation areas. No Yes Does the proJecL add 5,000 square feet or No more of new hard surfaces? Yes Do new hard surfaces add 50%ter more to the existing hard surfaces within the project limits? No Noadditional I requirements. Figure 1-4. Flow Chart for Determining Minimum Requirements for Development (Figure 3.1 in the Edmonds Stormwater Addendum). CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section II, Page 1 Section II — Off -Site Analysis Section II Summary Task 1— Define and map the study area Task 2 — Review all available information of the study area Task 3 — Field inspect the area Task 4 - Describe the drainage system, and its existing and predicted problems Task 1— Define and map the study area An initial qualitative analysis shall document potential off -site impacts of stormwater discharges for each upstream drainage system entering a site, and each downstream drainage system leaving a site according to Section 6.2 of the Edmonds Stormwater Addendum. The downstream analysis shall extend from the project site to the receiving water, or up to one -quarter mile, whichever is less. Runoff from the site enters the City's MS4 within one -quarter mile since the project proposes to connect into the public storm main along the project frontage. The receiving water is Perrinville Creek which is about 0.10 mi downstream from the site. The downstream flowpath is outlined below in Figure II-1 from the City GIS map. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section II, Page 2 CONNECTION POINT Cp� ?-26 n z n PROJECT SITE PERRINVILLE CREEK s� -2$ 22 P CO [� P j Creek ►fir ��.r °-ouc 00 00 41 } Cd -? 4 f Figure II-1. Map showing stormwater flow path and distance from site to outfall. Task 2 — Review all available information on the study area Existing stormwater improvements were determined from the survey and the City GIS map. There is a 12" HDPE pipe that runs west across the north frontage of the site. The pipe reaches a catch basin, is converted to 12" concrete, and is conveyed west along Talbot Rd as it bends south. The 12" concrete pipe discharges to a 30" concrete culvert going east to west under Talbot road which outfalls in the Perrinville Creek. Per the City GIS map, the south end of the site contains potential erosion/landslide hazard areas. A hazard area map can be found below in Figure II-2. The steep slopes as shown on the map are located at the southern half of the site, and runoff from these areas would discharge into the Perrinville Creek. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section II, Page 3 k -in IN Z oro 1 PROJECT SITE C Figure II-2. Erosion hazard area map. I Task 3 — Field inspect the study area A site visit was done on the afternoon on January 27, 2021. The weather was partly cloudy, and it had rained lightly earlier in the day. From evaluating surrounding conditions, the site appears to take on upstream runoff into the existing driveway from Cyrus PI to the northeast. There is an existing catch basin upstream from the site in the ROW, but it is not collecting all the runoff from Cyrus PI. The project proposes to add a catch basin in the ROW in front of the proposed driveway. Figures II-3 and II-4 below shows the area of upstream runoff from Cyrus PI. Figure II-4 shows the downstream flow path from the site, and Figures II-5 to II-7 show the existing site drainage conditions. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section II, Page 4 Figure II-3. From Talbot Rd looking southwest at the area of upstream runoff. Figure II-4. Northeast corner of the site facing west (downstream). 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section II, Page 5 Figure II-5: On Talbot Rd facing east (upstream) towards Perrinville Creek at the approximate outfall. C 4m ENGINEERING Figure II-6. Existing driveway sloped towards house, causing flooding. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section II, Page 6 Figure II-7. Backyard sloped towards existing house, flooding into window well. Task 4 — Describe the drainage system, and its existing and predicted problems Existing stormwater improvements were determined from the survey, the City GIS map, and the site visit. The existing house has roof gutters with downspouts that either enter a roof drain system or are daylighted above the existing ground. The conveyance path of the existing roof drain system is unknown. The driveway and southern portion of the backyard currently slopes towards the house. The driveway runoff is being contained by a yard drain which is conveyed to a rock area on the east side of the south. This drainage system does not function properly, and there are many areas where stormwater runoff from the driveway flows freely towards the house foundation. Runoff from the backyard flows towards a southwest corner of the house and collects in a window well. There is currently a sump pump inside the window well to prevent flooding, but during times of high rainfall, the pump is unable to handle the amount of runoff, causing flooding. The project proposes to route all runoff from all new/replaced impervious and the existing roof of the site to a 27'x10'x3' infiltration trench to meet on -site stormwater management requirements (see Section III). The system will be tied into a type I catch basin in the ROW with conveyance pipes that run west along Talbot Rd. This catch basin will also receive upstream runoff from Cyrus PI. Footing drains will be added around the perimeter of the house to prevent further flooding and erosion around the building foundation. The footing drains will overflow into the storm main in the ROW. Catch basins will be installed throughout the site to collect runoff from impervious areas and route stormwater to the infiltration trench. No problems are expected to arise as long as the stormwater BMPs proposed are installed and maintained properly. CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section III, Page 1 Section III — Permanent Stormwater Control Plan Section III Summary Narrative WWHM2012 Report AInrrntivo The proposed project is a Category 2 project per the Edmonds Stormwater Addendum that discharges to the City's MS4. It shall either use On -Site Stormwater Management BMPs from List No. 2 (per ECDC 18.30.060.D.5.e) for all new plus replaced hard surfaces and land disturbed, or demonstrate compliance with the LID performance standard (per ECDC 18.30.060.D.5.c ). The project proposes to demonstrate compliance with the LID performance standard by using a 27' x 10' x 3' infiltration trench. See the WWHM report below. The design includes all impervious surfaces onsite (existing unmanaged, new and replaced) in order to account for the City of Edmonds on site stormwater management retrofit requirement. Per the property account summary from Snohomish County's parcel data, the existing residence was constructed in 1954. It is therefore assumed that the existing condition and the pre-1977 condition of the property are essentially the same. As a result, flow control is not required for the project since the development does not cause a 0.15 cubic feet per second (cfs) increase or greater in the 100-year flow frequency from a threshold discharge area as estimated using the Western Washington Hydrology Model or other approved model with 15-minute time steps. See the WWHM report below. Runoff treatment is also not required for this project (see Minimum Requirements #6 & #7 in Section 1). 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT Project Name: Hill Residence LID Infiltration Trench 05.17.21 Site Name: Site Address: City Report Date: 5/17/2021 MGS Regoin Puget East Data Start 1901/10/1 Data End : 2058/09/30 DOT Data Number: 03 Version Date: 2019/09/13 Version : 4.2.17 Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .28 Pervious Total 0.28 Impervious Land Use acre Impervious Total 0 Basin Total 0.28 Element Flows To: Surface MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Interflow Groundwater Pervious Land Use acre Pervious Total Impervious Land Use ROOF TOPS FLAT DRIVEWAYS FLAT SIDEWALKS FLAT Impervious Total Basin Total Element Flows To: Surface Gravel Trench Bed 1 F acre 0.09 0.09 0.1 0.28 0.28 Interflow Groundwater Gravel Trench Bed 1 Name : Gravel Trench Bed 1 Bottom Length: 27.00 ft. Bottom Width: 10.00 ft. Trench bottom slope 1: 0 To 1 Trench Left side slope 0: 0 To 1 Trench right side slope 2: 0 To 1 Material thickness of first layer: 3 Pour Space of material for first layer: 0.33 Material thickness of second layer: 0 Pour Space of material for second layer: 0 Material thickness of third layer: 0 Pour Space of material for third layer: 0 Infiltration On Infiltration rate: 2.5 Infiltration safety factor: 1 Total Volume Infiltrated (ac-ft.): 102.342 Total Volume Through Riser (ac-ft.): 3.676 Total Volume Through Facility (ac-ft.): 106.018 Percent Infiltrated: 96.53 Total Precip Applied to Facility: 0 Total Evap From Facility: 0 Discharge Structure Riser Height: 2.95 ft. Riser Diameter: 6 in. Element Flows To: Outlet 1 Outlet 2 Gravel Trench Bed Hydraulic Table Stage(feet) Area(ac.) Volume(ac-ft.) Discharge(cfs) Infilt(cfs) 0.0000 0.006 0.000 0.000 0.000 0.0333 0.006 0.000 0.000 0.015 0.0667 0.006 0.000 0.000 0.015 0.1000 0.006 0.000 0.000 0.015 0.1333 0.006 0.000 0.000 0.015 0.1667 0.006 0.000 0.000 0.015 0.2000 0.006 0.000 0.000 0.015 0.2333 0.006 0.000 0.000 0.015 0.2667 0.006 0.000 0.000 0.015 0.3000 0.006 0.000 0.000 0.015 0.3333 0.006 0.000 0.000 0.015 0.3667 0.006 0.000 0.000 0.015 0.4000 0.006 0.000 0.000 0.015 0.4333 0.006 0.000 0.000 0.015 0.4667 0.006 0.001 0.000 0.015 0.5000 0.006 0.001 0.000 0.015 0.5333 0.006 0.001 0.000 0.015 0.5667 0.006 0.001 0.000 0.015 0.6000 0.006 0.001 0.000 0.015 0.6333 0.006 0.001 0.000 0.015 0.6667 0.006 0.001 0.000 0.015 0.7000 0.006 0.001 0.000 0.015 0.7333 0.006 0.001 0.000 0.015 0.7667 0.006 0.001 0.000 0.015 0.8000 0.006 0.001 0.000 0.015 0.8333 0.006 0.001 0.000 0.015 0.8667 0.006 0.001 0.000 0.015 0.9000 0.006 0.001 0.000 0.015 0.9333 0.006 0.001 0.000 0.015 0.9667 0.006 0.002 0.000 0.015 1.0000 0.006 0.002 0.000 0.015 1.0333 0.006 0.002 0.000 0.015 1.0667 0.006 0.002 0.000 0.015 1.1000 0.006 0.002 0.000 0.015 1.1333 0.006 0.002 0.000 0.015 1.1667 0.006 0.002 0.000 0.015 1.2000 0.006 0.002 0.000 0.015 1.2333 0.006 0.002 0.000 0.015 1.2667 0.006 0.002 0.000 0.015 1.3000 0.006 0.002 0.000 0.015 1.3333 0.006 0.002 0.000 0.015 1.3667 0.006 0.002 0.000 0.015 1.4000 0.006 0.002 0.000 0.015 1.4333 0.006 0.002 0.000 0.015 1.4667 0.006 0.003 0.000 0.015 1.5000 0.006 0.003 0.000 0.015 1.5333 0.006 0.003 0.000 0.015 1.5667 0.006 0.003 0.000 0.015 1.6000 0.006 0.003 0.000 0.015 1.6333 0.006 0.003 0.000 0.015 1.6667 0.006 0.003 0.000 0.015 1.7000 0.006 0.003 0.000 0.015 1.7333 0.006 0.003 0.000 0.015 1.7667 0.006 0.003 0.000 0.015 1.8000 0.006 0.003 0.000 0.015 1.8333 0.006 0.003 0.000 0.015 1.8667 0.006 0.003 0.000 0.015 1.9000 0.006 0.003 0.000 0.015 1.9333 0.006 0.004 0.000 0.015 1.9667 0.006 0.004 0.000 0.015 2.0000 0.006 0.004 0.000 0.015 2.0333 0.006 0.004 0.000 0.015 2.0667 0.006 0.004 0.000 0.015 2.1000 0.006 0.004 0.000 0.015 2.1333 0.006 0.004 0.000 0.015 2.1667 0.006 0.004 0.000 0.015 2.2000 0.006 0.004 0.000 0.015 2.2333 0.006 0.004 0.000 0.015 2.2667 0.006 0.004 0.000 0.015 2.3000 0.006 0.004 0.000 0.015 2.3333 0.006 0.004 0.000 0.015 2.3667 0.006 0.004 0.000 0.015 2.4000 0.006 0.004 0.000 0.015 2.4333 0.006 0.005 0.000 0.015 2.4667 0.006 0.005 0.000 0.015 2.5000 0.006 0.005 0.000 0.015 2.5333 0.006 0.005 0.000 0.015 2.5667 0.006 0.005 0.000 0.015 2.6000 0.006 0.005 0.000 0.015 2.6333 0.006 0.005 0.000 0.015 2.6667 0.006 0.005 0.000 0.015 2.7000 0.006 0.005 0.000 0.015 2.7333 0.006 0.005 0.000 0.015 2.7667 0.006 0.005 0.000 0.015 2.8000 0.006 0.005 0.000 0.015 2.8333 0.006 0.005 0.000 0.015 2.8667 0.006 0.005 0.000 0.015 2.9000 0.006 0.005 0.000 0.015 2.9333 0.006 0.006 0.000 0.015 2.9667 0.006 0.006 0.011 0.015 3.0000 0.006 0.006 0.059 0.015 ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.28 Total Impervious Area:O Mitigated Landuse Totals for POC #1 Total Pervious Area:O Total Impervious Area:0.28 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.000053 5 year 0.000059 10 year 25 year 50 year 100 year Flow Frequency Return Return Period 2 year 5 year 10 year 25 year 50 year 100 year 0.000062 0.000064 0.000065 0.000066 Periods for Mitigated Flow(cfs) 0.046567 0.074363 0.089733 0.10553 0.114984 0.122791 Stream Protection Duration Annual Peaks for Predeveloped and Mitigated Year Predeveloped Mitigated 1902 0.000 0.036 1903 0.000 0.042 1904 0.000 0.046 1905 0.000 0.016 1906 0.000 0.018 1907 0.000 0.053 1908 0.000 0.036 1909 0.000 0.027 1910 0.000 0.055 1911 0.000 0.037 1912 0.000 0.107 1913 0.000 0.027 1914 0.000 0.090 1915 0.000 0.007 1916 0.000 0.051 1917 0.000 0.032 1918 0.000 0.022 1919 0.000 0.024 1920 0.000 0.034 1921 0.000 0.012 1922 0.000 0.045 1923 0.000 0.021 1924 0.000 0.021 1925 0.000 0.000 1926 0.000 0.035 1927 0.000 0.029 1928 0.000 0.028 1929 0.000 0.052 1930 0.000 0.038 1931 0.000 0.032 1932 0.000 0.039 1933 0.000 0.026 1934 0.000 0.069 1935 0.000 0.019 1936 0.000 0.026 1937 0.000 0.054 1938 0.000 0.025 1939 0.000 0.016 1940 0.000 0.077 POC #1 POC #1 1941 0.000 0.052 1942 0.000 0.050 1943 0.000 0.046 1944 0.000 0.107 1945 0.000 0.064 1946 0.000 0.020 1947 0.000 0.038 1948 0.000 0.055 1949 0.000 0.055 1950 0.000 0.015 1951 0.000 0.021 1952 0.000 0.104 1953 0.000 0.098 1954 0.000 0.035 1955 0.000 0.020 1956 0.000 0.000 1957 0.000 0.023 1958 0.000 0.058 1959 0.000 0.028 1960 0.000 0.016 1961 0.000 0.128 1962 0.000 0.045 1963 0.000 0.003 1964 0.000 0.066 1965 0.000 0.049 1966 0.000 0.000 1967 0.000 0.017 1968 0.000 0.019 1969 0.000 0.027 1970 0.000 0.045 1971 0.000 0.061 1972 0.000 0.130 1973 0.000 0.052 1974 0.000 0.041 1975 0.000 0.088 1976 0.000 0.068 1977 0.000 0.014 1978 0.000 0.063 1979 0.000 0.018 1980 0.000 0.021 1981 0.000 0.036 1982 0.000 0.000 1983 0.000 0.051 1984 0.000 0.056 1985 0.000 0.029 1986 0.000 0.021 1987 0.000 0.045 1988 0.000 0.029 1989 0.000 0.027 1990 0.000 0.028 1991 0.000 0.068 1992 0.000 0.073 1993 0.000 0.046 1994 0.000 0.040 1995 0.000 0.000 1996 0.000 0.036 1997 0.000 0.025 1998 0.000 0.053 1999 0.000 0.016 2000 0.000 0.054 2001 0.000 0.026 2002 0.000 0.057 2003 0.000 0.038 2004 0.000 0.044 2005 0.000 0.063 2006 0.000 0.010 2007 0.000 0.062 2008 0.000 0.022 2009 0.000 0.032 2010 0.000 0.062 2011 0.000 0.002 2012 0.000 0.062 2013 0.000 0.014 2014 0.000 0.018 2015 0.000 0.054 2016 0.000 0.000 2017 0.000 0.095 2018 0.000 0.059 2019 0.000 0.078 2020 0.000 0.032 2021 0.000 0.061 2022 0.000 0.045 2023 0.000 0.025 2024 0.000 0.127 2025 0.000 0.017 2026 0.000 0.041 2027 0.000 0.040 2028 0.000 0.000 2029 0.000 0.028 2030 0.000 0.056 2031 0.000 0.010 2032 0.000 0.002 2033 0.000 0.000 2034 0.000 0.024 2035 0.000 0.056 2036 0.000 0.029 2037 0.000 0.024 2038 0.000 0.056 2039 0.000 0.029 2040 0.000 0.043 2041 0.000 0.039 2042 0.000 0.069 2043 0.000 0.061 2044 0.000 0.030 2045 0.000 0.022 2046 0.000 0.034 2047 0.000 0.046 2048 0.000 0.049 2049 0.000 0.057 2050 0.000 0.038 2051 0.000 0.080 2052 0.000 0.025 2053 0.000 0.027 2054 0.000 0.075 2055 0.000 0.017 2056 0.000 0.031 2057 0.000 0.022 2058 0.000 0.030 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0001 0.1301 2 0.0001 0.1276 3 0.0001 0.1268 4 0.0001 0.1074 5 0.0001 0.1065 6 0.0001 0.1036 7 0.0001 0.0983 8 0.0001 0.0952 9 0.0001 0.0901 10 0.0001 0.0877 11 0.0001 0.0804 12 0.0001 0.0785 13 0.0001 0.0772 14 0.0001 0.0750 15 0.0001 0.0733 16 0.0001 0.0686 17 0.0001 0.0686 18 0.0001 0.0684 19 0.0001 0.0681 20 0.0001 0.0657 21 0.0001 0.0641 22 0.0001 0.0633 23 0.0001 0.0628 24 0.0001 0.0619 25 0.0001 0.0616 26 0.0001 0.0615 27 0.0001 0.0612 28 0.0001 0.0610 29 0.0001 0.0606 30 0.0001 0.0594 31 0.0001 0.0584 32 0.0001 0.0572 33 0.0001 0.0565 34 0.0001 0.0563 35 0.0001 0.0557 36 0.0001 0.0557 37 0.0001 0.0557 38 0.0001 0.0554 39 0.0001 0.0553 40 0.0001 0.0551 41 0.0001 0.0542 42 0.0001 0.0542 43 0.0001 0.0537 44 0.0001 0.0533 45 0.0001 0.0531 46 0.0001 0.0523 47 0.0001 0.0516 48 0.0001 0.0515 49 0.0001 0.0512 50 0.0001 0.0508 51 0.0001 0.0500 52 0.0001 0.0494 53 0.0001 0.0493 54 0.0001 0.0464 55 0.0001 0.0463 56 0.0001 0.0461 57 0.0001 0.0461 58 0.0001 0.0453 59 0.0001 0.0452 60 0.0001 0.0449 61 0.0001 0.0447 62 0.0001 0.0447 63 0.0001 0.0440 64 0.0001 0.0429 65 0.0001 0.0417 66 0.0001 0.0414 67 0.0001 0.0413 68 0.0001 0.0396 69 0.0001 0.0396 70 0.0001 0.0391 71 0.0001 0.0385 72 0.0001 0.0383 73 0.0001 0.0383 74 0.0001 0.0381 75 0.0001 0.0377 76 0.0001 0.0367 77 0.0001 0.0365 78 0.0001 0.0364 79 0.0001 0.0360 80 0.0001 0.0356 81 0.0001 0.0351 82 0.0001 0.0351 83 0.0001 0.0340 84 0.0001 0.0337 85 0.0001 0.0325 86 0.0001 0.0316 87 0.0001 0.0316 88 0.0001 0.0316 89 0.0001 0.0313 90 0.0001 0.0303 91 0.0001 0.0303 92 0.0001 0.0293 93 0.0001 0.0293 94 0.0001 0.0289 95 0.0001 0.0287 96 0.0001 0.0286 97 0.0001 0.0284 98 0.0001 0.0280 99 0.0001 0.0276 100 0.0001 0.0276 101 0.0001 0.0273 102 0.0001 0.0272 103 0.0001 0.0270 104 0.0001 0.0268 105 0.0001 0.0267 106 0.0001 0.0262 107 0.0001 0.0261 108 0.0001 0.0257 109 0.0001 0.0250 110 0.0001 0.0250 111 0.0001 0.0250 112 0.0001 0.0246 113 0.0001 0.0243 114 0.0001 0.0241 115 0.0001 0.0237 116 0.0001 0.0232 117 0.0001 0.0225 118 0.0001 0.0223 119 0.0001 0.0223 120 0.0001 0.0217 121 0.0000 0.0214 122 0.0000 0.0213 123 0.0000 0.0211 124 0.0000 0.0210 125 0.0000 0.0208 126 0.0000 0.0198 127 0.0000 0.0196 128 0.0000 0.0194 129 0.0000 0.0194 130 0.0000 0.0183 131 0.0000 0.0180 132 0.0000 0.0176 133 0.0000 0.0174 134 0.0000 0.0172 135 0.0000 0.0165 136 0.0000 0.0165 137 0.0000 0.0164 138 0.0000 0.0158 139 0.0000 0.0157 140 0.0000 0.0154 141 0.0000 0.0139 142 0.0000 0.0137 143 0.0000 0.0125 144 0.0000 0.0104 145 0.0000 0.0102 146 0.0000 0.0070 147 0.0000 0.0035 148 0.0000 0.0021 149 0.0000 0.0017 150 0.0000 0.0000 151 0.0000 0.0000 152 0.0000 0.0000 153 0.0000 0.0000 154 0.0000 0.0000 155 0.0000 0.0000 156 0.0000 0.0000 157 0.0000 0.0000 LID Duration LID Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1902 0.000 0.036 1903 0.000 0.042 1904 0.000 0.046 1905 0.000 0.016 1906 0.000 0.018 1907 0.000 0.053 1908 0.000 0.036 1909 0.000 0.027 1910 0.000 0.055 1911 0.000 0.037 1912 0.000 0.107 1913 0.000 0.027 1914 0.000 0.090 1915 0.000 0.007 1916 0.000 0.051 1917 0.000 0.032 1918 0.000 0.022 1919 0.000 0.024 1920 0.000 0.034 1921 0.000 0.012 1922 0.000 0.045 1923 0.000 0.021 1924 0.000 0.021 1925 0.000 0.000 1926 0.000 0.035 1927 0.000 0.029 1928 0.000 0.028 1929 0.000 0.052 1930 0.000 0.038 1931 0.000 0.032 1932 0.000 0.039 1933 0.000 0.026 1934 0.000 0.069 1935 0.000 0.019 1936 0.000 0.026 1937 0.000 0.054 1938 0.000 0.025 1939 0.000 0.016 1940 0.000 0.077 1941 0.000 0.052 1942 0.000 0.050 1943 0.000 0.046 1944 0.000 0.107 1945 0.000 0.064 1946 0.000 0.020 1947 0.000 0.038 1948 0.000 0.055 1949 0.000 0.055 1950 0.000 0.015 1951 0.000 0.021 1952 0.000 0.104 1953 0.000 0.098 1954 0.000 0.035 1955 0.000 0.020 1956 0.000 0.000 1957 0.000 0.023 1958 0.000 0.058 1959 0.000 0.028 1960 0.000 0.016 1961 0.000 0.128 1962 0.000 0.045 1963 0.000 0.003 1964 0.000 0.066 1965 0.000 0.049 1966 0.000 0.000 1967 0.000 0.017 1968 0.000 0.019 1969 0.000 0.027 1970 0.000 0.045 1971 0.000 0.061 1972 0.000 0.130 1973 0.000 0.052 1974 0.000 0.041 1975 0.000 0.088 1976 0.000 0.068 1977 0.000 0.014 1978 0.000 0.063 1979 0.000 0.018 1980 0.000 0.021 1981 0.000 0.036 1982 0.000 0.000 1983 0.000 0.051 1984 0.000 0.056 1985 0.000 0.029 1986 0.000 0.021 1987 0.000 0.045 1988 0.000 0.029 1989 0.000 0.027 1990 0.000 0.028 1991 0.000 0.068 1992 0.000 0.073 1993 0.000 0.046 1994 0.000 0.040 1995 0.000 0.000 1996 0.000 0.036 1997 0.000 0.025 1998 0.000 0.053 1999 0.000 0.016 2000 0.000 0.054 2001 0.000 0.026 2002 0.000 0.057 2003 0.000 0.038 2004 0.000 0.044 2005 0.000 0.063 2006 0.000 0.010 2007 0.000 0.062 2008 0.000 0.022 2009 0.000 0.032 2010 0.000 0.062 2011 0.000 0.002 2012 0.000 0.062 2013 0.000 0.014 2014 0.000 0.018 2015 0.000 0.054 2016 0.000 0.000 2017 0.000 0.095 2018 0.000 0.059 2019 0.000 0.078 2020 0.000 0.032 2021 0.000 0.061 2022 0.000 0.045 2023 0.000 0.025 2024 0.000 0.127 2025 0.000 0.017 2026 0.000 0.041 2027 0.000 0.040 2028 0.000 0.000 2029 0.000 0.028 2030 0.000 0.056 2031 0.000 0.010 2032 0.000 0.002 2033 0.000 0.000 2034 0.000 0.024 2035 0.000 0.056 2036 0.000 0.029 2037 0.000 0.024 2038 0.000 0.056 2039 0.000 0.029 2040 0.000 0.043 2041 0.000 0.039 2042 0.000 0.069 2043 0.000 0.061 2044 0.000 0.030 2045 0.000 0.022 2046 0.000 0.034 2047 0.000 0.046 2048 0.000 0.049 2049 0.000 0.057 2050 0.000 0.038 2051 0.000 0.080 2052 0.000 0.025 2053 0.000 0.027 2054 0.000 0.075 2055 0.000 0.017 2056 0.000 0.031 2057 0.000 0.022 2058 0.000 0.030 LID Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0001 0.1301 2 0.0001 0.1276 3 0.0001 0.1268 4 0.0001 0.1074 5 0.0001 0.1065 6 0.0001 0.1036 7 0.0001 0.0983 8 0.0001 0.0952 9 0.0001 0.0901 10 0.0001 0.0877 11 0.0001 0.0804 12 0.0001 0.0785 13 0.0001 0.0772 14 0.0001 0.0750 15 0.0001 0.0733 16 0.0001 0.0686 17 0.0001 0.0686 18 0.0001 0.0684 19 0.0001 0.0681 20 0.0001 0.0657 21 0.0001 0.0641 22 0.0001 0.0633 23 0.0001 0.0628 24 0.0001 0.0619 25 0.0001 0.0616 26 0.0001 0.0615 27 0.0001 0.0612 28 0.0001 0.0610 29 0.0001 0.0606 30 0.0001 0.0594 31 0.0001 0.0584 32 0.0001 0.0572 33 0.0001 0.0565 34 0.0001 0.0563 35 0.0001 0.0557 36 0.0001 0.0557 37 0.0001 0.0557 38 0.0001 0.0554 39 0.0001 0.0553 40 0.0001 0.0551 41 0.0001 0.0542 42 0.0001 0.0542 43 0.0001 0.0537 44 0.0001 0.0533 45 0.0001 0.0531 46 0.0001 0.0523 47 0.0001 0.0516 48 0.0001 0.0515 49 0.0001 0.0512 50 0.0001 0.0508 51 0.0001 0.0500 52 0.0001 0.0494 53 0.0001 0.0493 54 0.0001 0.0464 55 0.0001 0.0463 56 0.0001 0.0461 57 0.0001 0.0461 58 0.0001 0.0453 59 0.0001 0.0452 60 0.0001 0.0449 61 0.0001 0.0447 62 0.0001 0.0447 63 0.0001 0.0440 64 0.0001 0.0429 65 0.0001 0.0417 66 0.0001 0.0414 67 0.0001 0.0413 68 0.0001 0.0396 69 0.0001 0.0396 70 0.0001 0.0391 71 0.0001 0.0385 72 0.0001 0.0383 73 0.0001 0.0383 74 0.0001 0.0381 75 0.0001 0.0377 76 0.0001 0.0367 77 0.0001 0.0365 78 0.0001 0.0364 79 0.0001 0.0360 80 0.0001 0.0356 81 0.0001 0.0351 82 0.0001 0.0351 83 0.0001 0.0340 84 0.0001 0.0337 85 0.0001 0.0325 86 0.0001 0.0316 87 0.0001 0.0316 88 0.0001 0.0316 89 0.0001 0.0313 90 0.0001 0.0303 91 0.0001 0.0303 92 0.0001 0.0293 93 0.0001 0.0293 94 0.0001 0.0289 95 0.0001 0.0287 96 0.0001 0.0286 97 0.0001 0.0284 98 0.0001 0.0280 99 0.0001 0.0276 100 0.0001 0.0276 101 0.0001 0.0273 102 0.0001 0.0272 103 0.0001 0.0270 104 0.0001 0.0268 105 0.0001 0.0267 106 0.0001 0.0262 107 0.0001 0.0261 108 0.0001 0.0257 109 0.0001 0.0250 110 0.0001 0.0250 111 0.0001 0.0250 112 0.0001 0.0246 113 0.0001 0.0243 114 0.0001 0.0241 115 0.0001 0.0237 116 0.0001 0.0232 117 0.0001 0.0225 118 0.0001 0.0223 119 0.0001 0.0223 120 0.0001 0.0217 121 0.0000 0.0214 122 0.0000 0.0213 123 0.0000 0.0211 124 0.0000 0.0210 125 0.0000 0.0208 126 0.0000 0.0198 127 0.0000 0.0196 128 0.0000 0.0194 129 0.0000 0.0194 130 0.0000 0.0183 131 0.0000 0.0180 132 0.0000 0.0176 133 0.0000 0.0174 134 0.0000 0.0172 135 0.0000 0.0165 136 0.0000 0.0165 137 0.0000 0.0164 138 0.0000 0.0158 139 0.0000 0.0157 140 0.0000 0.0154 141 0.0000 0.0139 142 0.0000 0.0137 143 0.0000 0.0125 144 0.0000 0.0104 145 0.0000 0.0102 146 0.0000 0.0070 147 0.0000 0.0035 148 0.0000 0.0021 149 0.0000 0.0017 150 0.0000 0.0000 151 0.0000 0.0000 152 0.0000 0.0000 153 0.0000 0.0000 154 0.0000 0.0000 155 0.0000 0.0000 156 0.0000 0.0000 157 0.0000 0.0000 LID Duration POC #1 The Facility PASSED The Facility PASSED. Flow(cfs) Predev Mit Percentage Pass/Fail 0.0000 25268 2882 11 Pass 0.0000 24470 2882 11 Pass 0.0000 23740 2882 12 Pass 0.0000 22791 2882 12 Pass 0.0000 22103 2882 13 Pass 0.0000 21401 2882 13 Pass 0.0000 20754 2882 13 Pass 0.0000 19846 2882 14 Pass 0.0000 19295 2882 14 Pass 0.0000 18745 2882 15 Pass 0.0000 18290 2882 15 Pass 0.0000 17616 2882 16 Pass 0.0000 17148 2882 16 Pass 0.0000 16749 2882 17 Pass 0.0000 16405 2882 17 Pass 0.0000 15799 2882 18 Pass 0.0000 15414 2882 18 Pass 0.0000 15084 2882 19 Pass 0.0000 14753 2882 19 Pass 0.0000 14244 2882 20 Pass 0.0000 13928 2882 20 Pass 0.0000 13600 2882 21 Pass 0.0000 13339 2882 21 Pass 0.0000 12913 2882 22 Pass 0.0000 12613 2882 22 Pass 0.0000 12308 2882 23 Pass 0.0000 12033 2882 23 Pass 0.0000 11665 2882 24 Pass 0.0000 11426 2882 25 Pass 0.0000 11199 2882 25 Pass 0.0000 10984 2882 26 Pass 0.0000 10659 2882 27 Pass 0.0000 10454 2882 27 Pass 0.0000 10239 2882 28 Pass 0.0000 10036 2882 28 Pass 0.0000 9732 2882 29 Pass 0.0000 9554 2882 30 Pass 0.0000 9393 2882 30 Pass 0.0000 9242 2882 31 Pass 0.0000 8999 2882 32 Pass 0.0000 8822 2882 32 Pass 0.0000 8643 2882 33 Pass 0.0000 8465 2882 34 Pass 0.0000 8251 2882 34 Pass 0.0000 8099 2882 35 Pass 0.0000 7956 2882 36 Pass 0.0000 7827 2882 36 Pass 0.0000 7633 2882 37 Pass 0.0000 7495 2882 38 Pass 0.0000 7357 2882 39 Pass 0.0000 7243 2882 39 Pass 0.0000 7062 2882 40 Pass 0.0000 6956 2882 41 Pass 0.0000 6847 2882 42 Pass 0.0000 6746 2882 42 Pass 0.0000 6590 2882 43 Pass 0.0000 6492 2882 44 Pass 0.0000 6387 2882 45 Pass 0.0000 6274 2882 45 Pass 0.0000 6123 2882 47 Pass 0.0000 6025 2882 47 Pass 0.0000 5944 2882 48 Pass 0.0000 5848 2882 49 Pass 0.0000 5705 2882 50 Pass 0.0000 5605 2882 51 Pass 0.0000 5513 2882 52 Pass 0.0000 5432 2882 53 Pass 0.0000 5307 2882 54 Pass 0.0000 5231 2882 55 Pass 0.0000 5164 2882 55 Pass 0.0000 5074 2882 56 Pass 0.0000 4959 2882 58 Pass 0.0000 4883 2882 59 Pass 0.0000 4809 2882 59 Pass 0.0000 4744 2882 60 Pass 0.0000 4648 2882 62 Pass 0.0000 4577 2882 62 Pass 0.0000 4507 2882 63 Pass 0.0000 4438 2882 64 Pass 0.0000 4345 2882 66 Pass 0.0000 4272 2882 67 Pass 0.0000 4198 2882 68 Pass 0.0000 4140 2882 69 Pass 0.0000 4037 2882 71 Pass 0.0000 3983 2882 72 Pass 0.0000 3920 2882 73 Pass 0.0000 3859 2882 74 Pass 0.0000 3774 2882 76 Pass 0.0000 3723 2882 77 Pass 0.0000 3681 2882 78 Pass 0.0000 3633 2882 79 Pass 0.0000 3562 2882 80 Pass 0.0000 3508 2882 82 Pass 0.0000 3454 2882 83 Pass 0.0000 3412 2881 84 Pass 0.0000 3348 2881 86 Pass 0.0000 3302 2881 87 Pass 0.0000 3249 2881 88 Pass 0.0000 3205 2881 89 Pass 0.0000 3135 2881 91 Pass Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Gravel Trench Bed 1 POC N 96.48 N 96.53 Total Volume Infiltrated 96.48 0.00 0.00 96.53 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Passed Perind and Impind Changes No changes have been made. This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2021; All Rights Reserved. WWHM2012 PROJECT REPORT Project Name: Hill Residence Flow Control Check 06.02.21 Site Name: Site Address: City Report Date: 6/2/2021 MGS Regoin Puget East Data Start 1901/10/1 Data End : 2058/09/30 DOT Data Number: 03 Version Date: 2019/09/13 Version : 4.2.17 Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : Basin 1 Bypass: No GroundWater: No Pervious Land Use acre A B, Forest, Flat .05 Pervious Total 0.05 Impervious Land Use acre ROOF TOPS FLAT 0.09 DRIVEWAYS FLAT 0.11 SIDEWALKS FLAT 0.03 Impervious Total 0.23 Basin Total 0.28 Element Flows To: Surface MITIGATED LAND USE Name : Basin 1 Bypass: No Interflow Groundwater Groundwater: No Pervious Land Use acre Pervious Total 0 Impervious Land Use acre ROOF TOPS FLAT 0.09 DRIVEWAYS FLAT 0.09 SIDEWALKS FLAT 0.1 Impervious Total 0.28 Basin Total 0.28 Element Flows To: Surface Interflow ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.05 Total Impervious Area:0.23 Mitigated Landuse Totals for POC #1 Total Pervious Area:O Total Impervious Area:0.28 Groundwater Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.057195 5 year 0.075423 10 year 0.08849 25 year 0.106178 50 year 0.120236 100 year 0.135073 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.069626 5 year 0.091816 10 year 0.107724 25 year 0.129258 50 year 0.146373 100 year 0.164435 Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1902 0.064 0.077 1903 0.071 0.087 1904 0.080 0.098 1905 0.038 0.046 1906 0.042 0.051 1907 0.057 0.070 1908 0.051 0.062 1909 0.065 0.080 1910 0.058 0.071 1911 0.062 0.076 1912 0.101 0.123 1913 0.037 0.046 1914 0.146 0.178 1915 0.039 0.048 1916 0.062 0.076 1917 0.038 0.047 1918 0.057 0.069 1919 0.034 0.041 1920 0.049 0.060 1921 0.036 0.044 1922 0.050 0.061 1923 0.053 0.064 1924 0.068 0.083 1925 0.037 0.045 1926 0.072 0.088 1927 0.051 0.063 1928 0.047 0.057 1929 0.078 0.095 1930 0.089 0.108 1931 0.041 0.049 1932 0.047 0.057 1933 0.045 0.054 1934 0.070 0.085 1935 0.043 0.052 1936 0.045 0.055 1937 0.064 0.078 1938 0.042 0.052 1939 0.059 0.072 1940 0.081 0.098 1941 0.068 0.083 1942 0.062 0.076 1943 0.071 0.086 1944 0.103 0.126 1945 0.070 0.086 1946 0.049 0.060 1947 0.045 0.055 1948 0.057 0.069 1949 0.092 0.112 1950 0.039 0.047 1951 0.061 0.074 1952 0.098 0.120 1953 0.095 0.116 1954 0.051 0.061 1955 0.044 0.053 1956 0.035 0.042 1957 0.050 0.061 1958 0.062 0.075 1959 0.059 0.072 1960 0.049 0.060 1961 0.139 0.169 1962 0.055 0.068 1963 0.038 0.047 1964 0.100 0.121 1965 0.060 0.073 1966 0.046 0.056 1967 0.051 0.062 1968 0.046 0.056 1969 0.051 0.062 1970 0.060 0.073 1971 0.062 0.076 1972 0.181 0.221 1973 0.101 0.123 1974 0.077 0.093 1975 0.087 0.106 1976 0.075 0.091 1977 0.035 0.042 1978 0.064 0.078 1979 0.058 0.071 1980 0.057 0.069 1981 0.065 0.080 1982 0.047 0.057 1983 0.066 0.081 1984 0.062 0.076 1985 0.060 0.073 1986 0.040 0.049 1987 0.064 0.078 1988 0.043 0.052 1989 0.041 0.050 1990 0.044 0.053 1991 0.071 0.086 1992 0.071 0.086 1993 0.083 0.101 1994 0.053 0.065 1995 0.038 0.046 1996 0.055 0.068 1997 0.046 0.056 1998 0.059 0.071 1999 0.065 0.079 2000 0.065 0.079 2001 0.059 0.072 2002 0.084 0.102 2003 0.044 0.054 2004 0.075 0.092 2005 0.109 0.133 2006 0.048 0.058 2007 0.067 0.081 2008 0.053 0.064 2009 0.050 0.061 2010 0.063 0.076 2011 0.043 0.052 2012 0.063 0.077 2013 0.047 0.057 2014 0.051 0.062 2015 0.087 0.106 2016 0.041 0.050 2017 0.093 0.113 2018 0.061 0.074 2019 0.080 0.098 2020 0.068 0.083 2021 0.064 0.077 2022 0.082 0.100 2023 0.090 0.109 2024 0.119 0.145 2025 0.049 0.059 2026 0.055 0.067 2027 0.065 0.079 2028 0.030 0.037 2029 0.048 0.059 2030 0.074 0.091 2031 0.035 0.042 2032 0.041 0.049 2033 0.044 0.053 2034 0.047 0.057 2035 0.062 0.075 2036 0.044 0.053 2037 0.062 0.075 2038 0.059 0.072 2039 0.096 0.117 2040 0.049 0.060 2041 0.057 0.069 2042 0.067 0.082 2043 0.076 0.093 2044 0.052 0.063 2045 0.048 0.059 2046 0.047 0.057 2047 0.064 0.078 2048 0.053 0.064 2049 0.079 0.096 2050 0.048 0.059 2051 0.080 0.097 2052 0.050 0.061 2053 0.053 0.064 2054 0.080 0.098 2055 0.051 0.062 2056 0.067 0.081 2057 0.040 0.049 2058 0.073 0.088 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.1812 0.2205 2 0.1459 0.1777 3 0.1386 0.1688 4 0.1195 0.1455 5 0.1091 0.1328 6 0.1035 0.1260 7 0.1011 0.1231 8 0.1010 0.1230 9 0.0997 0.1214 10 0.0983 0.1197 11 0.0962 0.1172 12 0.0950 0.1157 13 0.0927 0.1128 14 0.0921 0.1121 15 0.0898 0.1093 16 0.0887 0.1079 17 0.0871 0.1061 18 0.0867 0.1055 19 0.0840 0.1023 20 0.0826 0.1006 21 0.0824 0.1003 22 0.0805 0.0981 23 0.0805 0.0979 24 0.0804 0.0979 25 0.0803 0.0978 26 0.0798 0.0972 27 0.0793 0.0965 28 0.0782 0.0951 29 0.0767 0.0933 30 0.0764 0.0929 31 0.0753 0.0917 32 0.0751 0.0915 33 0.0744 0.0905 34 0.0726 0.0884 35 0.0721 0.0878 36 0.0713 0.0868 37 0.0710 0.0865 38 0.0709 0.0863 39 0.0706 0.0860 40 0.0704 0.0857 41 0.0700 0.0852 42 0.0683 0.0832 43 0.0683 0.0832 44 0.0679 0.0826 45 0.0671 0.0816 46 0.0669 0.0815 47 0.0667 0.0812 48 0.0661 0.0805 49 0.0654 0.0797 50 0.0654 0.0796 51 0.0653 0.0795 52 0.0646 0.0787 53 0.0645 0.0786 54 0.0641 0.0781 55 0.0640 0.0779 56 0.0639 0.0777 57 0.0637 0.0775 58 0.0636 0.0774 59 0.0636 0.0774 60 0.0632 0.0770 61 0.0626 0.0762 62 0.0623 0.0759 63 0.0623 0.0759 64 0.0623 0.0758 65 0.0622 0.0757 66 0.0622 0.0757 67 0.0616 0.0750 68 0.0616 0.0750 69 0.0616 0.0750 70 0.0612 0.0745 71 0.0607 0.0738 72 0.0603 0.0734 73 0.0603 0.0734 74 0.0602 0.0733 75 0.0593 0.0722 76 0.0593 0.0722 77 0.0590 0.0718 78 0.0589 0.0717 79 0.0586 0.0714 80 0.0585 0.0712 81 0.0584 0.0711 82 0.0574 0.0698 83 0.0569 0.0693 84 0.0568 0.0692 85 0.0568 0.0691 86 0.0566 0.0689 87 0.0555 0.0675 88 0.0555 0.0675 89 0.0548 0.0667 90 0.0533 0.0649 91 0.0530 0.0645 92 0.0529 0.0644 93 0.0528 0.0643 94 0.0525 0.0640 95 0.0516 0.0628 96 0.0514 0.0626 97 0.0513 0.0624 98 0.0508 0.0618 99 0.0508 0.0618 100 0.0507 0.0618 101 0.0505 0.0615 102 0.0505 0.0615 103 0.0503 0.0613 104 0.0502 0.0611 105 0.0500 0.0608 106 0.0499 0.0607 107 0.0495 0.0602 108 0.0491 0.0598 109 0.0491 0.0598 110 0.0490 0.0596 111 0.0489 0.0595 112 0.0484 0.0590 113 0.0483 0.0588 114 0.0481 0.0586 115 0.0478 0.0582 116 0.0472 0.0574 117 0.0471 0.0573 118 0.0470 0.0573 119 0.0470 0.0572 120 0.0468 0.0570 121 0.0466 0.0567 122 0.0463 0.0564 123 0.0458 0.0558 124 0.0456 0.0555 125 0.0454 0.0553 126 0.0454 0.0553 127 0.0446 0.0543 128 0.0442 0.0538 129 0.0437 0.0532 130 0.0437 0.0532 131 0.0436 0.0531 132 0.0436 0.0530 133 0.0431 0.0525 134 0.0426 0.0518 135 0.0426 0.0518 136 0.0424 0.0516 137 0.0423 0.0515 138 0.0411 0.0500 139 0.0408 0.0497 140 0.0406 0.0494 141 0.0405 0.0493 142 0.0403 0.0491 143 0.0402 0.0490 144 0.0392 0.0477 145 0.0388 0.0473 146 0.0384 0.0468 147 0.0384 0.0468 148 0.0381 0.0464 149 0.0375 0.0457 150 0.0374 0.0455 151 0.0373 0.0454 152 0.0365 0.0444 153 0.0348 0.0424 154 0.0347 0.0422 155 0.0346 0.0421 156 0.0335 0.0408 157 0.0305 0.0371 The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 50% of the flows for the range of the duration analysis. Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0 acre-feet On-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. Off-line facility target flow: 0 cfs. Adjusted for 15 min: 0 cfs. LID Report LID Technique Used for Total Volume Volume Infiltration Cumulative Percent Water Quality Percent Comment Treatment? Needs Through Volume Volume Volume Water Quality Treatment Facility (ac-ft.) Infiltration Infiltrated Treated (ac-ft) (ac-ft) Credit Total Volume Infiltrated 0.00 0.00 0.00 0.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Failed Perind and Impind Changes No changes have been made. This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2021; All Rights Reserved. Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section IV, Page 1 Section IV — Construction Stormwater Pollution Prevention Plan Section IV Summary: Narrative Erosion control details are provided consistent with the City of Edmonds guidelines. Erosion control plan sheets are provided in full size as a part of the civil drawing set. A Construction SWPPP is required by the Edmonds Stormwater Management Code since the project results in 2,000 sf or more of new plus replaced hard surfaces. The completed SWPPP can be found below and in the attached permit submittal documents. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section V, Page 1 Section V — Special Reports and/or Studies Section V Summary: Narrative The following reports are included in this section: 1. Geotechnical Slope Consultation by Quality Geo, PLLC, dated 12/21/2020. 2. Infiltration Addendum by Quality Geo, PLLC, dated 5/16/2021. 3. NRCS Web Soil Survey Soil Resource Report dated 02/11/2021. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com QUALITY T IZI"ti'PED f:l?()'1`];1'11\II'.1I. 1:\I:I\]:1:2ING.$CON6ULTIN6 12/21 /2020 Danielle Hill 8112 Talbot Rd Edmonds, WA Subject: 8112 Talbot Rd - Slope Consultation 8112 Talbot Rd, Edmonds, WA QG Project No.: QG20-082 Dear Ms. Hill: At your request, Quality Geo, PLLC (QG) has completed a preliminary review of the above referenced property's existing site conditions, including site visual reconnaissance, slope analysis, and review of existing geologic literature for the site. The project site consists of a mostly developed residential property comprising a portion of a regional slope. It is our understanding that the client intends to complete various site improvements and additions within an area designated as a potential critical area. QG understands that the client requests a geotechnical consultation to confirm that current conditions are favorable, and to provide any additional and necessary recommendation regarding slope considerations. The following report presents the findings and conclusions of our literature review, addresses feasibility of proposed site development, and provides additional geotechnical recommendations for planning and design intended to reduce the inherent risks associated with site development within a potentially geologically hazardous area. GEOLOGIC LITERATURE REVIEW The Washington Geologic Information Portal (WGIP) maintained by the Department of Natural Resources Division of Geology and Earth Resources provides 1:24,000-scale geologic mapping of the region. The subject site is mapped as Glacial Till (Qgt). Till typically comprises unsorted, sub - angular and highly compacted clay, silt, sand, and gravel deposited directly by glacier ice, varying in thickness from discontinuous layers less than 1-inch thick to more than 30 feet. Soil may be Quality Geo, PLLC Geotechnical Engineering & Consulting Phone: 360-764-8485 1 Web: quality-geo.com I Mail: 420 Golf Club Rd SE, Ste 201, Lacey, WA 98503 8112 Talbot Rd Consult Quality Geo, PLLC 12/21/2020 Project # QG20-082 grey where fresh, and yellowish brown where oxidized. Outwash clay, sand, silt, and gravel may be included. According to the regional -scale interactive map, no deep-seated landslides are known to exist within the site or adjacent vicinity. Available LiDAR imagery of the site did not reveal any obvious or prominent landslide features within the site or immediate vicinity. SITE INVESTIGA TION METHODOLOGY On 12/2/2020 a QG Licensed Geologist visited the site to perform visual reconnaissance of the surface and topographic features of the subject property and its proximal slope. While on site, we conducted site surface explorations for a geologic hazard assessment and site feasibility characterization. Relevant property dimensions and slope topography were documented and mapped at representative intervals as access allowed. Soil conditions were evaluated through local exposures. Salient slope features and existing vegetation were documented in order to assess general site stability as well as observe for signs of local instability of an erosional or subsurface nature currently or in the past. A site region and vicinity maps are provided in Appendix A, and a site plan with typical topographic contours and relevant features is presented in Appendix B. Photos showing general site features are provided in Appendix C. SURFACE OBSERVATION The project site is elongated in shaped, with access to the street at the northern edge, and extending across the creek to the south. The upland site is generally flat. A concrete retaining wall exists approximately 60 feet south of the house, and effectively establishes the crest of the local slope. Slopes descend to the south at approximately 3H:1V for approximately 60 horizontal feet, before steepening at the creek bank to 1 H:1 V within 20 feet of the water. QG performed reconnaissance to observe for and document any indications of surface degradation or large-scale slope instability. No obvious features were observed that would indicate an active or prior deep-seated slope failure, such as headscarps or downslope accumulations. Topography was generally consistent, lacking prevalent oversteepened areas, channelized runout zones, or hummocky deposits. No obvious evidence of rotational or translational failures or major toppling hazards was observed on the slope in the proximity of the potential building footprint. No obvious failure features were observed on adjacent slope areas visible from the subject property during our site visit. 0a 8112 Talbot Rd Consult 12/21/2020 SUBSURFACE CONDITIONS: Quality Geo, PLLC Project # QG20-082 A general characterization of on -site soil units observed through local exposures on site within fallen tree pits. • Cover Soils — Sandy Organic Topsoils (SM): QG encountered an overriding layer of organic rich topsoil over most of the site and slope. • Native Soil — Silty Sand (SM): The dominant native soil both shallow and deep, across the upland and slope, appears to comprise a silty sand, with varying silt content, typically becoming cleaner with depth. These soils more closely resemble a recessional glacial outwash soil rather than a dense glacial till. The native sand was loose nearly throughout, becoming somewhat medium dense with depth. Groundwater elevation is inferred to exist at or near the creek elevation. DISCUSSION & CRITICAL SLOPE RECOMMENDATIONS The findings of QG's site reconnaissance at the subject site do not indicate any excessively prohibitive conditions exist for the site, assuming appropriate site management efforts are maintained. In consideration of the available information, and our direct observations, at this time QG does not consider the site to be within an active deep-seated landslide hazard area. Erosional hazards related to soil creep and saturated soils may be mitigated per the recommendations detailed below to increase slope safety factors. New Slope Retaining Wall Recommendations: At this time, no new dwellings are proposed. Therefore, no foundation setbacks are anticipated to be required to inform site improvements. Small proprietary block walls less than 4 feet in height (measured from bottom of base block to top of wall) typically do not require engineering, and may be suitable for landscape and cosmetic improvements along the upper slopes inclining near 3H:1V. We recommend such a walls base gravel fill section bear on native soils compacted to a firm and unyielding condition, and that they incorporate a drainage course behind the wall, tightlined in accordance with the Drainage Controls section of this report. The wall shall be keyed into a minimum depth that at least spaces the base block 5 horizontal feet from native or newly graded slope face exposure. Block wall construction shall follow the manufactures printed installation instructions. We do not recommend the M 8112 Talbot Rd Consult Quality Geo, PLLC 12/21/2020 Project # QG20-082 construction of block walls greater than 4 feet in height, as the loose native soils are likely to experience settlement due to greater soil loads. Driven Pile Wall Recommendations: QG recommends that any proposed walls that are to be greater than 4 feet in height be designed by a structural engineer. Block and cast -in -place walls may likely experience settlement due to the loose sandy conditions. Such walls would need to bear on piles. The most stable, and economic solution would then be to design any new retaining walls as soldier pile walls, with driven pile supports and lagging between. We recommend the pile embedment and capacities be determined using either the WSDOT Pile Driving Formula, or proprietary formulas provided by the selected pile/hammer company. Actual pile locations, sizing, spacing, and materials shall be determined by the project designer. Except as noted, typical design elements and construction procedures shall be in accordance with manufacturer standards. Any discrepancies encountered that are not addressed herein shall be reconciled by the design engineers during construction. All piles shall be driven to refusal per the manufacturer/installer minimum criteria as determined based on the size of the pile and proposed mechanism of installation. Piles shall be driven straight and plumb, avoiding eccentricity as much as feasible. Piles angled near to or greater than 3 degrees may need to be abandoned. Piles shall be driven to a depth where the pile base is horizontally spaced a minimum of 40 feet from the slope face, in accordance with IBC slope setback requirements. If early pile refusal is encountered, pile acceptance shall be evaluated by the retained inspector in consideration of achieved depth, driving behavior, and adjacent pile conditions. If refusal is encountered at an excessively shallow depth (within upper deposits), QG recommends an alternative driving location be attempted at minimum 3*d (three times pile diameter) and at maximum 5*d on -center from the refused pile. Final acceptance of installed piles shall be at the discretion of the inspector and project engineer. Wall Construction: • Excavations: The duration of time that excavations behind walls remain open should be limited to only as necessary to prepare the base pad and placement of the wall features, backfilling with drain rock and approved fill immediately. Temporary worker protections such as trench boxes or temporary shoring may be required for entering excavations deeper than 4 feet, and all OSHA safety regulations should be observed. Extended open cut periods or work proceeding in wet weather may require surface coverings, lesser cut angles, and/or temporary bracing be applied. 4 8112 Talbot Rd Consult 12/21/2020 Quality Geo, PLLC Project # QG20-082 Shoring may be required to prevent the undermining of nearby existing structures, if excavations are within 5 feet of them, and should be considered by the designer or earthworker as needed. Stockpiling of excavated tailings is to be prohibited above, near, or on slopes. Tailings should be removed to an inland area of the site, sufficiently away from the crest if temporary storage of exported/imported materials is required. • Wall Drainage: To preclude build-up of external hydrostatic pressure, we recommend a minimum width of 1 foot of clean, granular, free -draining material extend from the footing drain at the base of the wall to the ground surface immediately behind the wall. Native soils are not considered suitable as drainage material. Imported wall drain aggregate should conform to WSDOT Standard Specification 9-03.12(4) Gravel Backfill for Drains or 9-03.12(5) Gravel Backfill for Drywells. A filter fabric suitable for use in soil separation and water transmission is recommended to be placed against retained soil cuts behind the wall (if present) to limit migration of fines into the drain corridor. Final parameters shall be determined by the wall designer. • Wall Backfill: Native material is not considered suitable for wall backfill due to its elevated fines content. For additional wall backfills as needed, soils should be relatively granular with less than 5 percent fines (material passing the U.S. No. 200 sieve). QG recommends wall backfill import material to conform to WSDOT Standard Specification 9-03.12(2) Gravel Backfill for Walls. • Wall Backfill Compaction: It is recommended that the upper two feet of wall backfill be compacted to 95 percent of the modified Proctor maximum dry density per ASTM D1557, and 90 percent below that to avoid added pressure on the wall. Wall backfill supporting landscaping elements and other non- structural components should be compacted to a relatively firm and unyielding condition. Site Grading and Permanent Slopes: We recommend that fill placed on slopes steeper than 3H:1V be `benched' in accordance with hillside drives entry of section 2-03.3(14) of the WSDOT Standard Specifications. QG recommends that any new permanent graded slopes be inclined no greater than 3H:1 V at a minimum so as to catch natural topography at the top and toe of the new incline. QG also recommends permanent slopes and undeveloped surfaces be planted with a deep -rooting, rapid - growth vegetative cover as soon as possible after completion of slope construction. Alternatively, slopes may be covered with plastic, straw, etc., until they can be landscaped. Cut or uncontrolled 5 8112 Talbot Rd Consult Quality Geo, PLLC 12/21/2020 Project # QG20-082 fill contaminated with organic or manmade debris are not suitable for reuse as structural or grade fill. Impervious Pavement QG understands the existing driveway is failing in many areas, with potholes, birdbaths, slumps, and cracks. This appears to be due to a combination of 3 factors: lack of proper functioning drainage, lack of a compact base, and presence of relict organic sub soils. The client has requested we offer recommendations for proper replacement of the pavement sections on site. Based on the planned use as a driveway, we assumed relatively low traffic. Table I includes preliminary recommendations for impervious hot -mix asphalt (HMA) pavement and base course thickness for the new roadway. This recommendation assumes that the subgrade will be prepared following the recommendations provided in this report and the traffic assumptions are valid. Table 1: Preliminary Pavement Design Recommendations for Roadway Pavement Layer Type Minimum Thickness, inches Hot -Mix Asphalt 3 WSDOT Spec Base Course 9 These sections should be considered preliminary until the site designer verifies the parameters, traffic loading, and assumed grading are applicable to the final project design. We recommend pavement sections be reviewed by the project designer, who may apply an alternative section for final project use based on the conditions reported herein and final design and construction preferences. Native subsoils shall be free of organic debris and compacted to a firm and unyielding condition prior to the placement of the base course. The main entrance/exit drive will likely experience different traffic volumes than the far end of the pavement areas. As a result, consideration could be given to increasing the pavement section in the main entrance/exit drive. One of the important considerations in designing a high quality and durable pavement is providing adequate drainage. Design of drainage for the proposed pavement section is outside of QG 's scope of work at this time. It is important that bird baths (leeching basins) and surface waves are not created during construction of the HMA layer. A proper slope should also be allowed, and drainage should be provided along the edges of pavements and around catch basins to prevent accumulation of free water within the edges and base course, which otherwise may result in subgrade softening and pavement deterioration under exposure and repeated traffic conditions. 6 8112 Talbot Rd Consult Quality Geo, PLLC 12/21/2020 Project # QG20-082 All pavements require regular maintenance and repair in order to maintain the serviceability of the pavement. These repairs and maintenance are due to normal wear and tear of the pavement surface and are required in order to extend the serviceability life of the pavement. However, after 10 years of service, a normal pavement structure is likely to deteriorate to a point where pavement rehabilitation may be required to maintain the serviceability. The deterioration is more likely if the pavement is constructed over poor subgrade soils or in area of higher traffic volumes. Drainage Controls: During our site visit, it was apparent that there are no functioning site drainage controls. Roof gutters and downspouts are found to outfall directly around the immediate perimeter of the house and pavement. QG is not aware of a dedicated drywell or infiltration basin. While soils on site are generally sandy, it appears that stormwater infiltration is delayed, based on the clients reports of soggy yard conditions. Therefore, inground stormwater infiltration may not be feasible considering the current volumes of stormwater. QG recommends proper drainage controls for stormwater runoff during and after site development to protect the site. The ground surface adjacent to the building should be sloped to drain away from the building pad and slope at a 5% minimum to prevent ponding of water adjacent to the house. Footing drains and yard drains should be incorporated for the building and site design to help maintain a dry yard and building area. QG recommends roof and footing water sources be tightlined (piped) away from the building to an existing catch basin, stormwater system, established channel, or down the slope to be released beyond the base using appropriate energy -dissipating features at the outfall to minimize point erosion. Roof and footing drains should be tightlined separately or should be gathered in an appropriately sized catch basin structure and redistributed collectively. If storm drains are incorporated for impervious flatworks (driveways, patios, etc.), collected waters should also be discharged according to the above recommendations. All drainage tightlines should be composed of appropriately sturdy material (such as rigid PVC), sized adequately according to anticipated flow, and anchored sufficiently. QG recommends slope tightlines be inspected by the owner periodically to look for signs of damage or displacement requiring repair. With permit approval, dispersion within the existing creek may be considered for reasonable quantities of stormwater, so long as appropriate energy reducing features are established at the outfall, such as fabric and quarry spalls, or other approved methods, to prevent erosion. QG recommends the site designer follow guidelines for dispersion set forth in the local stormwater 7 8112 Talbot Rd Consult Quality Geo, PLLC 12/21/2020 Project # QG20-082 design manual, or the WA Department of Ecology 2019 Stormwater Management Manual for Western Washington. Vegetation Improvements: Any trees showing the potential to fall within the building envelope or across the slope should be considered for removal, if possible. Where revegetation is not possible, stumps should be left in the ground to offer some stabilization of shallow surface soils. QG ultimately recommends the client consult a local arborist and the county code when determining which trees may be removed. Following construction and for long-term site use, maintaining existing downslope vegetation and installing additional beneficial deep rooting ground plantings within the vicinity of the improvements and over the slopes is encouraged assuming installation is done in a manner that minimizes slope face disturbance and erosional hazard in the long term. Adding vegetation will increase the erosional and hydrologic resistance of the slope and assist in retaining cover soils. Further information and recommendations for erosion control including typical beneficial native plantings for sloping areas are provided herein. Erosion Controls: Erosion is one of the most common driving forces leading to slope instability. In addition to the above commentary, the following general recommendations should be implemented in general to reduce long-term erosion potential of the slope below the project site and maintain slope stability: • Minimize the volume and velocity of water that travels toward and down the slope face (via proper choice of site development features including stormwater controls discussed above). • Avoid accelerating slope erosion and mass wasting due to human activity such as: ✓ Adding side -cast such as dumping landscape debris or fallen trees on or above the slopes. ✓ Using heavy construction equipment on or near steep slopes. ✓ Excavating near adjacent steep slopes toe or on slope face. ✓ Placing excavated soil near the steep slope crest. • Prior to construction, a silt fence and/or a continuous line of straw bales should be placed on the slopeward edge of the construction area. Heavy construction equipment, construction materials, or native and imported soils should not be placed behind the erosion control devices. Suitable temporary erosion and sediment control measures should be implemented at the construction site during and immediately after ground disturbance occurs. Temporary areas bare of vegetation should be protected from erosion via a blanket of straw or rolled erosion control product (RECP) during prolonged breaks in site work and prior to reseeding or revegetation. 8 8112 Talbot Rd Consult Quality Geo, PLLC 12/21/2020 Project # QG20-082 • At the end of the project, all bare surfaces and areas of disturbed vegetation should be replanted and maintained until fully reestablished. Concentrated surface water should not be allowed to traverse the slope during or after the construction phase of the project. Roof downspouts and footing drains should be routed into closed separate pipes which outfall into appropriate drainages. Outlets for these pipes should be protected from erosion through the use of rip -rap (quarry spalls) or some other energy dissipating device. Similarly, concentrated drainages should be captured in closed pipe systems and routed down slope to appropriate outfalls. • Clearing of existing vegetation outside the proposed building area on and adjacent to the existing slopes should be avoided except as approved by a qualified professional. This provides additional stability to the loose top soil and minimizes the effects of down -slope water movement. This is excepting removal of problem, dead, or dying, trees if posing a direct hazard to site installations or adjacent roadways. • Grading or excavation of soils during construction should be accompanied by grass reseeding and re -vegetation as the project is completed. According to "Vegetation Management: A Guide for Puget Sound Bluff Property Owners" (Manashe, 1993) the following types of vegetation provide good to excellent erosion control: Common Name Botanical Name Deciduous/Evergreen Mature Height t) Bi leaf Maple Acer macro h llum Deciduous 60 Douglas Fir Pseudotsu a menziesii Evergreen 200+ Evergreen Vaccinium ovatum Evergreen To 8 Oceanspray Holodiscus discolor Deciduous 10+ Oregon Grape Mahonia s . Evergreen To 6 Pacific Madrone Arbutus menziesii Evergreen 70 Red huckleberry Vaccinium parvifolium Deciduous To 12 Rose Rose spp. Deciduous 2-10 Salal Gaultheria shallon Evergreen To 4 Salmonberry Rubus s ectabilis Deciduous To 12 Serviceberry Amelanchier alnifolia Deciduous 12+ Snowberry Symphoricarpos albus Deciduous 3+ Vine Maple Acer cricinatum Deciduous 10+ Willow t Salix spp. Deciduous 10+ 9 8112 Talbot Rd Consult 12/21/2020 CLOSING. Quality Geo, PLLC Project # QG20-082 We trust this letter satisfies your project needs currently and thank you for the opportunity to be of service. QG wishes you the best while completing the project. Respectfully Submitted, Quality Geo, PLLC a, co 9110623 °,,Joe . 6 0 12/21/2020 LUKE PRESTON MCCAN14 Luke Preston McCann, L.G. Principal Geologist BPS D AVID Syi�cq� 46113 /0NM- Nick Taylor, P.E. Supervising P.E. Review Attachments: Limitations Appendix A. Site Region and Vicinity Maps Appendix B. Aerial Site Map Appendix C. Site Photos 10 12/21/2020 8112 Talbot Rd Consult 12/21/2020 LIMITATIONS Quality Geo, PLLC Project # QG20-082 Upon acceptance and use of this report, and its interpretations and recommendations, the owner shall agree to indemnify and hold harmless QG, including its owners, employees and subcontractors, from any adverse effects resulting from development and occupation of the subject site. Ultimately, it is the owner's choice to develop and live in such an area of possible geohazards (which exist in perpetuity across the earth in one form or another), and therefore the future consequences, both anticipated and unknown, are solely the responsibility of the owner. By using this report for development of the subject property, the owner must accept and understand that it is not possible to fully anticipate all inherent risks of development. The recommendations provided above are intended to reduce (but may not eliminate) such risks. This report does not represent a construction specification or plan and shall not be used or referenced as such. The information included in this report should be considered supplemental to the requirements contained in the project plans & specifications and should be read in conjunction with the above referenced information. The selected recommendations presented in this report are intended to inform only the specific corresponding subjects. All other requirements of the above - mentioned items remain valid, unless otherwise specified. Recommendations contained in this report are based on our understanding of the proposed development and construction activities, field observations and explorations, and laboratory test results. It is possible that soil and groundwater conditions could vary and differ between or beyond the points explored. If soil or groundwater conditions are encountered during construction that differ from those described herein, or If the scope of the proposed construction changes from that described in this report, QG should be notified immediately in order to review and provide supplemental recommendations. The findings of this study are limited by the level of scope applied. We have prepared this report in substantial accordance with the generally accepted geotechnical engineering practice as it exists in the subject region. No warranty, expressed or implied, is made. The recommendations provided in this report assume that an adequate program of tests and observations will be conducted by a WABO approved special inspection firm during the construction phase in order to evaluate compliance with our recommendations. This report may be used only by the Client and their design consultants and only for the purposes stated within a reasonable time from its issuance, but in no event later than 18 months from the date of the report. It is the Client's responsibility to ensure that the Designer, Contractor, Subcontractors, etc. are made aware of this report in its entirety. Note that if another firm assumes Geotechnical Engineer of Record responsibilities they need to review this report and either concur with the findings, conclusions, and recommendations or provide alternate findings, conclusions and recommendation. Land or facility use, on- and off -site conditions, regulations, or other factors may change over time, and additional work may be required. Based on the intended use of the report, QG may recommend that additional work be performed and that an updated report be issued. Non-compliance with any of these requirements by the Client or anyone else will release QG from any liability resulting from the use of this report. The Client, the design consultants, and any unauthorized party, agree to defend, indemnify, and hold harmless QG from any claim or liability associated with such unauthorized use or non-compliance. We recommend that QG be given the opportunity to review the final project plans and specifications to evaluate if our recommendations have been properly interpreted. We assume no responsibility for misinterpretation of our recommendations. 11 $112-Talbot Rd, "`� •' r} Edmonds, WA 98026$''! _ M Southw- Costco Whol 1 ' PFgR,IHVI-LLF� f•t"_p4 Fred'Mey... - ■-- — .5 2 �J Gooigle Mot R r 0 SrWA98:. t i �d � - �. •. t;"�� .gip A'� f1 Yl *46 46 ~ f -6 i a " �1■' i� Sup yr i ter �,g, Ar ICA 01 s _ Googfe 8112 Talbot Rd Consult 12/21/20 dgmw Appendix B. Aerial Site Map Talhnt IPA dip ? v `rf° Quality Geo, PLLC Project # QG20-082 0 0 60 SCALE (FEET) Site Map Source: King County UDAR & WA DNR Quality Geo, PLLC Scale & Locations are approximate Figure 2 8112 Talbot Rd Not for Construction 13 p a t ,R.". t 1[ MT6- !x• �, p LIALITY EO 12/21 /2020 Danielle Hill 8112 Talbot Rd Edmonds, WA Subject: 8112 Talbot Rd — Infiltration Addendum 8112 Talbot Rd, Edmonds, WA QG Project No.: QG20-082 & QG21-039 Dear Ms. Hill: At your request, Quality Geo NW, PLLC (QG) has completed a supplementary infiltration investigation for your project. QG understands that the city requests a geotechnical consultation to evaluate infiltration potential of site soils, and to provide any additional and necessary recommendation regarding stormwater considerations. The following addendum presents the findings and conclusions of our literature review, addresses feasibility of proposed site development, and provides additional geotechnical recommendations for stormwater design intended to reduce the inherent risks associated with site development within a potentially geologically hazardous area. SITE INVESTIGA TION METHODOL OGY Site exploration activities were performed on 4/21/2021. Exploration locations were marked in the field by an QG Project Geologist with respect to the provided map and cleared for public conductible utilities. Our exploration locations were selected by an QG Project Geologist prior to field work to provide safest access to relevant soil conditions. The geologist directed the advancement of 2 excavated test pits (TP). The test pits were advanced within the vicinity of the anticipated development footprint areas, to depths of 10.0 feet below present grade (BPG) in general accordance with the specified contract depth. During explorations QG logged each soil horizon we encountered, and field classified them in accordance with the Unified Soil Classification System (USCS). Representative soil samples were collected from each unit, identified according to boring location and depth, placed in plastic bags to protect against moisture loss, and were transported to the soil laboratory for supplemental Quality Geo NW, PLLC Geotechnical Investigations & Engineering Consultation Phone: 253-202-3675 1 Web: qualitygeonw.com I Mail: 420 Golf Club Rd SE, Ste 203, Lacey, WA 98503 8112 Talbot Rd Consult 5/16/2021 classification and other tests. SUBSURFACE CONDITIONS: Quality Geo NW, PLLC Project # QG20-082 & QG21-039 A general characterization of on -site soil units observed through local exposures on site within fallen tree pits. • Cover Soils — Silty Sand (SM): In both test pits, QG encountered an overriding layer of orange/brown silty sand. The soils were heavily mottled, suggesting the delayed percolation of stormwater. This unit extended from the surface to as deep at 3 feet across the site. • Outwash Sand — Sand (SP): The dominant underlying native soil across the upland and slope, appears to comprise a tan/gray sand, typically becoming cleaner with depth. These soils more closely resemble a recessional glacial outwash soil rather than a dense glacial till. The unit extended from 3 feet beyond 10 feet below present grade. Groundwater elevation is inferred to exist at or near the creek elevation. DISCUSSION RECOMMENDATIONS The findings of QG's site reconnaissance at the subject site do not indicate any excessively prohibitive conditions exist for the site, assuming appropriate site management efforts are maintained. Infiltration Rate Determination: During test pit excavations for general site investigation, QG additionally collected representative samples of native soil deposits among potential infiltration strata and depths. Soils across the site were identical. Representative soil samples were selected to characterize the sitewide infiltration conditions. We understand the project will be subject to infiltration design based on the Washington Department of Ecology Stormwater Management Manual for Western Washington (DoE SMMWW). For initial site infiltration characterization within the scope of this study, laboratory gradation analyses were completed including sieve and hydrometer tests for stormwater design characterization and rate determination to supplement field observations. Results of laboratory testing in terms of rate calculation are summarized below. 8112 Talbot Rd Consult Quality Geo NW, PLLC 5/16/2021 Project # QG20-082 & QG21-039 Laboratory results were interpreted to recommended design inputs in accordance with methods of the 2019 DoE SMMWW. Gradation results were applied to the Massmann (2003) equation (1) to calculate Ksat representing the initial saturated hydraulic conductivity. (1) log10(Ksat) = -1.57 + 1.90*D10 + 0.015*D60 - 0.013*D90 - 2.08*ff Corrected Ksat values presented below are a product of the initial Ksat and correction factor CFT. For a generalized site -wide design situation, we have applied a site variability factor of CFv = 1.0 along with typical values of CFt = 0.4 (for the Grain Size Method) and CFm = 0.9 (assuming standard influent control). (2) CFT=CFvxCFtx CFm = 1.0 x 0.4 x 0.9 = 0.36 Results were cross-referenced with test pit logs to determine the validity and suitability of unique materials as an infiltration receptor. Additional reduction factors were applied for logical rate determination. Table 1. Results Of Massmann Analysis TP Sample Unit Soil Fines Ksat Corrected LT Design Cation Exchange Organic # Depth Extent Type D10 D60 D90 o (/o) (in/hr) Ksat Infiltration Capacity Content BPG t (in/hr) Rate in/hr (meq/100g) % 1&2 5.0 3 to —1 .5 sand 0.194 1.678 28.75 3.2 34.27 11.25 2.5 2.8 0.8 Beneath sod and cover soils, the lower clean outwash sands were observed to generally exhibit minimal fines content and minimal oxidation patterns. Based on the proximity of the slope to the house, it is advised that the project engineer consider infiltration between the house and the street, rather than between the house and the slope. Based on the thick overriding layer of silty sand we do not recommend the designer pursue pervious pavements. The amount of overexcavation required to expose suitable infiltration soils is too excessive for such efforts at this time. For typical in -ground infiltration features infiltrating into the underlying clean sand (with their base below 3 feet in dept) we recommend a maximum design rate of up to 2.5 inch/hour be considered, which is typically suitable for most infiltration galleries, and considers potential reductions from compaction during construction. These rates are considered applicable to all areas of the subject site at the specified depths. QG recommends the facility designer review these results and stated assumptions per reference literature to ensure applicability with the proposed development, level of anticipated controls, and long- term maintenance plan. The designer may make reasonable adjustments to correction factors and the resulting design values based on these criteria to ensure design and operational intent is ki 8112 Talbot Rd Consult 5/16/2021 Quality Geo NW, PLLC Project # QG20-082 & QG21-039 met. We recommend that we be contacted if substantial changes to rate determination are considered. Treatment Potential: Depending on stormwater and runoff sources, some stormwater features such as rain gardens or pervious pavements may require treatment. Stormwater facilities utilizing native soils as treatment media typically require Cation Exchange Capacities (CEC) of greater than 5 milliequivalents per 100grams (meq/100g) and organic contents greater than 1% (this may vary depending on local code). Soils at likely infiltration depths did not meet these requirements. If treatment of stormwater is required, treatment media may need to be added, depending on the project engineer's final design. CLOSING. - We trust this letter satisfies your project needs currently and thank you for the opportunity to be of service. QG wishes you the best while completing the project. Respectfully Submitted, Quality Geo, PLLC )21 —Luke Preston MST F G_ I Licensed Engineering Geologist Attachments: Limitations Appendix A. Site Region and Vicinity Maps Appendix B. Aerial Site Map 4 8112 Talbot Rd Consult 5/16/2021 LIMITATIONS Quality Geo NW, PLLC Project # QG20-082 & QG21-039 Upon acceptance and use of this report, and its interpretations and recommendations, the owner shall agree to indemnify and hold harmless QG, including its owners, employees and subcontractors, from any adverse effects resulting from development and occupation of the subject site. Ultimately, it is the owner's choice to develop and live in such an area of possible geohazards (which exist in perpetuity across the earth in one form or another), and therefore the future consequences, both anticipated and unknown, are solely the responsibility of the owner. By using this report for development of the subject property, the owner must accept and understand that it is not possible to fully anticipate all inherent risks of development. The recommendations provided above are intended to reduce (but may not eliminate) such risks. This report does not represent a construction specification or plan and shall not be used or referenced as such. The information included in this report should be considered supplemental to the requirements contained in the project plans & specifications and should be read in conjunction with the above referenced information. The selected recommendations presented in this report are intended to inform only the specific corresponding subjects. All other requirements of the above - mentioned items remain valid, unless otherwise specified. Recommendations contained in this report are based on our understanding of the proposed development and construction activities, field observations and explorations, and laboratory test results. It is possible that soil and groundwater conditions could vary and differ between or beyond the points explored. If soil or groundwater conditions are encountered during construction that differ from those described herein, or If the scope of the proposed construction changes from that described in this report, QG should be notified immediately in order to review and provide supplemental recommendations. The findings of this study are limited by the level of scope applied. We have prepared this report in substantial accordance with the generally accepted geotechnical engineering practice as it exists in the subject region. No warranty, expressed or implied, is made. The recommendations provided in this report assume that an adequate program of tests and observations will be conducted by a WABO approved special inspection firm during the construction phase in order to evaluate compliance with our recommendations. This report may be used only by the Client and their design consultants and only for the purposes stated within a reasonable time from its issuance, but in no event later than 18 months from the date of the report. It is the Client's responsibility to ensure that the Designer, Contractor, Subcontractors, etc. are made aware of this report in its entirety. Note that if another firm assumes Geotechnical Engineer of Record responsibilities they need to review this report and either concur with the findings, conclusions, and recommendations or provide alternate findings, conclusions and recommendation. Land or facility use, on- and off -site conditions, regulations, or other factors may change over time, and additional work may be required. Based on the intended use of the report, QG may recommend that additional work be performed and that an updated report be issued. Non-compliance with any of these requirements by the Client or anyone else will release QG from any liability resulting from the use of this report. The Client, the design consultants, and any unauthorized party, agree to defend, indemnify, and hold harmless QG from any claim or liability associated with such unauthorized use or non-compliance. We recommend that QG be given the opportunity to review the final project plans and specifications to evaluate if our recommendations have been properly interpreted. We assume no responsibility for misinterpretation of our recommendations. 5 - � ATM: •'�,�• Edmonds, WA 9802 + A _ SDUihest +. • t a Op+Count ' Park Lostco:Wh I ILI PW +il � 4 } y .1' Google ..,rr}_• 1€!y r•. I�fi 4Y 1 } 8112' ,-Ihot. R Ed on l2`alhA98 2 h"• ,s , i 1 r Super r i �p• i _1 ��z7� nF .,ram'. V � 4. : �'�' •l" •,,�T �', . •�` _ _ - 9'. .� �"-: - n �,� ad'� =� ¢ .a f Google A.14!-:lp 8112 Talbot Rd Consult Quality Geo NW, PLLC 5/16/2021 Project # QG20-082 & QG21-039 Appendix B. Aerial Site Map Talbot Rd #w Site Map Source: King County L1DAR & WA DNR Quality Geo, PLLC g112 Talbot Rd Scale & Locations are approximate Not for Construction Quality Geo NW, PLLC Geotechnical Investigations & Engineering Consultation Phone: 253-202-3675 1 Web: qualitygeonw.com I Mail: 420 Golf Club Rd SE, Ste 203, Lacey, I& 0 60 SCALE (FEET) Figure 2 WA 98503 8112 Talbot Rd Consult Quality Geo NW, PLLC 5/16/2021 Project # QG20-082 & QG21-039 Appendix C. Laboratory Testing Results Materials Testing & Consulting, Inc. Geotenhlvcal E.ngneeiing • Special Inspection - Metenels Testing - Enviranrnenlal Consulting Sieve Report P-J-11- Q-C'.. Quatily Gar, PLLC UWM R-i-d::.2.hprv21 LI, i---h Ilm-m-li- S-1- Pruj-1 N- 21SO 9 tiamplyd Br_ CL;emd rir Lgaded Sand w Lh (.aawdO Jie•l-- Q. •*y Cm, PLLC V.I. I-lyd: ''R-Apr'-1 LIIA�MD.7A87 rulerHd�TI?-] ia� 3 ft'I estud H% :. L�i:rr_ ACCRE04TE4 tian nY- B214548 �«•••• ��•••�. "•••• "•.• ANI M QdY 14,.45'I'.FS B-2419, AhTM 1343I.I. ASTH 10.511E1 I5. J I-': �.. %C--1 - 2S5".o C-I . of 0-1unr,{'� - I)S3 Sp-bl-bl- Riv. a.I aJ .. °%^ - 683°e C--1E aruuir ky.C:L - IA4 N. spas QiiA L250 n"n %Sill.& C4ay-3.2% 1-U.&J.L-3-89 Sr.q1r M-h *-I NIA Gib- 6A 18- Liquid Limit- We Pi fic Limil - uh Day- 1.240 n PL.L kyln&- ua Mvxlurx 56,- npled - 5-;% and F. D'- U'm Illll] Sgw-Y m1 - a P&4d SaodEqui Lmi - 6-,_- 3xs.'tu Imn Fm -1L L F-- ry Req'd Fmrrua14 I F-- Im, 0.mi3 : `v FTa ml ". I. Farr, - n. d Frac1- kr ,1, F.. - ASTAI A.M. AST 81 D490, ASTM C40 .ter A A -pal ,d i Irur0.rl, r ksrreAl k',mn i F-6d, r rmrL hat e,rrm • mraia 91en I. SLx lPeirir tiprt, 41.Y spry MI• L100` 30000 JtMr. I[ ir. 0.0% IQuil- 15UA0 1011% L"-[r% 0.0% I �J '•.lxl0 IOU% L00.0'd 0.0% '� � nUlr 111111 i0M 1001. L00.0% 0.0% 4 Vlr LDom Iw% LOX-O% 0.0% tl11, 71J00 100% L00.M 0.0% ' 4- 63J00 100 , L00..O% -0.0% ' ulr AN IN% 1W% L00.0% 0.0% oa 175- 000 98% L00.0% 0.0% 1111 37-4 94% L00.0% -0.0% I _i 3LS0 911. L(a fr% 0.0% 06 LA , 23A0 S2% 89'. L00.0% 0.0% 1A: 19A0 94% JJa•. L00..O% 0.0% � .n 3.B L6A0 ziY•. L00.0'd 0.0% L2• 12 4 93% K3•. L00.4C: 0.0% 3.t. 9-% 70% 79•. L00.04i 0.0% n L.+4• G-30 '7J•, L9P.4}S 0.0% tl4 4-7S 71% 71•. L00.0% 0.0% tlS 23d n.•. L00.0% 0.0% n tll0 200 67% 6". L9P.UA 0.0% JA tl7JT 0.7L{I dl•. L00.1r% 0.0% tl30 0.600 3S•. L00-Q% 0.0% a40 0.4°5 31% 31•. L00.0% 0.0% •s ,m d5o 0.300 �•. 0 Loo (r% 0.0% tl60 0.250 15% L00.-04L 0.0% tl80 0, 9% L00-U'd .0.0% tl100 0.150 RSL 6!G LM(r% 0.0% tl140 0.LOn d!i LM.0% tl170 0.090 d94 L00.0% .00% tl2170 Gd:S ._ 3.2'.5 LdO.-04a 0.41k - :. �- --•� i'umnent J. kl�.0 Blo,�g0�,rtiL-, Quality Geo NW, PLLC Geotechnical Investigations & Engineering Consultation Phone: 253-202-3675 1 Web: qualitygeonw.com I Mail: 420 Golf Club Rd SE, Ste 203, Lacey, WA 98503 8112 Talbot Rd Consult 5/16/2021 PNtiAoo�tl aaa, FERIALS TESTING CHRYSL€R DR urlington , WA 99233 �boratory #: 521-07463 Cation Exchange CEC rneq/100g Other Tests: Organic Matter (L01 360} Quality Geo NW, PLLC Project # QG20-082 & QG21-039 '� MIIW 11��. sot test farm consultants, inc. ON[r. iianlMiE@Y IM iYilihSai: ,d{rtihiid9? +w.any Date Received: 4/27/2021 Grower 21SO19 QC Field: 821-0540 HILLTP-1 AT . _ Sampled By: Customer Account 4: Sall Test Results Customer Sample ID: 2.8 PH 1:1 E.C.1:1 m.mhos/cm Est Sat Paste E.C. rn,mhos/cm Effervescence S %. Ammonium - N mg/kg Organic Matter W.B. % 9 Lbs 71 iy, ENR: USDA United States Department of Agriculture N RCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Snohomish County Area, Washington February 11, 2021 3 Custom Soil Resource Report 3 Soil Map 0 0 NV NV N N 549M 549100 549110 549120 549130 549140 549150 549160 549170 549180 47o 50' 3Z' N -5 — 47o 50' 32" N ■� ti 40 . •i - jyJf1` S 'k .Ww µ fry Ak - ••± p J� ''r tiw ow = li • hi -scal =-. 47' 50' 28" N 47° 50' 28" N 549090 549100 549110 549120 549130 549140 549150 549160 549170 549180 3 3 a Map Scale: 1:637 if printed on A portrait (8.5" x 11") sheet. a Meters N N 0 5 10 20 30 Feet 0 30 60 120 180 Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 1ON WGS84 MAP LEGEND Area of Interest (AOI) 0 Area of Interest (AOI) Soils 0 Soil Map Unit Polygons .y Soil Map Unit Lines Soil Map Unit Points Special Point Features U Blowout ® Borrow Pit Clay Spot a Closed Depression * Gravel Pit Gravelly Spot 0 Landfill A. Lava Flow 41& Marsh or swamp Mine or Quarry OMiscellaneous Water 0 Perennial Water V Rock Outcrop + Saline Spot Sandy Spot 4W Severely Eroded Spot Sinkhole 3) Slide or Slip o Sodic Spot Custom Soil Resource Report Spoil Area Stony Spot 40 Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1:24,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Snohomish County Area, Washington Survey Area Data: Version 22, Jun 4, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Sep 2, 2018—Sep 25, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 5 Alderwood-Urban land complex, 2 to 8 percent slopes 0.9 100.0% 0.9 100.0% Totals for Area of Interest Custom Soil Resource Report Snohomish County Area, Washington 5—Alderwood-Urban land complex, 2 to 8 percent slopes Map Unit Setting National map unit symbol: 2hz9 Elevation: 50 to 800 feet Mean annual precipitation: 25 to 60 inches Mean annual air temperature: 48 to 52 degrees F Frost -free period: 180 to 220 days Farmland classification: Not prime farmland Map Unit Composition Alderwood and similar soils: 60 percent Urban land: 25 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Alderwood Setting Landform: Till plains Parent material: Basal till Typical profile H1 - 0 to 7 inches: gravelly ashy sandy loam H2 - 7 to 35 inches: very gravelly ashy sandy loam H3 - 35 to 60 inches: gravelly sandy loam Properties and qualities Slope: 2 to 8 percent Depth to restrictive feature: 20 to 40 inches to densic material Drainage class: Moderately well drained Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately low (0.00 to 0.06 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: None Frequency of ponding: None Available water capacity. Low (about 3.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4s Hydrologic Soil Group: B Forage suitability group: Limited Depth Soils (G002XN302WA) Other vegetative classification: Limited Depth Soils (G002XN302WA) Hydric soil rating: No Minor Components Terric medisaprists, undrained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes Custom Soil Resource Report Norma, undrained Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes Mckenna Percent of map unit: 5 percent Landform: Depressions Other vegetative classification: Wet Soils (G002XN102WA) Hydric soil rating: Yes Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section VI, Page 1 Section VI — Other Permits Section VI Summary: Narrative The site will not require permits beyond those from the City of Edmonds. C 4M ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section VII, Page 1 Section VII — Bond Quantities, Declaration of Covenant, & Operation and Maintenance Manual Section VII Summ Narrative The Bond Quantity Worksheet is a standalone document that can also be submitted to the City of Edmonds separately from this document. A Declaration of Covenant is provided for the onsite BMPs proposed. The Operation and Maintenance Manual is a standalone document that will be given to the owner(s) following the construction of the project. n1arrntivo The maintenance covenant contained herein is for the Hill Residence improvements project. The contractor will be responsible for the maintenance and operation of all stormwater structures and BMPs requiring maintenance during construction and, after construction, responsibility will pass to the home owner(s). The project contractor will be responsible for passing along the information in this maintenance manual to the owner(s). Upon request by the City, it shall be made available for their inspection. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com After recording return to: City Clerk City of Edmonds 121 Fifth Avenue North Edmonds, WA 98020 Document Title(s) Declaration of Covenant - Private Stormwater Facility Reference Number(s) of Related Documents N/A Grantor(s) (Last, First and Middle Initial) Hill, Danielle Grantee(s) (Last, First and Middle Initial) City of Edmonds Legal Description (abbreviated form; i.e., lot, plat or section,. township, range, quarter/quarter) NE 1/4, SE 1/4, SECTION 7, TOWNSHIP 27 NORTH, RANGE 4 EAST, W.M. Assessor's Property Tax Parcel/Account Number at the Time of Recording: 0059-440000-8701 The Auditor/Recorder will rely on the information provided on this form. The staff will not read the document to verify the accuracy or completeness of the indexing information provided herein. DECLARATION OF COVENANT Private Stormwater Facility WHEREAS, the undersigned Declarant(s) have installed a stormwater facility under Edmonds Community Development Code Chapter 18.30 known as a "low impact development best management practices (LID BMP)" in lieu of other required more conventional stormwater systems, as selected below: ❑ Drywell ElPermeable Pavement ❑ Gravelless Chamber ❑ Rain Garden / Bioretention Cell ❑ Other A Infiltration Trench WHEREAS, the City of Edmonds has allowed installation of the LID BMP, subject to the execution and recording of this Declaration of Covenant; NOW, THEREFORE, THE UNDERSIGNED DECLARANT(S), being the owners of the real property ("the Property") located at the following address: 8112 Talbot Rd in the City of Edmonds, Washington, and legally described on Exhibit A attached hereto and incorporated herein by this reference as if set forth in full, hereby covenants and agrees, on behalf of himself/herself/themselves/itself and his/her/their/its successors and assigns, as follows: Declarant(s) warrant that he/she/they are the owners of the property described on Exhibit A and have the authority to impose this covenant on the property and bind all future owners, successors, and assigns of the Declarant(s). The Declarant(s), future owners, successors, and assigns of the Declarant(s) shall be referred to collectively as "Owners." 2. The Owners of the property described on Exhibit A agree that the property contains a stormwater management facility called a "LID BMP," which was installed to mitigate the stormwater quantity and quality impacts of some or all of the impervious or non-native pervious surfaces on the property. "Low impact development" means development conducted in a way that seeks to minimize or completely prevent alterations to the natural hydrology of the site. Low impact development includes site planning and design to reduce alterations of natural soil and vegetation cover, minimize impervious surfaces, and specific practices that help to replicate natural hydrology such as permeable pavements, green roofs, soil amendments, bioretention systems, and dispersion of runoff. 3. The Owners of the property described on Exhibit A shall maintain the size, placement, and design of the LID BMP as depicted on the approved site plan, Exhibit B, and design details shall be maintained and may not be changed without written approval either from the Engineering Division of the City of Edmonds or through a future development permit from the City of Edmonds. Chemical fertilizers and pesticides shall not be used where LID BMP is located. . All costs of maintenance and repair shall be the sole responsibility of the Owners. 4. The Owners of the property described on Exhibit A shall inspect LID BMPs annually for physical defects. After major storm events, the system shall also be checked to ensure that the overflow system is working properly. The Owners also shall maintain all LID BMP so it functions as designed on a year-round basis. 5. The City of Edmonds is hereby granted by the Owners the right, but not the obligation, to enter upon the property described on Exhibit A at all reasonable times for the purpose of inspecting the private stormwater LID BMP facility. If, as the result of any such inspection the City of Edmonds determines that the LID BMP is in disrepair, requires maintenance or repair, or is otherwise not functioning as provided in the BMP site plan, the City Engineer or his designee shall have the right, but not the obligation, to order the Owners of the property described on Exhibit A to maintain or repair the same. 6. If the City of Edmonds determines that the LID BMP requires maintenance or repair pursuant to Section 5, the City of Edmonds shall provide notice to the Owners of the deadline within which such maintenance or repair must be completed. Said notice may further advise that, should the violator fail to perform required maintenance or make repairs within the established deadline, the work may be done by the city or a contractor designated by the City Engineer and the expense thereof shall be charged to the Owners. The City's officers, agents, employees, and contractors shall have the right, which is hereby granted by the Owners, to enter upon the property described on Exhibit A in order to perform such work. The Owners shall bear the cost of all work performed. 7. The Owners shall indemnify, defend and hold harmless the City of Edmonds, its officers, officials, employees and agents from any and all claims, demands, suits, penalties, losses, damages, judgments, attorneys' fees and/or costs of any kind whatsoever, arising out of or in any way resulting from the approval of the LID BMP, the installation and presence of the LID BMP, and the acts or omissions of the Owners, their officers, employees, contractors, and agents relating to the construction, operation and maintenance of the LID BMPs on the property, except for the City's intentional and willful tortious acts, and waive and release the City of Edmonds from any and all claims for damages and injunctive relief which the Owners may themselves have now or in the future, by reason of the construction, maintenance and operation of said LID BMPs. 8. This covenant shall run with the land and be binding upon the Declarant(s), as the owner of the property described on Exhibit A, and on Declarant's successors and assigns as to such property. Dated: DECLARANT(S): (Signature) (Print Name) (Signature) (Print Name) State of Washington M1 County of Snohomish APPROVED: CITY OF EDMONDS (Signature) (Print Name) (Title) On this day personally appeared before me { Declarant(s) } to me known to be the individual, or individuals described in and who executed the within and foregoing instrument, and acknowledged that he/she/they signed the same as his/her/their free and voluntary act and deed, for the uses and purposes therein mentioned. SUBSCRIBED AND SWORN before me this day of , 201_. (Signature) (Name legibly printed or stamped) Notary Public in and for the State of Washington. Residing at: My commission expires Exhibit A LOT 87, PLAT OF TALBOT PARK AS RECORDED IN VOLUME 12 OF PLATS AT PAGE 107, RECORDS OF SNOHOMISH COUNTY, WASHINGTON; EXCEPT THAT PORTION OF LOT 87 DESCRIBED AS FOLLOWS: COMMENCING AT THE NORTHWEST CORNER OF SAID LOT 87; THENCE SOUTH 180 02' 30" WEST A DISTANCE OF 158.40 FEET; THENCE NORTH 710 57' 30" WEST A DISTANCE OF 18.05 FEET TO A POINT ON THE WESTERLY LINE OF SAID LOT 87; THENCE NORTH 240 32' 34" EAST ALONG SAID WESTERLY LINE A DISTANCE OF 159.43 FEET TO THE POINT OF BEGINNING; SITUATE IN THE COUNTY OF SNOHOMISH, STATE OF WASHINGTON. Exhibit B N 86'20'00" E 120.00' TALBOT ROAD ; -- �� -.. -�----__--=----ss----u----=_----__----__- --a----u- --u� 86'20 00 E _ _ N' ----- _�- 8" 10 10 DEC l ` DEC }/ 27' X 10'�X 3' \ INFILTR4TION TRENCH f \I li I _J aR a i r 10"X2 CO,VEED IJ� P C, PI� 1 I HOUSE #8112 F.F.=80.83' II �� E'' I i P r r r \ / � d" > fs� LOT AREA 32,820 SF nn.5944nnnOR7C ----------------- Jreo J IJ ,I II " I I zl 3 �JI I I � I I " I I i CONVEYANCE PIPE, TYP / / / i i CATCH/BASIN, TYP i YARD DRAIN, TYP Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section VII, Page 2 Hill Residence 8112 Talbot Rd Edmonds, WA 98026 OPERATION AND MAINTENANCE MANUAL Date: May 2021 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section VI I, Page 3 Operation and Maintenance Manual This Operation and Maintenance Manual has been created for the Hill Residence, a site and stormwater utility improvement project on a 0.77-acre lot. The proposed storm system consists of an infiltration trench which will collect runoff from the existing roof as well as all new and replaced impervious areas on -site. Included in the Operation and Maintenance Manual is an 11" x 17" Grading and Drainage plan sheet showing the location of the infiltration system. Please note that this map is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as -built drawings are completed for the site. The contractor will be responsible for the maintenance and operation of all stormwater structures and BMPs requiring maintenance during construction and, after construction, responsibility will pass to the homeowner(s). A map of the project area can be seen on the following page in Figure VII-1. Included in this manual are maintenance sheets taken from the 2014 Stormwater Management Manual for Western Washington for the following facilities/activities: Catch Basins: Concrete structures with steel grates that collect stormwater runoff from the site and act as junctions for storm conveyance pipes. See "No. 5" for maintenance. Infiltration Trench: A drainage facility designed to use the hydrologic process of surface and stormwater runoff soaking into the ground, commonly referred to as a percolation, to dispose of surface and stormwater runoff. Vegetation Management: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Facilities shall be inspected for defects listed in the following facility sheets. Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. The facility sheets list the potential conditions warranting maintenance and the expected result following any maintenance. Several engineer's notes for specific tasks are provided within the facility sheets. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an "as needed" basis: (a) when the described defect is visible to whomever performs the yearly inspection, or (b) should any defect become apparent between inspections. CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com NE 1 /4, SE 1 /4, SECTION 7, C8 RIM=81.09 27' x 10' z 3' GRAVEL IE 12" CPP(W)=76.39 FOUND CASED CONE. MON W/ 2-112" BRASS DISK & PUNCH. INFILTRATION TRENCH IE 12" CPP(SE)=76.39 DOWN 1.2'. VISITED 12-21-20 CB RIM=76.98 CB RIM=78.01 TOP:76.00 4 \ \I APPROXIMATE LOCATION OF CITY IS 12 CPP(W)=74.91 \ IE IV IN): 75.00 C3. OF LVNNWOOD SEWER FORCE IF 12" CPP(E)-74.91 \ IEOU OU MAIN PER EDMONDS GIS MAP IE 12 CPP E =/4.79 IE 8" RCP(N)=I5. 10 BOT: 73.00 : 3. a BFeRB+D) ----- ----- - G4 _ /� I--N ---- I BS'49'35'E ---- ,00' E 120.00' RIM=71.70 m �' 8@ TALBOT ROAD 55'' RYC(W_51.65 8" PVO(E3=5,.95 I S 1 21 - LF^' 6" PVC @ - -MIN _ c � � INSTAL -ss--- OBSERVATION WELL APPROXIMATE LOCATION OF SIDE _ SEWER PER SIDE SEWER CARD I 1 CONCRETE WALKWAY 1 e ROOF AND / A,I FOOTING DRAIN ,� 1 12" AREA DRAIN / 12 1 RIM: 80.25 RIM: 78.80 I IE (6" E): 78.25 3 7 IE (6" N): 76.80 1 GRAVEL PAVEMENT HOUSE 1 SECTION, TYP .,1 FRONT !8112 T ENTRY F.F./ =6.C-' 111 12" AREA DRAIN 7� I, 80.83 1 RIM: 80.50 11 _ -.1 80.90 - IE(6'E):78.00 1 1 COYEREO L 1 12" AREA DRAIN = PORCH 1 RIM: 80.29 1 IE IS" E): 78.29 1 005944000OBB02 1 1 I � I I / a 1 / 80.49 / 45 LF - 6" PVC 80.75 / @0.5%MIN / I 8099Y/`0# -V�. CONCRETE OR COURT •� 1' 7\\D1 \` n LOT AREA / 14x2 C \ y \ ��. `\\\\ \ BFR Nq�� 32,820 SF \ \ \ \ \ 00594400008701 \ \ 12" \\14W \\ \�7 / \ I \ \ \ \ \ \ \\\\ 1999 \\ \ / V APPROXIMATE LOCATION OF EXISTING 80 ^7 WATERSERVICE LINE \ 62 LP' 6" PVC @0.5%MIN )/ TOWNSHIP 27 NORTH, RANGE 4 EAST, W.M. GRADING AND DRAINAGE PLAN NOTES: 1. SOILS REPORTS REPORT NUMBER: QG21-039 (INFILTRATION ADDENDUM) PREPARED BY: QUALITY PLLC �sQ 02 202 DATED: DECEMBER 21, 0 �- 2. ALL DISTURBED AREAS ON AND OFF -SITE SHALL BE COMPOST -AMENDED PER THE REQUIREMENTS OF BMP T5.13 ss' IN THE STORMWATER MANUAL VOLUME V, CHAPTER S. SS' 3. VEGETATION AFFECTED BY 8" PIPE FROM DETENTION SYSTEM SHALL BE RESTORED TO ORIGINAL CONDITION TO \ THE AXIMUM EXTENTS PRACTICABLE. 4. AM I NIMUM OF T HORIZONTAL SEPARATION AND V VERTICAL SEPARATION IS REQUIRED BETWEEN DRY S UTILITIES (POWER, GAS, PHONE, CABLE, ETC)ANDSEWER, WATER AND STORM, AND A MINIMUM OF5' PHALT HORIZONTAL SEPARATION AND V VERTICAL SEPARATION FROM ANY CITY OWNED LINES. BERM ALONG 5. A MINIMUM OF T OF COVER IS REQUIRED FOR ALL PIPES LOCATED UNDER DRIVEABLE SURFACES AND V OF DRIVEWAY EDGE COVER UNDER LANDSCAPE SURFACES. �CB RIM-81.28 � IE 12" CPP(N)=76.28 80.60 TYPE ICB \ /// /i •1 - 79 92 / RIM: 80.40 \ IE (6" S): 77.90 1 2 3 80.15 79.92 80.55 ` 'G TYPE 1 CB RIM: 79.74 < .�O 2 IE (6"SWI: 75.99 IE (6" NEI:75.99 1 2 3 4 ° IE(6"NW): 75.89 80.17 CONCRETE PAVER a\ <' 4' DRIVEWAY W/GRAVEL 803,] BASE COURSE PER ARCH 80,17 / h'. / 28 LF^6"PVC @0.5%MIN 8030 F[,.\ TYPE ICB / RIM: 7990 00594400008602 1'a 80.03 ,/ IE(6 W): 76.50 I'DA, °! 1- �~ IE(6 S) 76.50 1 2 3 ' 80.30 / IE (6 NQ:76.40 C3. C3. C3. 7, Q/' 1 F, 45 LF ^'6"PVC@0.5%MIN 1a 12 AREA DRAIN ry RIM: 8058 IE(15'ft 77.39 80.62 IE (6' N): 77.29 / CONCRETE CURB TO / / 80.62 MATCH EXISTING GRADE / / AT PROPERTY LINE / 80.86 / / / / / / / / / / / / / / / / / 00594400008601 / / / / i GF;ADING QUANTITIES PAVING LEGEND TOTAL EXCAVATION (CUT) 310 CUYDS TOTAL GRAVEL EMBANKMENT (FILL) 120 CUYDS - TOTAL 430 CU YDS CONCRETE PAVERS THE QUANTI FIES SHOWN ABOVE ARE FOR THE PERMIT PROCESS NEW CONCRETE ONLY. THESE VALUES ARE APPROXIMATE. DO NOT USE FOR BIDDING, PAYMENT, OR ESTIMATING PURPOSES. IMPERVIOUS SURFACES SURFACE SURFACE AREA (SF) STORMWATER CONTROL MEASURE EXISTING ROOF TO REMAIN 3,896 RUNOFFROUTED THROUGH ROOF DRAINS TO INFILTRATION TRENCH. NEW/ CONCRETE PAVER 4,119 RUNOFF COLLECTED IN CATCH BASINS, ROUTED TO DRIVEWAY INFILTRATION TRENCH. NEW/REPLACED CONCRETE 1,356 RUNOFF COLLECTED IN AREA DRAINS/CATCH BASINS, SURFACE CONNECTED TO INFILTRATION TRENCH. NEW GRAVEL SURFACE 2619 RUNOFF COLLECTED IN AREA DRAINS/CATCH BASINS, CONNECTED TO INFILTRATION TRENCH. NOTE: TOTAL NEW/REPLACED IMPERVIOUS SURFACES ARE 8,094 SF, ADDITIONAL 3,896 SF ADDED TO INFILTRATION TRENCH FROM EXISTING ROOF. 4" DIA PERFORATED PVC PIPE WITH 6" OF 1" MINUS GRAVEL 8"MIN FROM WOOD. ALL AROUND, WRAPPED IN SEE STRUCTURAL DRAWINGS NON -WOVEN GEOTEXTILE FABRIC, SLOPE AT 0.5% MIN. TURN DOWN PERFORATIONS AS SHOWN 6" DOWNSPOUT TIGHTLINE TO FINISHED GRADE - I- CONVEYANCE SYSTEM @ 0.5% MIN.PLACENEXTTOFOOTING DRAIN OR AS SHOWN ON III GRADING & DRAINAGE PLAN -111- (CONTRACTOR MAY LOCATE ON EITHER SIDE OF FOOTING DRAIN) 00 o O O _ OO 00 O Ov0° a 0' ,O LINE OF MAX EXCAVATION. �00 - 0 .'4 < IF SOIL IS OVEREXCAVATED, 0 0 °O O a REPLACE WITH LEAN MIX 0OOo - CONCRETE / FOOTING 1 SCALE: 1"=20 GRADING AND DRAINAGE PLAN © FOOTING AND ROOF DRAIN SECTION ' ALE NTS 20 0 10 20 40 APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION C G ENGINEERING 250 4TH AVE. S., SUITE 200 EDMONDS, WASHINGTON 98MO PHONE (425) 778-8500 FAX (425) 778_5536 06/02/21 w O DESIGN: BJL DRAWN: ATD CHECK: JPU JOB NO: 20439.20 DATE: 03/01/2021 /W V Q Z Q N � J 0 N Do F- Ld W 0) o m W Q Np Z Z Q ~ (' Z Z o � J I m OD W 0 0- L9 SHEET C3.1 No. 1 — Detention Ponds Maintenance Defect Conditions When Maintenance Is Results Expected When Component Needed Maintenance Is Performed Beaver Dams Dam results in change or function of Facility is returned to design function. the facility. (Coordinate trapping of beavers and removal of dams with appropriate permitting agencies) Insects When insects such as wasps and Insects destroyed or removed from site. hornets interfere with maintenance Apply insecticides in compliance with activities. adopted IPM policies Tree Growth Tree growth does not allow Trees do not hinder maintenance and Hazard maintenance access or interferes activities. Harvested trees should be Trees with maintenance activity (i.e., slope recycled into mulch or other beneficial mowing, silt removal, vactoring, or uses (e.g., alders for firewood). equipment movements). If trees are Remove hazard Trees not interfering with access or maintenance, do not remove If dead, diseased, or dying trees are identified (Use a certified Arborist to determine health of tree or removal requirements) Side Slopes Erosion Eroded damage over 2 inches deep Slopes should be stabilized using of Pond where cause of damage is still appropriate erosion control measure(s); present or where there is potential for e.g., rock reinforcement, planting of continued erosion. grass, compaction. Any erosion observed on a If erosion is occurring on compacted compacted berm embankment. berms a licensed civil engineer should be consulted to resolve source of erosion. Storage Area Sediment Accumulated sediment that exceeds Sediment cleaned out to designed pond 10% of the designed pond depth shape and depth; pond reseeded if unless otherwise specified or affects necessary to control erosion. inletting or outletting condition of the facility. Liner (If Liner is visible and has more than Liner repaired or replaced. Liner is fully Applicable) three 1/4-inch holes in it. covered. Pond Berms Settlements Any part of berm which has settled 4 Dike is built back to the design (Dikes) inches lower than the design elevation. elevation. If settlement is apparent, measure berm to determine amount of settlement. Settling can be an indication of more severe problems with the berm or outlet works. A licensed civil engineer should be consulted to determine the source of the settlement. Piping Discernable water flow through pond Piping eliminated. Erosion potential berm. Ongoing erosion with potential resolved. for erosion to continue. (Recommend a Goethechnical engineer be called in to inspect and evaluate condition and recommend repair of condition. Volume V — Runoff Treatment BMPs — Deeember 2014 4-33 No. 1 — Detention Ponds Maintenance Defect Conditions When Maintenance Is Results Expected When Component Needed Maintenance Is Performed Emergency Tree Growth Tree growth on emergency spillways Trees should be removed. If root Overflow/ creates blockage problems and may system is small (base less than 4 Spillway and cause failure of the berm due to inches) the root system may be left in Berms over 4 uncontrolled overtopping. place. Otherwise the roots should be feet in height. Tree growth on berms over 4 feet in removed and the berm restored. A height may lead to piping through the licensed civil engineer should be consulted for proper berm/spillway berm which could lead to failure of restoration. the berm. Piping Discernable water flow through pond Piping eliminated. Erosion potential berm. Ongoing erosion with potential resolved. for erosion to continue. (Recommend a Goethechnical engineer be called in to inspect and evaluate condition and recommend repair of condition. Emergency Emergency Only one layer of rock exists above Rocks and pad depth are restored to Overflow/ Overflow/ native soil in area five square feet or design standards. Spillway Spillway larger, or any exposure of native soil at the top of out flow path of spillway. (Rip -rap on inside slopes need not be replaced.) Erosion See "Side Slopes of Pond" Volume V — Runoff Treatment BMPs — Deeember 2014 4-34 No. 2 — Infiltration Maintenance Defect Conditions When Maintenance Is Results Expected When Component Needed Maintenance Is Performed General Trash & Debris See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1). Poisonous/Noxious See "Detention Ponds" (No. 1). See "Detention Ponds" Vegetation (No. 1). Contaminants and See "Detention Ponds" (No. 1). See "Detention Ponds" Pollution (No. 1). Rodent Holes See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1) Storage Area Sediment Water ponding in infiltration pond after Sediment is removed rainfall ceases and appropriate time and/or facility is cleaned allowed for infiltration. Treatment basins so that infiltration system should infiltrate Water Quality Design Storm works according to Volume within 48 hours, and empty within design. 24 hours after cessation of most rain events. (A percolation test pit or test of facility indicates facility is only working at 90% of its designed capabilities. Test every 2 to 5 years. If two inches or more sediment is present, remove). Filter Bags (if Filled with Sediment and debris fill bag more than 1/2 Filter bag is replaced or applicable) Sediment and full. system is redesigned. Debris Rock Filters Sediment and By visual inspection, little or no water flows Gravel in rock filter is Debris through filter during heavy rain storms. replaced. Side Slopes of Erosion See "Detention Ponds" (No. 1). See "Detention Ponds" Pond (No. 1). Emergency Tree Growth See "Detention Ponds" (No. 1). See "Detention Ponds" Overflow Spillway (No. 1). and Berms over 4 feet in height. Piping See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1). Emergency Rock Missing See "Detention Ponds" (No. 1). See "Detention Ponds" Overflow Spillway (No. 1). Erosion See "Detention Ponds" (No. 1). See "Detention Ponds" (No. 1). Pre -settling Facility or sump 6" or designed sediment trap depth of Sediment is removed. Ponds and Vaults filled with Sediment sediment. and/or debris Volume V — Runoff Treatment BMPs — Deeember 2014 4-35 No. 5 — Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash & Trash or debris which is located immediately No Trash or debris located Debris in front of the catch basin opening or is immediately in front of blocking inletting capacity of the basin by catch basin or on grate more than 10%. opening. Trash or debris (in the basin) that exceeds 60 No trash or debris in the percent of the sump depth as measured from catch basin. the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of six inches clearance from the debris surface to the invert of the lowest pipe. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free blocking more than 1 /3 of its height. of trash or debris. Dead animals or vegetation that could No dead animals or generate odors that could cause complaints vegetation present within or dangerous gases (e.g., methane). the catch basin. Sediment Sediment (in the basin) that exceeds 60 No sediment in the catch percent of the sump depth as measured from basin the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe. Structure Top slab has holes larger than 2 square Top slab is free of holes Damage to inches or cracks wider than 1/4 inch and cracks. Frame and/or Top Slab (Intent is to make sure no material is running into basin). Frame not sitting flush on top slab, i.e., Frame is sitting flush on separation of more than 3/4 inch of the frame the riser rings or top slab from the top slab. Frame not securely and firmly attached. attached Fractures or Maintenance person judges that structure is Basin replaced or repaired Cracks in unsound. to design standards. Basin Walls/ Bottom Grout fillet has separated or cracked wider Pipe is regrouted and than 1/2 inch and longer than 1 foot at the secure at basin wall. joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. Settlement/ If failure of basin has created a safety, Basin replaced or repaired Misalignment function, or design problem. to design standards. Vegetation Vegetation growing across and blocking more No vegetation blocking than 10% of the basin opening. opening to basin. Vegetation growing in inlet/outlet pipe joints No vegetation or root that is more than six inches tall and less than growth present. six inches apart. Contamination See "Detention Ponds" (No. 1). No pollution present. and Pollution Volume V — Runoff Treatment BMPs — December 2014 4-38 No. 5 — Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed Catch Basin Cover Not in Cover is missing or only partially in place. Catch basin cover is Cover Place Any open catch basin requires maintenance. closed Locking Mechanism cannot be opened by one Mechanism opens with Mechanism maintenance person with proper tools. Bolts proper tools. Not Working into frame have less than 1/2 inch of thread. Cover Difficult One maintenance person cannot remove lid Cover can be removed by to Remove after applying normal lifting pressure. one maintenance person. (Intent is keep cover from sealing off access to maintenance.) Ladder Ladder Rungs Ladder is unsafe due to missing rungs, not Ladder meets design Unsafe securely attached to basin wall, standards and allows misalignment, rust, cracks, or sharp edges. maintenance person safe access. Metal Grates Grate opening Grate with opening wider than 7/8 inch. Grate opening meets (If Applicable) Unsafe design standards. Trash and Trash and debris that is blocking more than Grate free of trash and Debris 20% of grate surface inletting capacity. debris. Damaged or Grate missing or broken member(s) of the Grate is in place and Missing. I grate. meets design standards. No. 6 — Debris Barriers (e.g., Trash Racks) Maintenance Defect Condition When Maintenance is Results Expected When Components Needed Maintenance is Performed General Trash and Trash or debris that is plugging more Barrier cleared to design flow Debris than 20% of the openings in the barrier. capacity. Metal Damaged/ Bars are bent out of shape more than 3 Bars in place with no bends more Missing inches. than 3/4 inch. Bars. Bars are missing or entire barrier Bars in place according to design. missing. Bars are loose and rust is causing 50% Barrier replaced or repaired to deterioration to any part of barrier. design standards. Inlet/Outlet Debris barrier missing or not attached to Barrier firmly attached to pipe Pipe pipe Volume V Runoff Treatment BMPs December 2014 4-39 No. 18 — Catchbasin Inserts Maintenance Defect Conditions When Maintenance is Results Expected When Component Needed Maintenance is Performed General Sediment When sediment forms a cap over the No sediment cap on the insert Accumulation insert media of the insert and/or unit. media and its unit. Trash and Trash and debris accumulates on insert Trash and debris removed Debris unit creating a blockage/restriction. from insert unit. Runoff freely Accumulation flows into catch basin. Media Insert Not Effluent water from media insert has a Effluent water from media Removing Oil visible sheen. insert is free of oils and has no visible sheen. Media Insert Catch basin insert is saturated with water Remove and replace media Water Saturated and no longer has the capacity to insert absorb. Media Insert -Oil Media oil saturated due to petroleum spill Remove and replace media Saturated that drains into catch basin. insert. Media Insert Use Media has been used beyond the typical Remove and replace media at Beyond Normal average life of media insert product. regular intervals, depending on Product Life insert product. Volume V — Runoff Treatment BMPs — December 2014 4-51 Applicable Operational BMPs: • Eliminate unpermitted wastewater discharges to storm sewer, ground water, or surface water. • Convey unpermitted discharges to a sanitary sewer if allowed by the local sewer authority, or to other approved treatment. • Obtain appropriate state and local permits for these discharges. Recommended Additional Operational BMPs: At commercial and industrial facilities, conduct a survey of wastewater discharge connections to storm drains and to surface water as follows: • Conduct a field survey of buildings, particularly older buildings, and other industrial areas to locate storm drains from buildings and paved surfaces. Note where these join the public storm drain(s). During non-stormwater conditions inspect each storm drain for non- stormwater discharges. Record the locations of all non-stormwater discharges. Include all permitted discharges. If useful, prepare a map of each area. Show on the map the known location of storm sewers, sanitary sewers, and permitted and unpermitted discharges. Aerial photos may be useful. Check records such as piping schematics to identify known side sewer connections and show these on the map. Consider using smoke, dye, or chemical analysis tests to detect connections between two conveyance systems (e.g., process water and stormwater). If desirable, conduct TV inspections of the storm drains and record the footage on videotape. • Compare the observed locations of connections with the information on the map and revise the map accordingly. Note suspect connections that are inconsistent with the field survey. Identify all connections to storm sewers or to surface water and take the actions specified above as applicable BMPs. S411 BMPs for Landscaping and Lawn/ Vegetation Management Description of Pollutant Sources: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Lawn and vegetation management can include control of objectionable weeds, insects, mold, bacteria, and other pests with pesticides. Examples include weed control on golf course lawns, access roads, and utility corridors and during landscaping; sap stain and insect control on lumber and logs; rooftop moss removal; killing nuisance rodents; fungicide application to patio decks, and residential lawn/plant care. It is possible to Volume IV - Source Control BMPs —December 2014 2-21 release toxic pesticides such as pentachlorophenol, carbamates, and organometallics to the environment by leaching and dripping from treated parts, container leaks, product misuse, and outside storage of pesticide contaminated materials and equipment. Poor management of the vegetation and poor application of pesticides or fertilizers can cause appreciable stormwater contamination. Pollutant Control Approach: Control of fertilizer and pesticide applications, soil erosion, and site debris to prevent contamination of stormwater. Develop and implement an Integrated Pest Management Plan (IPM) and use pesticides only as a last resort. Carefully apply pesticides/ herbicides, in accordance with label instructions. Maintain appropriate vegetation, with proper fertilizer application where practicable, to control erosion and the discharge of stormwater pollutants. Where practicable grow plant species appropriate for the site, or adjust the soil properties of the subject site to grow desired plant species. Applicable Operational BMPs for Landscaping: • Install engineered soil/landscape systems to improve the infiltration and regulation of stormwater in landscaped areas. Do not dispose of collected vegetation into waterways or storm sewer systems. Recommended Additional Operational BMPs for Landscaping: • Conduct mulch -mowing whenever practicable • Dispose of grass clippings, leaves, sticks, or other collected vegetation, by composting, if feasible. • Use mulch or other erosion control measures on soils exposed for more than one week during the dry season or two days during the rainy season. • Store and maintain appropriate oil and chemical spill cleanup materials in readily accessible locations when using oil or other chemicals. Ensure that employees are familiar with proper spill cleanup procedures. • Till fertilizers into the soil rather than dumping or broadcasting onto the surface. Determine the proper fertilizer application rate for the types of soil and vegetation encountered. • Till a topsoil mix or composted organic material into the soil to create a well -mixed transition layer that encourages deeper root systems and drought -resistant plants. • Use manual and/or mechanical methods of vegetation removal rather than applying herbicides, where practical. Volume IV - Source Control BMPs — December 2014 2-22 Applicable Operational BMPs for the Use of Pesticides: • Develop and implement an IPM (See section on IPM in Applicable Operational BMPse or Vegetation Management) and use pesticides only as a last resort. • Implement a pesticide -use plan and include at a minimum: a list of selected pesticides and their specific uses; brands, formulations, application methods and quantities to be used; equipment use and maintenance procedures; safety, storage, and disposal methods; and monitoring, record keeping, and public notice procedures. All procedures shall conform to the requirements of Chapter 17.21 RCW and Chapter 16-228 WAC (Appendix IV-D R.7). • Choose the least toxic pesticide available that is capable of reducing the infestation to acceptable levels. The pesticide should readily degrade in the environment and/or have properties that strongly bind it to the soil. Conduct any pest control activity at the life stage when the pest is most vulnerable. For example, if it is necessary to use a Bacillus thurin ig ens application to control tent caterpillars, apply it to the material before the caterpillars cocoon or it will be ineffective. Any method used should be site -specific and not used wholesale over a wide area. • Apply the pesticide according to label directions. Do not apply pesticides in quantities that exceed manufacturer's instructions. • Mix the pesticides and clean the application equipment in an area where accidental spills will not enter surface or ground waters, and will not contaminate the soil. • Store pesticides in enclosed areas or in covered impervious containment. Do not discharge pesticide contaminated stormwater or spills/leaks of pesticides to storm sewers. Do not hose down the paved areas to a storm sewer or conveyance ditch. Store and maintain appropriate spill cleanup materials in a location known to all near the storage area. • Clean up any spilled pesticides. Keep pesticide contaminated waste materials in designated covered and contained areas. • The pesticide application equipment must be capable of immediate shutoff in the event of an emergency. • Spraying pesticides within 100 feet of open waters including wetlands, ponds, and rivers, streams, creeks, sloughs and any drainage ditch or channel that leads to open water may have additional regulatory requirements beyond just following the pesticide product label. Additional requirements may include: • Obtaining a discharge permit from Ecology. • Obtaining a permit from the local jurisdiction. • Using an aquatic labeled pesticide. Volume IV - Source Control BMPs — December 2014 2-23 Flag all sensitive areas including wells, creeks, and wetlands prior to spraying. • Post notices and delineate the spray area prior to the application, as required by the local jurisdiction or by Ecology. Conduct spray applications during weather conditions as specified in the label direction and applicable local and state regulations. Do not apply during rain or immediately before expected rain. Recommended Additional Operational BMPs for the use of pesticides: Consider alternatives to the use of pesticides such as covering or harvesting weeds, substitute vegetative growth, and manual weed control/moss removal. • Consider the use of soil amendments, such as compost, that are known to control some common diseases in plants, such as Pythium root rot, ashy stem blight, and parasitic nematodes. The following are three possible mechanisms for disease control by compost addition (USEPA Publication 530-F-9-044): 1. Successful competition for nutrients by antibiotic production; 2. Successful predation against pathogens by beneficial microorganism; and 3. Activation of disease -resistant genes in plants by composts. Installing an amended soil/landscape system can preserve both the plant system and the soil system more effectively. This type of approach provides a soil/landscape system with adequate depth, permeability, and organic matter to sustain itself and continue working as an effective stormwater infiltration system and a sustainable nutrient cycle. • Once a pesticide is applied, evaluate its effectiveness for possible improvement. Records should be kept showing the effectiveness of the pesticides considered. Develop an annual evaluation procedure including a review of the effectiveness of pesticide applications, impact on buffers and sensitive areas (including potable wells), public concerns, and recent toxicological information on pesticides used/proposed for use. If individual or public potable wells are located in the proximity of commercial pesticide applications, contact the regional Ecology hydrogeologist to determine if additional pesticide application control measures are necessary. • Rinseate from equipment cleaning and/or triple -rinsing of pesticide containers should be used as product or recycled into product. For more information, contact the Washington State University (WSU) Extension Home -Assist Program, (253) 445-4556, or Bio-Integral Resource Center (BIRC), P.O. Box 7414, Berkeley, CA.94707, or EPA to Volume IV - Source Control BMPs — December 2014 2-24 obtain a publication entitled "Suspended, Canceled, and Restricted Pesticides " which lists all restricted pesticides and the specific uses that are allowed. Applicable Operational BMPs for Vegetation Management: Use at least an eight -inch "topsoil' layer with at least 8 percent organic matter to provide a sufficient vegetation -growing medium. Amending existing landscapes and turf systems by increasing the percent organic matter and depth of topsoil can substantially improve the permeability of the soil, the disease and drought resistance of the vegetation, and reduce fertilizer demand. This reduces the demand for fertilizers, herbicides, and pesticides. Organic matter is the least water-soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually, and this release corresponds closely to the plant growth cycle. Return natural plant debris and mulch to the soil, to continue recycling nutrients indefinitely. Select the appropriate turfgrass mixture for the climate and soil type. Certain tall fescues and rye grasses resist insect attack because the symbiotic endophytic fungi found naturally in their tissues repel or kill common leaf and stem -eating lawn insects. However, they do not, repel root -feeding lawn pests such as Crane Fly larvae, and are toxic to ruminants such as cattle and sheep. The fungus causes no known adverse effects to the host plant or to humans. Endophytic grasses are commercially available; use them in areas such as parks or golf courses where grazing does not occur. Local agricultural or gardening resources such as Washington State University Extension office can offer advice on which types of grass are best suited to the area and soil type. • Use the following seeding and planting BMPs, or equivalent BMPs to obtain information on grass mixtures, temporary and permanent seeding procedures, maintenance of a recently planted area, and fertilizer application rates: Temporary and Permanent Seeding, Mulching, Plastic Covering, and Sodding as described in Volume II. Adjusting the soil properties of the subject site can assist in selection of desired plant species. For example, design a constructed wetland to resist the invasion of reed canary grass by layering specific strata of organic matters (e.g., composted forest product residuals) and creating a mildly acidic pH and carbon -rich soil medium. Consult a soil restoration specialist for site -specific conditions. • Aerate lawns regularly in areas of heavy use where the soil tends to become compacted. Conduct aeration while the grasses in the lawn are growing most vigorously. Remove layers of thatch greater than 3/4-inch deep. Volume IV - Source Control BMPs —December 2014 2-25 Mowing is a stress -creating activity for turfgrass. Grass decreases its productivity when mown too short and there is less growth of roots and rhizomes. The turf becomes less tolerant of environmental stresses, more disease prone and more reliant on outside means such as pesticides, fertilizers, and irrigation to remain healthy. Set the mowing height at the highest acceptable level and mow at times and intervals designed to minimize stress on the turf. Generally mowing only 1/3 of the grass blade height will prevent stressing the turf. Irrigation: The depth from which a plant normally extracts water depends on the rooting depth of the plant. Appropriately irrigated lawn grasses normally root in the top 6 to 12 inches of soil; lawns irrigated on a daily basis often root only in the top 1 inch of soil. Improper irrigation can encourage pest problems, leach nutrients, and make a lawn completely dependent on artificial watering. The amount of water applied depends on the normal rooting depth of the turfgrass species used, the available water holding capacity of the soil, and the efficiency of the irrigation system. Consult with the local water utility, Conservation District, or Cooperative Extension office to help determine optimum irrigation practices. Fertilizer Management: Turfgrass is most responsive to nitrogen fertilization, followed by potassium and phosphorus. Fertilization needs vary by site depending on plant, soil, and climatic conditions. Evaluation of soil nutrient levels through regular testing ensures the best possible efficiency and economy of fertilization. For details on soils testing, contact the local Conservation District, a soils testing professional, or a Washington State University Extension office. Apply fertilizers in amounts appropriate for the target vegetation and at the time of year that minimizes losses to surface and ground waters. Do not fertilize when the soil is dry. Alternatively, do not apply fertilizers within three days prior to predicted rainfall. The longer the period between fertilizer application and either rainfall or irrigation, the less fertilizer runoff occurs. Use slow release fertilizers such as methylene urea, IDBU, or resin coated fertilizers when appropriate, generally in the spring. Use of slow release fertilizers is especially important in areas with sandy or gravelly soils. Time the fertilizer application to periods of maximum plant uptake. Ecology generally recommends application in the fall and spring, although Washington State University turf specialists recommend four fertilizer applications per year. Volume IV - Source Control BMPs —December 2014 2-26 • Properly trained persons should apply all fertilizers. Apply no fertilizer at commercial and industrial facilities, to grass swales, filter strips, or buffer areas that drain to sensitive water bodies unless approved by the local jurisdiction. Integrated Pest Management An IPM program might consist of the following steps: Step 1: Correctly identify problem pests and understand their life cycle Step 2: Establish tolerance thresholds for pests. Step 3: Monitor to detect and prevent pest problems. Step 4: Modify the maintenance program to promote healthy plants and discourage pests. Step 5: Use cultural, physical, mechanical or biological controls first if pests exceed the tolerance thresholds. Step 6: Evaluate and record the effectiveness of the control and modify maintenance practices to support lawn or landscape recovery and prevent recurrence. For an elaboration of these steps, refer to Appendix IV-F. S412 BMPs for Loading and Unloading Areas for Liquid or Solid Material Description of Pollutant Sources: Operators typically conduct loading/unloading of liquid and solid materials at industrial and commercial facilities at shipping and receiving, outside storage, fueling areas, etc. Materials transferred can include products, raw materials, intermediate products, waste materials, fuels, scrap metals, etc. Leaks and spills of fuels, oils, powders, organics, heavy metals, salts, acids, alkalis, etc. during transfer may cause stormwater contamination. Spills from hydraulic line breaks are a common problem at loading docks. Pollutant Control Approach: Cover and contain the loading/unloading area where necessary to prevent run-on of stormwater and runoff of contaminated stormwater. Applicable Operational BMPs: At All Loading/ Unloading Areas: • A significant amount of debris can accumulate at outside, uncovered loading/unloading areas. Sweep these surfaces frequently to remove loose material that could contaminate stormwater. Sweep areas temporarily covered after removal of the containers, logs, or other material covering the ground. • Place drip pans, or other appropriate temporary containment device, at locations where leaks or spills may occur such as hose connections, hose reels and filler nozzles. Always use drip pans when making and Volume IV - Source Control BMPs — December 2014 2-27 Hill Residence Civil - 20439 June 2, 2021 Drainage Report Section VII, Page 4 Figure VII-1. Map of project area. CM 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Hill Residence Civil - 20439 Drainage Report June 2, 2021 Section VI I, Page 5 SAMPLE ACTIVITY LOG DATE FACILITY MAINTENANCE PERFORMED RESULTS / NOTES 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com