The URL can be used to link to this page

DNS BLD2022-0254+Storm_Drainage_Report+2.25.2022_7.11.21_PM+2704407Imm engineering pllc RECEIVED O W04M BLD2022-0254 CITY OF EDMONDS f1FVFl fl PRAFNT Main Street Commons Commercial Development 550 Main Street Edmonds, WA 98020 Stormwater Site Plan May 7, 2019, Revised December 11, 2019, January 14, 2020, April 10, 2020 and February 25, 2022 The information contained in this report was prepared by and under the direct supervision of the undersigned: PA1VG�t A$,s 4 S'CR�� ww� sSJONAL �� LPD Engineering, PLLC 1932 1,,Ave, Suite 201 Seattle,WA 98101 Contact: Sarah Pangelinan, P.E. (206)725-1211 2I2�f �22 Prepared for: DiMarco Architecture 1319 E Howell Street Seattle,WA 98122 Contact: David J. DiMarco,AIA, CPHC (206) 285-0400 mmm engineering pllc MAIN STREET COMMONS COMMERCIAL DEVELOPMENT PROJECT STORMWATER SITE PLAN TABLE OF CONTENTS SectionI — Project Overview................................................................................................................................................ Section 2 — Existing ConditionsSummary.......................................................................................................................... Section3 — Offsite Analysis.................................................................................................................................................... 2 Section 4 — Minimum Requirements.................................................................................................................................... 3 Section 5 — Permanent Stormwater Control Plan............................................................................................................6 Section 6 — Construction Stormwater Pollution Prevention Plan(SWPPP)............................................................ 13 Section 7 — Other Reports and Studies............................................................................................................................. 14 Section8 — Other Permits................................................................................ Section 9 — Operation and Maintenance Manual............................................................................ Section 10 — Bond Quantities Worksheet....................................................................................... FIGURES Figure I: Vicinity Map Figure 2: Soils Map Figure 3: Downstream Drainage Map Figure 4: Existing Conditions Figure 5: Proposed Conditions APPENDICES Appendix A — *MOVED TO DRAWING SET* Appendix B — Design Calculations and Supporting Information Appendix C — Construction Stormwater Pollution Prevention Plan (SWPPP) Narrative Appendix D — Geotechnical Report Appendix E — Operations and Maintenance Manual Appendix F — Bond Quantity Worksheet mmm engineering pllc MAIN STREET COMMONS COMMERCIAL DEVELOPMENT PROJECT STORMWATER SITE PLAN MAY 7, 2019, REVISED DECEMBER 119 2019, JANUARY 14, 2020, APRIL 10, 2020 AND FEBRUARY 25, 2022 SECTION I - PROJECT OVERVIEW This Stormwater Site Plan is for the Main Street Commons Commercial Development Project. The site is located at 550 Main Street in Edmonds, Washington; Section 24, Township 27 North, Range 3 East, Willamette Meridian. Refer to Figure 1 — Vicinity Map for site location. This project will involve the renovation of the existing on -site building to remain to accommodate space for a restaurant, retail businesses and courtyard area; construction of a new two-story commercial building in the eastern portion of the site to primarily serve retail tenants; and construction of a courtyard area in the remaining site area. Within the courtyard area a structure for the City of Edmonds Historic Fire Truck display will be provided. Parking for the development will include 8 parking stalls located along the southern property boundary to be accessed from the alley. There are currently no flow control facilities associated with the existing impervious areas at the site. This Stormwater Site Plan addresses the requirements of the 2017 Edmonds Stormwater Addendum (ESA) and Chapter 18.30 of the Edmonds Municipal Code. The 2017 ESA supplements the Department of Ecology (DOE) 2012 Stormwater Management Manual for Western Washington (SWMMWW), amended in 2014. SECTION 2 - EXISTING CONDITIONS SUMMARY The project is located on two parcels (#00434212001700 and #00434212001500), with an area of approximately 0.45-acres (19,602 sf). The corner parcel is approximately 0.30-acres (13,068 sf) and the westerly parcel is approximately 0.15-acres (6,534 sf). The site currently consists of a surface parking lot encompassing the east portion of the site and an approximately 6,900 sf commercial building on the western parcel. The property is bounded by 6t1i Avenue S to the east, Main Street to the north, an alley to the south, and a commercial/retail structure to the west. The total project disturbance area is approximately 14,950 square feet (0.34 acres). Refer to Figure 4 — Existing Conditions. The topography of the corner parcel, currently developed with a surface parking lot, slopes to the west from a high elevation point of approximately 92-feet to a low point of 86-feet. The existing building on the parcel adjacent to the west has a zero -lot line, and thus, topographically, the parcel is fully developed and relatively flat. According to maps of the City's drainage basins, the site is located in the Shellabarger watershed. Runoff from the existing surface parking lot sheet flows to the west draining to a series of storm inlets which discharge to the public storm drainage system via a 6-inch conveyance pipe at an existing catch basin located on the south side of Main Street. Runoff from the western half of the existing building roof is collected in a downspout which discharges to the alley at the southwest mmm engineering pllc corner of the building. Runoff from the eastern half of the existing building roof is currently collected via downspouts and conveyed via the onsite stormwater system to the public storm system in Main Street. Within the public system, stormwater is conveyed further west, then south eventually discharging into Shellabarger Creek, which flows into Edmonds Marsh ultimately outfalling into the Puget Sound. See the Offsite Analysis section of the report for more information on the downstream drainage course. A geotechnical report was prepared by PanGeo, dated November 4, 2018. Their subsurface exploration observed existing generally dense fill up to 4-feet thick overlying medium dense to dense native soils consisting of medium dense to very dense, silty fine to medium sand with gravel and very dense, silty fine sand with pebble -sized gravels. According to the geotechnical report the silty fine to medium sand with gravel appeared consistent with mapped Transitional Beds at the site, and the silty fine sand with pebble -sized gravels appeared consistent with Olympia Gravel mapped in the area just north of the site. Refer to Figure 2 — Soils Map. SECTION 3 - OFFSITE ANALYSIS The following is a qualitative downstream analysis, performed in accordance with the 2017 City of Edmonds Stormwater Addendum. The site area of this project is comprised of the existing building, which is located in the western portion of the property, and a parking lot located in the eastern portion of the property. The site is located in the Shellabarger watershed according to maps of the city's drainage basins. Runoff form the site is generated from the existing surface parking lot and the existing building. Stormwater runoff from the parking lot sheet flows to the western half of the existing building drain to the public storm system in Main Street. The stormwater then conveys as follows: 1) West on Main Street for approximately 650 feet. 2) Thence South along 5t' Avenue South for approximately 300 feet. 3) Thence West along Dayton Street for approximately 675 feet. 4) Thence South along 3' Avenue South for approximately 1,100 feet where it then proceeds West into Shellabarger Creek. Stormwater then discharges into the Puget Sound, approximately %2 of a mile from where it discharged into Shellabarger Creek. Stormwater runoff from the eastern half of the building is discharged to the ground surface via a downspout at the southwest corner of the existing building. The stormwater is then conveyed as follows: 1) Sheet flows in alley approximately 340 feet to an existing catch basin in the alley. 2) Thence conveyed in the public storm system west to the storm main in 5t1i Avenue South for approximately 90 feet where it combines with the stormwater from the western portion of the site. 3) The stormwater then continues as described in number 3 and 4 above. LPD Engineering, PLLC Page 2 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc Based on correspondence with the City of Edmonds there are no known stormwater issues or complaints on record for the stormwater system downstream of the site. However, the City did confirm that the stormwater system in Main and 5' is generally believed to be very near capacity. It is expected that proposed stormwater improvements will attenuate stormwater runoff rates from the site. The project will be reducing the amount of impervious area on the site by providing areas of landscaping, providing flow control for all new and replaced impervious surfaces and providing flow control for 25% of the existing uncontrolled impervious surfaces to remain. SECTION 4 - MINIMUM REQUIREMENTS The project classification and minimum requirements are determined per Figure 3.1 of the Edmonds Stormwater Addendum, which applies for any project development. The project will involve more than 5,000 square feet (SF) of new plus replaced hard surfaces and is not a road - related project. Therefore, the project is a Category 2 project per section 3.1.3(1) of the Edmonds Stormwater Addendum and according to Figure 3.1, all minimum requirements (#149) apply to the new and replaced hard surfaces and converted vegetation areas. See description of minimum requirements for further explanation. Below is a list of the Minimum Requirements and a brief description of how they are addressed in this project: • Minimum Requirement #1: Preparation of Stormwater Site Plan This document is the Stormwater Site Plan. It outlines the existing and proposed site and drainage conditions, describes the flow control systems, and presents the stormwater analysis. Minimum Requirement #2: Construction Stormwater Pollution Prevention The Construction Stormwater Pollution Prevention Plan (SWPPP) is attached in Appendix C and addressed in Section 6 of this report. This documentation supplements the Temporary Erosion and Sediment Control (TESC) Plans, which is on sheet C 1.0 of the plan set included in Appendix A. The project will not disturb more than one acre of land; therefore, a Construction Stormwater General Permit from the Department of Ecology will not be required. • Minimum Requirement #3: Source Control of Pollution None of the activities listed in Volume IV of the 2014 DOE Manual are applicable to this project. The project will have to adhere to the BMPs for S411, Landscaping and Lawn/Vegetation Management, as source control for landscaped areas. Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls The proposed improvements will not alter the existing downstream path. Stormwater will continue to be routed to the existing public storm systems in Main Street and the adjacent alley. From there, the same downstream drainage path to Shellabarger Creek will be maintained in the proposed conditions. It is expected that proposed stormwater improvements will attenuate runoff rates from the site. LPD Engineering, PLLC Page 3 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc Figure 3.1 from the 2017 Edmonds Stormwater Addendum EDMONDS STORMWATER ADDENDUM JUNE 2017 Does the project result m 2 000 square feet, or greater. of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square feet or greater? Yes No Minimum Requirements No. l through 5 apply I Minimum Requirement No. 2 applies Next Question Does 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 more of native vegetation to pasture'? No is this a road related project'? Yes All Minimum Requirements apply to the new and replaced Yea hard surfaces and converted vegetation areas. All Minimum Requirements apply to the new hard surfaces and converted vegetation areas. No Does the project add 5,lx)n square feet or No more of new hard surfaces? Yes Do new hard surfaces add 50" o or more to the existing hard surfaces within the project limits' No F igure 3.1. Flow Chart for Determining Requirements for Development. INo additional requirements. LPD Engineering, PLLC Page 4 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc Minimum Requirement #5: Onsite Stormwater Management On -site Stormwater Management will be required for the project as the project will result in more than 2,000 SF or new and replaced hard surfaces. This project is a Category 2 project and therefore must evaluate List No. 2 from the 2014 DOE Manual for each new or replaced lawn, landscaped, roof or hard surface. BMP T5.13 Post -Construction Soil Quality and Depth (found in Volume V of the 2014 DOE Manual) will be implemented in all new or replaced pervious (landscaping/lawn) areas. The new and replaced pervious areas include new landscape planting areas within the site. For more information on the implementation of on -site stormwater management BMPs, see Section 5 of this report. Additionally, as the project includes existing hard surfaces that do not drain to an approved stormwater management facility and the project drains directly to the City of Edmond's MS4 public storm system, the project is required to manage a minimum of 25 percent of those existing hard surfaces that will remain after the project. Refer to the On -site Stormwater Management Section for more information. Minimum Requirement #6: Runoff Treatment Runoff treatment will not be required for the project. The project proposes less than 5,000 SF of pollution -generating hard surface (PGHS) and less than 3/4 of an acre of pollution - generating pervious surfaces (PGPS). Therefore, per section 2.5.6 of the DOE manual Runoff Treatment is not required. However, per section 5.6.1 of the Edmonds Stormwater Addendum, since the project is not zoned as single-family residential and will collect runoff from five or more parking spaces, the project is required to install floatable controls in catch basins, or another floatable control system. Refer to the Runoff Treatment Section for more information. Minimum Requirement #7: Flow Control Flow control will be required for the project as the project will result in more than 10,000 SF of new and replaced hard surfaces. Flow control for the project area will be provided via a detention vault and flow control structure located within the courtyard between the existing building and the proposed building. Additionally, as the project includes existing hard surfaces that do not drain to an approved stormwater management facility and the project drains directly to the City of Edmond's MS4 public storm system, the project is required to manage a minimum of 25 percent of those existing hard surfaces that will remain after the project. Refer to the On -site Stormwater Management Section and the Flow Control Section for more information. • Minimum Requirement #8: Wetland Protection There are no wetlands within or adjacent to the site. • Minimum Requirement #9: Operation and Maintenance An Operations and Maintenance Manual for the project has been prepared and is attached in Appendix D of this report. A draft Declaration of Covenant for Low Impact Development Stormwater Systems is not provided as part of this Stormwater Site Plan as there are no Low Impact Development facilities proposed for the project. LPD Engineering, PLLC Page 5 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc SECTION 5 - PERMANENT STORMWATER CONTROL PLAN The project will propose more than 10,000 square feet of effective impervious surface in a threshold discharge area, and therefore on -site stormwater management and flow control are required. Per the DOE Manual, section 2.5.7, for the new and replaced hard surface and converted vegetation areas, the flow control facility must be designed such that the proposed discharge durations match the existing/predeveloped discharge durations for the range of flows from 50% of the 2-year flow through the 50-year flow. Existing/predeveloped conditions are to be modeled as forested land cover. The project will not result in more than 5,000 square feet of pollution generating hard surfaces or more than 3/4 acre of pollution generating pervious surfaces; therefore, sizing of a water quality treatment facility is not required and has not been included in the proposed stormwater design. As noted above, the project is required to address all minimum requirements (#1-9) for new plus replaced hard surfaces and converted vegetation areas. For minimum requirement #7, these surfaces are to be mitigated by flow control and are therefore designated as the "target surfaces." Within the project area the existing building roof is an unmanaged hard surface that will remain after project completion. Per Edmonds City Code section 18.30.060.5.b.8, projects discharging to the City's MS4 must mitigate at least 25% of the existing unmanaged hard surfaces that will remain. The majority of the existing building roof is routed to the east side of the building where it discharges to the existing site storm drainage system. In the proposed condition this will continue and the roof runoff will be routed to the proposed vault. As required by the City the vault and flow control design will include 25% of the existing building roof in the target surfaces. The remaining roof area routed the vault will be included as pass -through, this roof area is modeled as impervious surface in both the pre -developed and developed conditions. The following table describes the target surfaces that must be mitigated. The target surfaces include the new and replaced impervious surfaces, such as pavement, roofs, and existing unmanaged impervious surfaces such as roofs. The project does not include any converted vegetation areas therefore pervious landscape areas have not been included in the Target surfaces. Refer to Figure 5 — Proposed Conditions for more information on the proposed areas used for the stormwater model. Table 1— Target Surfaces Square Feet Acres Proposed Building Roof 3,959 0.091 Asphalt/Concrete Pavement (PGIS) 1,335 0.030 Standard Concrete Pavement (NPGIS) 6,386 0.147 Total New Plus Replaced Hard Surface TARGET SURFACE 11,680 0.268 As shown above in Table 1 and in the attached Figure 5 — Proposed Conditions, the target surface is 0.268 acres, which will require flow control mitigation to historical/forest conditions. The target surface is the minimum amount of area that is to be mitigated to the forested duration match criteria. As stated above, flow control mitigation to historical/forested conditions will also be provided for 25% of the existing building roof to remain. Due to the design of the existing building LPD Engineering, PLLC Page 6 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc roof an additional 3,645 SF of the existing roof area will be included in the detention vault basin area but are not required to be included as target surfaces. This area will be entered as a Pass - through basin in the detention model and is also identified on Figure 5 — Proposed Conditions. The project proposes an onsite detention vault located in the central courtyard area. The detention vault will have a flow control structure, equipped with a riser (with multiple orifices) to manage the stormwater flows. Due to the existing invert elevation at the connection to the public storm system in Main Street a pump system will be designed downstream of the flow control structure. The pump system will discharge flows to an onsite structure downstream of the pump structure before stormwater flows gravity flow to an existing catch basin located in the Main Street right-of-way The project also includes approximately 0.036 acres (1,582 SF) of new concrete sidewalk along Main St and 6t' Avenue South and asphalt in the alley. An additional 0.009 acres (373 SF) of asphalt will be removed and replaced in the alley for utility trenching and connection to existing utilities. These surfaces could not be routed to the proposed detention facility but are mitigated by the detention facility and have been included in the stormwater model as bypass areas. Pre -developed Site Hydrology Refer to the offsite analysis section of this report for a detailed description of the existing drainage conditions. Runoff from the overall site is primarily generated from the existing building and the surface parking lot. Stormwater runoff from the site conveys northerly and westerly towards the public storm drainage systems in Main Street and 5t' Avenue South. The stormwater is conveyed in Shellabarger Creek and is eventually discharged into the Puget Sound. Proposed Site Hydrology The overall drainage pattern throughout the site is not being changed by the proposed improvements. There will be one flow control structure designed to attenuate runoff rates from the site. There will be one connection point to the existing storm system in Main Street and the north western corner of the existing building will continue to discharge to the alley. Rain falling upon the proposed roof area will be collected in downspouts and conveyed in underground pipe to the detention vault. Similarly, rain falling on the proposed onsite concrete and asphalt pavement areas will be collected in catch basins, area drains and trench drains and conveyed in underground pipe to the detention vault. The flow control structure is designed to release stormwater at the allowable rates modeled by the MGS Flood program with the Puget East 36 time series, as outlined by section 2.1 of the 2017 Edmonds Stormwater Addendum. The system is designed to meet the standard flow duration standard, comparing the predeveloped stormwater discharges to the developed discharges for the range of 50% of the 2-year peak flow up to the full 50-year peak flow. On -Site Stormwater Management (MR #5) Per section 5.5 of the 2017 Edmonds Stormwater Addendum, on -site stormwater management best management practices (BMPs) must be implemented per List #2 of the DOE manual unless infeasibility criteria (from Appendix A of the 2017 ESA) can be provided for each BMP. This project is proposing to use compost amended soil (BMP T5.13) for new landscape areas, which is the only feasible on -site stormwater management BMP. See geotechnical report in Appendix D. LPD Engineering, PLLC Page 1 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc The following table shows the List #2 on -site stormwater management BMPs and whether or not they will be feasible for this project. Table 2 — On -Site Stormwater Management BMP Evaluation BMP Feasibility Explanation Lawn/Landscaped Areas Post -Construction Yes Post -Construction Soil Quality and Depth per BMP T5.13 will be utilized Soil Quality and for all proposed landscape areas. Depth Roo s Full Dispersion No A minimum forested or native vegetation flowpath length of 100 feet (25 feet for sheet flow from a nonnative pervious surface) cannot be achieved. Downspout Full No Based on geotechnical evaluation, infiltration is not recommended for this Infiltration Systems site. Downspout full infiltrations stems would not be recommended. Bioretention / Rain No Based on geotechnical evaluation, infiltration is not recommended for this Gardens site. Infiltration rate of 0.3 inches per hour could not be achieved. Downspout infiltrations stems would not be recommended. Downspout No The proposed roof area does not have a 25-foot vegetated flowpath from Dispersion Systems the downspout locations the property line. Perforated Stub -Out No Based on geotechnical evaluation, infiltration is not recommended for this Connections site. Perforated stub -out connections would not be recommended. Detention Vaults and Yes A detention system is provided, though it has been sized to meet Pipes minimum requirement #7-Flow Control and not On -site Stormwater Management. Other Hard Surfaces Full Dispersion No A minimum forested or native vegetation flowpath length of 100 feet (25 feet for sheet flow from a nonnative pervious surface) cannot be achieved. Permeable Pavement No Based on geotechnical evaluation, infiltration is not recommended for this site. Permeable Pavement is not recommended. Bioretention / Rain No Based on geotechnical evaluation, infiltration is not recommended for this Gardens site. Downspout infiltrations stems would not be recommended. Sheet Flow No Positive drainage for sheet flow cannot be achieved and a 10-foot wide Dispersion vegetation buffer for every 20 feet of contributing surface cannot be achieved. Concentrated Flow No A minimum vegetated flowpath of 50 feet for rock pads or 25 feet for Dis ersion dispersion trenches cannot be met. Detention Vaults and Yes A detention system is provided, though it has been sized to meet Pipes minimum requirement #7-Flow Control and not On -site Stormwater Management. Water Quality (MR #6) As stated above in Section 4 the project proposes less than 5,000 SF of pollution -generating hard surface (PGHS) and less than % pf am acre of pollution -generating pervious surface (PGPS). The pollution generating hard surfaces for the project are limited to eight (8) parking stalls located adjacent to the alley at the south side of the property. This results in approximately 1,701 SF of PGHS. The PGPS for the project are limited to new landscaped areas which total approximately 638 SF. LPD Engineering, PLLC Page 8 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc Per section 5.6.1 of the Edmonds Stormwater Addendum, since the project is not zoned as single- family residential and will collect runoff from five or more parking spaces, the project is required to install floatable controls in catch basins, or another floatable control system. The stormwater runoff from the parking stalls will be collected by a trench drain and conveyed to the detention vault. Overall oil and floatable control for the site is provided by the 6" riser structure included in the flow control structure downstream of the detention vault. Flow Control System (MR #7) Flow control is required for the project as it will result in greater than 10,000 SF of new plus replaced hard surface. Flow control should be provided for all target areas which are summarized in Table 1 above and shown in Figure 5 — Proposed Conditions. Additionally, Per Edmonds City Code section 18.30.060.5.b.8, projects discharging to the City's MS4 must mitigate at least 25% of the existing unmanaged hard surfaces that will remain. Within the project area the existing building roof area is currently unmanaged and will remain after the project is completed. Therefore, the flow control system will be designed to provide flow control for 25 percent of the existing building roof area. A detention vault and a multiple orifice flow control structure will be designed to meet the required flow control for the project. Per Section 2.5.7 of the SWMMWW the flow control system for the project shall be designed to match the developed durations to pre -developed durations for the range of pre -developed discharge rates from 50% of the 2-year peak flow up to the full 50-year peak flow. The modeled pre - developed condition shall be a forested land cover. The flow control facilities have been modeled using MGS Flood with the 15-minute time series. Refer to the output from MGS Flood in Appendix B for detailed stormwater modeling calculations. Due to the design of the existing roof, in order to capture runoff from 25 percent of the existing roof area and convey it to the proposed flow control system, downspouts on the eastern side of the existing building will be tightlined to the new flow control system. This will result in runoff from a majority of the existing roof area being conveyed to the flow control system. The additional roof area beyond 25% will be modeled as pass -through area and is entered in the model as pre - developed impervious area and developed impervious area. Additionally, new pervious surfaces are not included in the required target surfaces and are therefore entered as pre -developed grass area. A summary of tributary areas and bypass areas used in sizing the flow control system is provided in Table 3 below. LPD Engineering, PLLC Page 9 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 Imm engineering pllc Table 3 — Flow Control Basin Square Feet Acres Proposed Building Roof 3,959 0.091 Asphalt/Concrete Pavement (PGIS) 1,335 0.030 Standard Concrete Pavement (NPGIS) 6,386 0.147 TOTAL ONSITE TARGET SURFACES 11,680 0.268 Offsite Asphalt Pavement (PGIS) (BYPASS) 464 0.011 Offsite Concrete Walkways (NPGIS) (BYPASS) 1,582 0.0036 TOTAL OFFSITE TARGET SURFACES 2.046 0.047 TOTAL TARGET SURFACES 13.694 0.314 25% of Existing Building Roof 1,845 0.042 New landscape (Pervious Surface) 606 0.014 Existing Building Roof (PASSTHROUGH) 3,645 0.084 TOTAL BASIN AREA 19.822 0.455 Refer to Illustration 1 below for layout of the MGS Flood postdeveloped scenario setup. LPD Engineering, PLLC Page 10 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 Imm engineering pllc Illustration 1 — Postdeveloped Scenario >; `_renario 2: Postdeveloped I Right Ulick Icons to Impo ' ICopy mage Objects Subbasin Copy Structure ® Open Channel Infilt Trench Developed Site 2510 o Ex Bldg Roof User Rating ® Splitter Ex Bldg Roof BYPASS t\ CAVFS bw Filter Strip Bioretention Detention Vault INPorous Pavement Frontage Bypass New Copy Lnk2 The duration curves from MGS Flood are shown below on Graph 1. Note that the Detention Vault developed discharge flow durations do not exceed the predeveloped forested condition flow durations for the range of 50% of the 2-year storm event to the 50-year storm event. Therefore, the project meets the Peak Flow Control Standard as designated by the SWMMWW Minimum Requirement #7. LPD Engineering, PLLC Page I I Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc Graph 1— Flow Duration Plot Flow Duration Plot 0.1 LL ODS OID L_ 1 Debi low Control Performance �(oursion at 50%02: -73.1 % PASS �Kcursion 5096Q2 to Q2: -73.1 % PASS �ccursion 02 to 050: -91.9% PASSI II Pos Excursion Q2to Q50:0.0°� PA Ilk-0 Ilk-0 1 DB-0I l a-W Ilk-W 1 DB-01 1Ik+EU Exceedance Probability / Predeveloped / Postdeveloped The required detention volume at the riser crest per the MGS model is 3,990 CF. The proposed detention vault is located beneath the proposed concrete plaza area and will be 14' wide by 52' long by 6' deep (active storage depth) resulting in 4,368 CF at the riser crest. The detention vault will discharge via a flow control structure to the northwest. Following the flow control structure, stormwater discharges from the vault will be pumped into the public stormwater system in Main Street. Refer to the design drawings provided in Appendix A for the detail of the detention system and flow control structure. Pump Design As mentioned, the stormwater from the proposed detention vault will have to be pumped due to the existing storm system in Main Street being very shallow, thus not allowing gravity discharge of stormwater directly from the vault. The pump basin will be located downstream of the vault, with a westbound force main taking stormwater to a downstream storm structure located on -site. From the downstream structure stormwater flows will gravity flow to an existing catch basin located in the Main Street right-of-way. The above model was set up to include the pump basin with the point of compliance at the discharge point from the pump basin. See Appendix B for the pump design calculations. LPD Engineering, PLLC Page 12 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc The flow used for the pump selection was the 100-year peak flow from the vault (17.24 gallons per minute). A duplex pump system is required for redundancy, so the maximum flow was determined to be 70 gallons per minute. Additionally, the sump within the basin itself was evaluated to ensure that there is enough volume to handle large storm events and prevent the constant turning off/on of the pumps, which will cause them to wear faster. The pump basin will be equipped with a 6-inch overflow that will gravity discharge to the downstream structure. The force main will connect downstream of the pump basin into the overflow pipe. This will protect against pump failure and overflow events. See the pump detail on Sheet C-2.2 of Appendix A for more information. Conveyance System Analysis and Design An analysis of the onsite conveyance system was performed for the 6-inch outlet from the pump basin. The 2014 DOE manual only requires analysis for the 25-year peak storm for new conveyance systems. However, the pipe analyzed will be compared to the 100-year peak runoff rate as well. These peak flows will be determined using MGS Flood with 15-minute time steps. This was compared to the full -flow capacity of the conveyance pipe, which was determined using Manning's equation. Refer to Appendix B for the Conveyance Analysis Spreadsheet and associated MGS Flood reports. A conveyance analysis was performed for the 6-inch gravity outlet from the pump basin. The detention basin is shown on Figure 5 — Proposed Conditions, and includes the project area and 50% of the existing building roof. The 6-inch pipe (n=0.012) with a proposed slope of 0.6% has a capacity of 0.47 cfs. The peak flow from the 25-year storm event was found to be .267 cfs, and the 100-year storm peak undetained flow is 0.409 cfs. Therefore, the 6-inch pipe has sufficient conveyance capacity for the proposed design even if the pumps are not functioning. SECTION 6 - CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN (SWPPP) The SWPPP narrative for this project can be found in Appendix C. The preliminary SWPPP is based on Volume II of the 2014 DOE Stormwater Management Manual requirements. The TESC plan includes temporary sediment settling tanks. A minimum volume was calculated using the methodology from the 2014 DOE manual, with the 2-year developed flow rate from MGS Flood. A volume of an equivalent sediment trap was calculated to find the necessary volume for sediment tank(s) for this project. A copy of the Sediment Tank Sizing Calculations worksheet used for this exercise is attached in Appendix B. Stormwater runoff from the project work area will sheet flow toward the existing stormwater structures located east of the existing building. Then stormwater will be pumped from one of the existing structures to the temporary sediment settling tank located to the east of the project area. In addition to the sediment settling tanks, TESC elements in the project include the following: LPD Engineering, PLLC Page 13 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc Temporary Stabilized Construction Entrance, per BMP C 105- the contractor will use the existing driveway and asphalt pavement for construction access and will provide a stabilized construction entrance per BMP C105 as needed to prevent sediment trackout. Catch Basin Filters, per BMP C220 Temporary silt dikes for perimeter control. The TESC elements shown are intended to be the minimum allowable. Periodic inspection of the TESC elements will be completed by the contractor to confirm they are holding up and continuing to function as intended. During construction, the contractor is responsible for upgrading these facilities as necessary. The implementation of the TESC plan and construction maintenance, replacement and upgrading of the TESC facilities are the responsibility of the contractor, per the contract documents. The TESC facilities will be constructed prior to and in conjunction with all clearing and grading activity and in a manner in which sediment or sediment laden water does not leave the project site, enter the drainage system, or violate applicable water quality standards. SECTION % - OTHER REPORTSAND STUDIES A geotechnical report was prepared by PanGeo, dated November 4, 2018 and is located in Appendix D of this report. SECTION H - OTHER PERMITS Since the project involves less than 1 acre of land disturbance, an NPDES permit will not be required. SECTION 9 - OPERATION AND MAINTENANCE MANUAL Recommended operations and maintenance guidelines for the stormwater drainage facilities located within the project are provided in Appendix E of this report. SECTION 10 - BOND QUANTITIES WORKSH EET The Bond Quantities Worksheet is attached in Appendix F. LPD Engineering, PLLC Page 14 Main Street Commons Commercial Development Stormwater Site Plan, May 1, 2019, Revised Dec 11, 2019, Jan 14, 2020, April, 10, 2020, and February 25, 2022 mmm engineering pllc FIGURES Figure 1: Vicinity Map Figure 2: Soil Map Figure 3: Downstream Drainage Map Figure 4: Existing Conditions Figure 5: Proposed Conditions z 0 LUZJ GLEN ST iQ IN � F� DAL STDAL Y ST D ALEY S DALEY S eF� 2 SPRA UE ST D _ O� �J�� S Iv-S m m EDMONDS ST Z EDMOND ST ° co ST ry BELL T BELL ST BELL ST cn c E ✓q �4 F `�S'T MAIN ST D 11-- MAIN ST MAIN ST > Q �m z z m ° DAY ON ST DAYTON ST D DAYTON T m m z w (n MAPLE STD MAPLE ST MAPLES w D m ALDE ST D m PROJECT SITE Z ffl o N m = ALDER ST ALDER S cn D m cn m cn cn WAL UT ST cn WALNUT ST WALN T ST WALNUT ST N Uj ° Q 1 M HOLLY DR a, CEDAR ST J 1 = HOWELL WAY HO ELL WAY m MAGNOLIA DR w D cn HOMELAND DIP SPRUCE T > m D m = HEMLOC ST J rn HEMLOCK AY D m LAUREL WAY ERBEN R LAUREL ST 00 1 w SEAMONT LANE _ ° PINE ST < PIN ST PINE ST < JPINEST PINE ST ccn PINE ST cn ,ViVA\ILj�1■,L»tt�1iViV�VATM1►�l.W=WFAViVLVi\�'1F�M0l�VIQ[WlWAVAIQ 00 19321stAye., DESCRIPTION MAY 07, 2019 FIGURE Suite 201, L Seattle, WA 98101 VICINITY MAP p. 206.725.1211 I J M f. 206.973.5344 Lengineering pllc www.lpdengineering.com 0 0 U N o MAIN x Y I Y 19 ,I < I m cn E of � Q r C U U R JE - TE U ti � Y cn U U aD 0 DAYSTON ST NOHOMISH COUNTY AREA, WASHINGTON (WA661) J MAP UNIT SYMBOL MAP UNIT NAME 19 Everett very Gravelly Sandy Loam, 15 to 30% slopes U IN U AViVA\10�7■.'J»ttM1AViVAYiT Ml0�.�1��i�� 'l40V\IIIIIINDl�VI�[�]MAYi\:04 J19321stAve., DESCRIPTION MAY 07, 2019 FIGURE Suite 201, M Seattle, WA 98101 SOILS MAP p. 206.725.12112 f. 206.973.5344 engineering pllc www.lpdengineering.com Q © 2019 LPD Engineering PLLC O • W 40 1 , APPROXIMATELY 1/4 MILE '' •_;, —+-�_ DOWNSTREAM FROM SITE Q , O00, 12" SD SY ALDER ST CIO i• Q SHELLANRGER CREEK DA YTON ST MAPLE ST ALDER ST A DISCHARGE POINT FROM PROPERTY t• - _ MAIN ST r,s MAIN STREET COMMONS COMMERCIAL DEVELOPMENT 19321stAve., DESCRIPTION MAY 07, 2019 FIGURE Suite 201, Seattle, WA 98101 DOWNSTREAM p. 206.725.1211 m1m f. 206.973.5344 3 engineering pllc www.lpdengineering.com DRAINAGE MAP a a- i MAIN ST ti- ©2019 LPD Engineering PLLC EX BUILDING SITE ''IV EXISTING ACCESS DRIVEWAY EX PARKING LOT U) W Q c� X JF. ,_r As -AN 0 25 50 Scale 1 "=50' EXISTING IMPERVIOUS AREA ® Existing Impervious Total Property Area Percentage of Site Impervious 0.45 AC 0.45 AC 100% I 19321st Ave, DESCRIPTION MAY 07, 2019 FIGURE Suite 201, Seattlp.20e,W.1211 EXISTING IMPERVIOUS p. 206.725.1211 N I M f.206.973.5344 COVERAGE AND CONDITIONS 4 engineering pIIC www.lpdengineering.com W — EX BUILDING ss— ROOF TO DETENTION VAULT (BYPASS) 257 EX BUILDING ROOF TO DETENTION VAULT ©2019 LPD Engineering PLLC DISCHARGE TO EXISTING PUBLIC STORM SYSTEM AT EX CATCH BASIN DETENTION VAULT WITH FLOW CONTROL STRUCTURE M7,'IN STREET PROJECT SITE ��MAIN ST_ - .=,..P, v v v v vnt .. v ba ppl vov v„v v v vov 6 ° p ° v o, d v v 1� Iv o°'v.v°dam o, o v v v v. v. Iv ._ v v v v. _ O O Q v IO o00 o v o0 ov V p ° v. ° Ip: .. .. o ° p a. p k1k p p M vovo. qv v o ,.v o 0 0o v v 1,o v v 1, v vv o v ` v o v v o v 11 ; 4" v v o ;v o v o v v v o v o v o' v v ° - vov oov v.ov vov o00 v v: .. .° v. v �: v v�.. v o v`�: o v �: _ v v.:. v vp EY S 1� ASPHALT PARKING LOT of N X� PROPOSED BUILDING v v4. V ° i v 7 V v V v j v � v v „ v v v v: d v o v v is:`v 0 o v I v .o v 0 a v e v v ° � s i p iv e v p ° v p .Q < v. v,. CONCRETE DRIVEWAY WALKWAYS 0 15 30 Scale 1 "=30' On -Site Area Summary 3,959 SF (0.091 AC) �o PROPOSED BUILDING ROOF (NPGIS) ASPHALT/CONCRETE PAVEMENT (PGIS) 1,335 SF (0.030 AC) a%aas, p, °:a..°: CONCRETE WALKWAYS (NPGIS) 6,386 SF (0.147 AC) TOTAL NEW PLUS REPLACED EFFECTIVE IMPERVIOUS AREA 11,680 SF (0.268 AC) Off -Site Area Summar ASPHALT PAVEMENT (PGIS) 464 SF (0.011 AC) CONCRETE WALKWAYS (NPGIS) 1,582 SF (0.036 AC) TOTAL NEW PLUS REPLACED EFFECTIVE IMPERVIOUS AREA 2,046 SF (0.047 AC) FLOW CONTROL BASIN AREAS GE 93 ROOF (NPGIS) 3,959 SF (0.091 AC) Ef IE W BTM 5 ASPHALT/CONCRTE PAVEMENT (PGIS) 1,335 SF (0.030 AC) CONCRETE WALKWAYS (NPGIS) 6,386 SF (0.147 AC) NEW LANDSCAPING (NPGPS) 606 SF (0.014 AC) OFF —SITE ASPHALT PAVEMENT (PGIS) 464 SF (0.011 AC) OFF —SITE CONCRETE WALKWAYS (NPGIS) 1,582 SF (0.036 AC) 25% OF EXISTING BUILDING ROOF (NPGIS) 1,845 SF (0.042 AC) EXISTING BUILDING ROOF (PASSTHROUGH) 3,645 SF (0.084 AC) TOTAL BASIN AREA 19,822 SF (0.455 AC) 19321st Ave., DESCRIPTION February 23, 2022 FIGURE Suite 201, Seattle, PROPOSED CONDITIONS p. 206.725.1211 f.206.973.5344 TARGET SURFACES 5 engineering pIIC www.lpdengineering.com enging eerinp c /_1J»,191VA � Design Calculations and Supporting Information MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.57 Program License Number: 201410003 Project Simulation Performed on: 02/24/2022 2:37 PM Report Generation Date: 02/24/2022 2:37 PM Input File Name: Detention Sizing - East Parcel w bypass.fld Project Name: Main Street Commons Analysis Title: Detention Sizing w Pump Basin Comments: East Parcel (Existing Parking Lot) and 25% of existing building detained and 25% of existing building bypass PRECIPITATION INPUT Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 14 Full Period of Record Available used for Routing Precipitation Station : 96003605 Puget East 36 in_5min 10/01/1939-10/01/2097 Evaporation Station 961036 Puget East 36 in MAP Evaporation Scale Factor 0.750 HSPF Parameter Region Number: 3 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.455 0.455 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.455 0.455 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 4 ---------- Subbasin : Pre -Developed Site -------Area (Acres) - Till Forest 0.282 Subbasin Total 0.282 ---------- Subbasin : 25% Ex Bldg Roof -------Area (Acres) Till Forest 0.042 Subbasin Total 0.042 ---------- Subbasin: Ex Bldg Roof BYPASS -------Area (Acres) ----- Impervious 0.084 ---------------------------------------------- Subbasin Total 0.084 ---------- Subbasin : Frontage ---------- ------- Area (Acres) Till Forest 0.047 Subbasin Total 0.047 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 4 ---------- Subbasin : Developed Site --- -------Area (Acres) Till Grass 0.014 Impervious 0.268 Subbasin Total 0.282 ---------- Subbasin : 25% Ex Bldg Roof -------Area (Acres) Impervious 0.042 ---------------------------------------------- Subbasin Total 0.042 ---------- Subbasin : Ex Bldg Roof BYPASS -------Area (Acres) ----- Impervious 0.084 ---------------------------------------------- Subbasin Total 0.084 ---------- Subbasin : Frontage Bypass - -------Area (Acres) Impervious 0.047 ---------------------------------------------- Subbasin Total 0.047 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 3 Link Name: Detention Vault Link Type: Structure Downstream Link Name: PUMP Prismatic Pond Option Used Pond Floor Elevation (ft) 100.00 Riser Crest Elevation (ft) Max Pond Elevation (ft) 106.50 Storage Depth (ft) 6.00 Pond Bottom Length (ft) 50.0 Pond Bottom Width (ft) 14.0 Pond Side Slopes (ft/ft) : Z1= 0.00 Bottom Area (sq-ft) 700. Area at Riser Crest El (sq-ft) 700. (acres) 0.016 Volume at Riser Crest (cu-ft) 4,200. (ac-ft) 0.096 Area at Max Elevation (sq-ft) 700. (acres) : 0.016 Vol at Max Elevation (cu-ft) 4,550. (ac-ft) 0.104 Constant Infiltration Option Used Infiltration Rate (in/hr): 0.00 Riser Geometry Riser Structure Type : Circular Riser Diameter (in) : 6.00 Common Length (ft) : 0.000 Riser Crest Elevation : 106.00 ft Hydraulic Structure Geometry Number of Devices ---Device Number 1 --- Device Type : Circular Orifice 106.00 Z2= 0.00 Z3= 0.00 Z4= 0.00 Control Elevation (ft) 100.00 Diameter (in) 0.50 Orientation : Horizontal Elbow : No ---Device Number 2 --- Device Type Circular Orifice Control Elevation (ft) 104.75 Diameter (in) 0.75 Orientation : Vertical Elbow : Yes ---Device Number 3 --- Device Type Circular Orifice Control Elevation (ft) 105.75 Diameter (in) 1.00 Orientation : Vertical Elbow : Yes Link Name: New Copy Lnk2 Link Type: Copy Downstream Link: None Link Name: PUMP Link Type: User Rating Table Downstream Link Name: New Copy Lnk2 Elev Area Storage Discharge Infilt Discharge (ft) (ac) (ac-ft) (cfs) (cfs) 95.500 0.000 0.000 0.000 0.000 95.700 3.695 0.739 0.000 0.000 95.900 3.695 1.478 0.000 0.000 96.100 3.695 2.217 0.000 0.000 96.300 3.695 2.956 0.000 0.000 96.500 3.695 3.695 0.000 0.000 96.700 3.695 4.434 0.000 0.000 96.900 3.695 5.173 0.000 0.000 97.100 3.695 5.912 0.000 0.000 97.300 3.695 6.651 0.000 0.000 97.500 3.695 7.390 0.000 0.000 97.700 3.695 8.129 0.256 0.000 97.900 3.695 8.868 0.256 0.000 98.100 3.695 9.607 0.256 0.000 98.300 3.695 10.346 0.256 0.000 98.500 3.695 11.085 0.256 0.000 98.700 3.695 11.824 0.256 0.000 98.900 3.695 12.563 0.256 0.000 99.100 3.695 13.302 0.256 0.000 99.300 3.695 14.041 0.256 0.000 99.500 3.695 14.780 0.256 0.000 99.700 3.695 15.519 0.256 0.000 99.900 3.695 16.258 0.256 0.000 100.100 3.695 16.997 0.256 0.000 100.300 3.695 17.736 0.461 0.000 100.500 3.695 18.475 0.461 0.000 100.700 3.695 19.214 0.461 0.000 100.900 3.695 19.953 0.461 0.000 101.100 3.695 20.692 0.461 0.000 101.300 3.695 21.431 0.461 0.000 101.500 3.695 22.170 0.461 0.000 101.700 3.695 22.909 0.461 0.000 101.900 3.695 23.648 0.461 0.000 102.100 3.695 24.387 0.461 0.000 102.300 3.695 25.126 0.461 0.000 102.500 3.695 25.865 0.461 0.000 102.700 3.695 26.604 0.461 0.000 102.900 3.695 27.343 0.461 0.000 103.100 3.695 28.082 0.461 0.000 103.300 3.695 28.821 0.461 0.000 103.500 3.695 29.560 0.461 0.000 103.700 3.695 30.299 0.461 0.000 103.900 3.695 31.038 0.461 0.000 104.100 3.695 31.777 0.461 0.000 104.300 3.695 32.516 0.461 0.000 104.500 3.695 33.255 0.461 0.000 104.700 3.695 33.994 0.461 0.000 104.900 3.695 34.733 0.461 0.000 105.100 3.695 35.472 0.461 0.000 105.300 3.695 36.211 0.461 0.000 105.500 3.695 36.950 0.461 0.000 105.700 3.695 37.689 0.461 0.000 105.900 3.695 38.428 0.461 0.000 106.100 3.695 39.167 0.461 0.000 106.300 3.695 39.906 0.461 0.000 **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 4 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 4 Number of Links: 3 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perind Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Pre -Developed Site 43.099 Subbasin: 25% Ex Bldg Roof 6.465 Subbasin: Ex Bldg Roof BYPASS 0.000 Subbasin: Frontage 7.183 Link: New Copy Lnk1 0.000 Total: 56.748 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Developed Site 1.612 Subbasin: 25% Ex Bldg Roof 0.000 Subbasin: Ex Bldg Roof BYPASS 0.000 Subbasin: Frontage Bypass 0.000 Link: Detention Vault Not Computed Link: New Copy Lnk2 0.000 Link: PUMP Not Computed Total: 1.612 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.359 ac-ft/year, Post Developed: 0.010 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 ********** 2-Year Discharge Rate : 0.033 cfs 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91 % Exceedance): 0.01 cfs Off-line Design Discharge Rate (91 % Exceedance): 0.01 cfs Infiltration/Filtration Statistics -------------------- Inflow Volume (ac-ft): 56.40 Inflow Volume Including PPT-Evap (ac-ft): 56.40 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 56.40 Secondary Outflow To Downstream System (ac-ft): 0.00 Volume Lost to ET (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered+ET)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 3 ********** Link: New Copy Lnk2 ********** 2-Year Discharge Rate : 0.020 cfs 15-Minute Timestep, Water Quality Treatment Design Discharge On-line Design Discharge Rate (91 % Exceedance): 999.00 cfs Off-line Design Discharge Rate (91 % Exceedance): 999.00 cfs Infiltration/Filtration Statistics -------------------- Inflow Volume (ac-ft): 168.64 Inflow Volume Including PPT-Evap (ac-ft): 168.64 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 168.64 Secondary Outflow To Downstream System (ac-ft): 0.00 Volume Lost to ET (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered+ET)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk2 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ------------------------------------------------------------------------------------------------------------ 2-Year 3.310E-02 2-Year 1.995E-02 5-Year 4.358E-02 5-Year 2.536E-02 10-Year 5.213E-02 10-Year 2.907E-02 25-Year 6.687E-02 25-Year 3.299E-02 50-Year 8.522E-02 50-Year 4.203E-02 100-Year 9.531 E-02 100-Year 4.903E-02 200-Year 0.106 200-Year 5.325E-02 500-Year 0.120 500-Year 5.886E-02 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals **** Flow Duration Performance **** Excursion at Predeveloped 50%Q2 (Must be Less Than or Equal to 0%): Maximum Excursion from 50%Q2 to Q2 (Must be Less Than or Equal to 0%) Maximum Excursion from Q2 to Q50 (Must be less than 10%): Percent Excursion from Q2 to Q50 (Must be less than 50%): MEETS ALL FLOW DURATION DESIGN CRITERIA: PASS -73.1 % PASS -73.1 % PASS -91.9% PASS 0.0% PASS Main Street Commons Conveyance Analysis Spreadsheet 1/10/2020 Mannings Plan Total Tributary Tributary Tributary year 4trib,100-year Pipe Run Size N Slope Qfull Tributary Basins Area Impervious Area Pervious Area (MGSFIood, 15 min) GSFlo d, %Full (MGSFIood, 15 min) %Full (Inches) (h/R) (cA) (acres) (acres) (acres) (hl WI) East Parcel (Existing Parking Lot) plus Gravity Outlet Pipe from Pump Basin 6 0.012 0.006 0.47 25%of existing buidling detained plus 0.408 0.393 0.015 0.267 57% 0.409 87% existing building bypass MGS FLOOD PROJECT REPORT Program Version: MGSFlood 4.50 Program License Number: 201410003 Project Simulation Performed on: 01/14/2020 11:36 AM Report Generation Date: 01/14/2020 11:37 AM Input File Name: Conveyance Analysis - Main St.fld Project Name: Main Street Commons Analysis Title: CONVEYANCE ANALYSIS Comments: East Parcel and 25% of existing building detained and existing building bypass through vault and frontage bypass PRECIPITATION INPUT Computational Time Step (Minutes): 15 Extended Precipitation Time Series Selected Climatic Region Number: 14 Full Period of Record Available used for Routing Precipitation Station : 96003605 Puget East 36 in_5min 10/01/1939-10/01/2097 Evaporation Station 961036 Puget East 36 in MAP Evaporation Scale Factor 0.750 HSPF Parameter Region Number: 1 HSPF Parameter Region Name : USGS Default ********** Default HSPF Parameters Used (Not Modified by User) *************** ********************** WATERSHED DEFINITION *********************** Predevelopment/Post Development Tributary Area Summary Predeveloped Post Developed Total Subbasin Area (acres) 0.408 0.408 Area of Links that Include Precip/Evap (acres) 0.000 0.000 Total (acres) 0.408 0.408 ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 3 ---------- Subbasin : Pre -Developed Site -------Area (Acres) - Till Forest 0.282 Subbasin Total 0.282 ---------- Subbasin : 25% Ex Bldg Roof -------Area (Acres) Till Forest 0.042 Subbasin Total 0.042 ---------- Subbasin : Ex Bldg Roof BYPASS -------Area (Acres) ----- Impervious 0.084 ---------------------------------------------- Subbasin Total 0.084 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 3 ---------- Subbasin : Developed Site --- -------Area (Acres) Till Grass 0.015 Impervious 0.267 Subbasin Total 0.282 ---------- Subbasin : 25% Ex Bldg Roof -------Area (Acres) Impervious 0.042 ---------------------------------------------- Subbasin Total 0.042 ---------- Subbasin : Ex Bldg Roof BYPASS -------Area (Acres) ----- Impervious 0.084 ---------------------------------------------- Subbasin Total 0.084 ************************* LINK DATA ******************************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None ************************* LINK DATA ******************************* ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 Link Name: New Copy Lnk1 Link Type: Copy Downstream Link: None **********************FLOOD FREQUENCY AND DURATION STATISTICS******************* ----------------------SCENARIO: PREDEVELOPED Number of Subbasins: 3 Number of Links: 1 ----------------------SCENARIO: POSTDEVELOPED Number of Subbasins: 3 Number of Links: 1 ***********Groundwater Recharge Summary ************* Recharge is computed as input to Perind Groundwater Plus Infiltration in Structures Total Predeveloped Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Pre -Developed Site 43.099 Subbasin: 25% Ex Bldg Roof 6.465 Subbasin: Ex Bldg Roof BYPASS 0.000 Link: New Copy Lnk1 0.000 Total: 49.564 Total Post Developed Recharge During Simulation Model Element Recharge Amount (ac-ft) Subbasin: Developed Site 1.727 Subbasin: 25% Ex Bldg Roof 0.000 Subbasin: Ex Bldg Roof BYPASS 0.000 Link: New Copy Lnk1 0.000 Total: 1.727 Total Predevelopment Recharge is Greater than Post Developed Average Recharge Per Year, (Number of Years= 158) Predeveloped: 0.314 ac-ft/year, Post Developed: 0.011 ac-ft/year ***********Water Quality Facility Data ************* ----------------------SCENARIO: PREDEVELOPED Number of Links: 1 ********** Link: New Copy Lnk1 Infiltration/Filtration Statistics -------------------- Inflow Volume (ac-ft): 53.44 Inflow Volume Including PPT-Evap (ac-ft): 53.44 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 53.44 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ----------------------SCENARIO: POSTDEVELOPED Number of Links: 1 Link: New Copy Lnk1 Infiltration/Filtration Statistics -------------------- Inflow Volume (ac-ft): 157.27 Inflow Volume Including PPT-Evap (ac-ft): 157.27 Total Runoff Infiltrated (ac-ft): 0.00, 0.00% Total Runoff Filtered (ac-ft): 0.00, 0.00% Primary Outflow To Downstream System (ac-ft): 157.27 Secondary Outflow To Downstream System (ac-ft): 0.00 Percent Treated (Infiltrated+Filtered)/Total Volume: 0.00% ***********Compliance Point Results ************* Scenario Predeveloped Compliance Link: New Copy Lnk1 Scenario Postdeveloped Compliance Link: New Copy Lnk1 *** Point of Compliance Flow Frequency Data *** Recurrence Interval Computed Using Gringorten Plotting Position Predevelopment Runoff Postdevelopment Runoff Tr (Years) Discharge (cfs) Tr (Years) Discharge (cfs) ------------------------------------------------------------------------------------------------------------ 2-Year 3.261 E-02 2-Year 0.141 5-Year 4.305E-02 5-Year 0.186 10-Year 5.148E-02 10-Year 0.220 25-Year 6.621 E-02 25-Year 0.267 50-Year 8.477E-02 50-Year 0.339 100-Year 9.523E-02 100-Year 0.409 200-Year 0.102 200-Year 0.438 500-Year 0.110 500-Year 0.477 ** Record too Short to Compute Peak Discharge for These Recurrence Intervals Page of T LPD Staff- Date: Name: Company: Phone: Proj. Name: Subject: -7 Phone Log 7IMerno DMeeting Notes FISite Visit Notes 7IDesign / Calculation By: 1932 First Avenue, Suite 201 Phone: 206.725.12 1 1 Seattle, WA 98101 www.lpdengineering.com TECHNICAL BROCHURE B3887BHF R3 FEATURES Impeller: Cast iron, enclosed, non -clog, dynamically balanced with pump outvanes For mechanical seal protection. Casing- Cast Iron flanged volute type for maximum efficiency. Designed for easy Installation on Al0-20 slide rail or base elbow rail systems, Mechanical Seal: SILICON CARBIDE VS. SILICON CARBIDE sealing faces for superior abrasive resistance, stainless steel metal parts, BONA-N elastbmers, Shaft: Corrosion -resistant, 300 series stainless steel. Threaded design, Locknut on all models to guard against component damage on accidental reverse rotation. Fasteners: 300 series stainless steel. Capable of running dry without damage to components. Designed for continuous operation when fully submerged. EXTENDED WARRANTY AVAILABLE FOR RESIDENTIALAPPLICAfIONS. WS-- ry ' F S Mudef-m3£i�t7LH1= SlJD,'AEi;::IBLE S ':`i,��l r't,r.Vi:' I r OWLDS `tr' A."T:RITE. f0 tii..O Y a xylem brand Wastewater s + APPLICATIONS Spec!fic2lly designed forthe following uses: * Homes • Watertransfer ® Sewage systems - Light industrial a Dewatering/Effluent o Commercial applications Anywhere waste or drainage must be disposed of quickly, quietly and efficiently. SPECIFICATIONS Pump o Solids handling capabilities: 2" makimum • Capacihes: up to 220 GPM Total heads: up to 81 feetTDH Discharge size: 2" NPTthreaded companion -flange as standard. 3" option available but must be ordered separately, (Order no. Al-3) lemper4l.ire: 104°F (40°C) continuous 140°F (60°C) intermittent, MOT017w Fully submerged in high grade turbine oil for lubrica- tion and efficient heat transfer. All ratings are within the working limits of the motor. Class B insulation on'IA-1'A HP models. Class F insulation on 2 HP models. METERS FEET 30 r lOJ �I U a z M H 25 60 70 21) r,a Singe phase (60 Hx): r Capacitor -start motorsformaximum start!ngtorque. �+ Built-in overload with automatic reset. o SJTOW or STOW severe duty oil and water resistant power cords, ++ h-1 HP models have NEMAthree prong ground- ing plugs. n 11/7. HP and larger units have bare lead cord ends. Three phase C60 Hz)! b Class 10 overload protection must be provided in separately ordered starter unit. +' STOW power cords all have bare lead cord ends. Bearings: Upper and lower heavy duty ball bearing construction. Designed for Continuous Operation: Pump ratings are within the motor manufacturer's recommended working limits, can be operated continuously without damage when fully submerged, c Power Cable: Severe duty rated, oil and water resistant. Epoxy sea! on motor end provides secondary moisture barrier in case of outer jacket damage and to prevent oil wicking. Standard cord is 20'. Optional lengths are available. Motor Cover O-ring: Assures positive sealing against contaminants and oil leakage. AG.FNCY LISTINGS Tested to UL778 and CSA 22.2 108 Standards By Canadian Standards Association c us File#LR38549 L�! . ,__ _ i' r•.l T...I._ .._' i. Y _. r __� ��_ I ! SERIES: WS_BHF DISCHARGE:2rr 2" —) 6--i0 GPM —I..._; _-�_ ! _ ; --{---- _ I T i i SOLIDS: RPM:3500 i 7•—•, t I FT 11 I it i4 I L.. i i- t _211)1�p 1. 26• 40 60 80 100 120 140 160 160 200 220 240 U.S, GPM \ u 10 20 J0 40 s0 tY13/h PAGE: F1.0 V RATE_ MgTOR AND MODEL INFORMATION order Number HP phase - Volts I RPM Impeller Diameter (in.) [vSaximum Amps Locked Rotor Amps [NA code Full Load tVlotor Efficiency Resistance Start Line -Line WS0311 BHFT230 0.33 208-i I 230 200 1 3 �2 0 ; -160 i I I ^575J 2.94 12.4 46.0 M 54 7.5 1.0 W5031 BBHF 6.8 31.0 K 68 9.7 2.4 WS0312BFIF 6,2 34.5 M 53 9,6 4.0 W50511BHF 0.5 j 3.19 14.5 46.0 M 54 7,S 1.0 W5051SBHF 8A 31.0 K 6B / 9.7 2.4 W505128HF 7.6 34.5 M 53 9.6 4.0 WS0538BHF WS0532BH 4.9 1 22.6 R 68 - 3.8 �_ 3.6 i B,B R 70 - S.B WS0534BHF j WS05378HF 1.8 j_ 9.4 R 7d - 23.2 1.5 7.5 R 62 - 35.3 WS071 BDriF ) ) 1 208 WS0712BHF 1 230 W507368HF j GOOJ WS0732BH0.75 ( .3 230 i F WS0734Bif460_I VV50737BHF l 1 575 i W51018BHF 1 G0fi _ 3500 WS1012BHF a i 1 --- ;-= W510388_11; ! 1 200 WS10326r!F { 1 i 230 ; W51034BHF 3 1 46D W51037SHF I 575 3.445A 11.0 31.0 K 68 9.7 2.4 10.0 27.5 J 65 12.2 2.7 6,2 20.6 L • 64 - 5.7 15.7 K 68 6.6 2.7 22� 7.9 9.9 K ( L 68 78 - 11 26.5 _ 14.5 _59.0 13.0 36.L 8.6 . I 27.6 3.75 75 211.1 3.8 12.1 3.1 9.9 K 68 9.3 1.1 1 J 69 10.3 2.1 ; M 77 - 2.7 L 79 - 4.1 L 79 - 16.2 L 78 - 26,5 WS1512BHF 1 23D 200� 1.5 3 ) 230 460 ;; F 57ti J 230 1, i ; 200 2 3 2:t0 , ' 460 i 575 I 4.00 18.0 S2.0' J 67 2.76 O.S3 1N515386HF 10.0 42.4 K 7B - 1.7 W51532DHc� 9,6 4.8 < 78 - 1.7 WSI534BH, 21.2 K 78 - 6.6 W51537DHF WS2012ohF I 3.11 16,3 L 78 - 10.5 4.44r�5.8 i 8.0 09.6 F 78 3,2 1.1 W521}38DH=' 2.0 42.4 K 78 - '1.7 WS20320HF .6 42.4 K 78 - 1.7 I/JS2034RHF 21.2. K 78 - 6.6 WS20316HF1 1.7 16.3 L 78 - 10.5 DIMENSIONS (All dimensions are in inches. Do no-, use for construction purposes.) 12yz`---__- I Discharge Flange ( �1 1 bye, 7 c. Discharge Flange: (D 2" NPTstandard n 0 rJ 3" NPT optional.(order an Al-3) PAGE 3 engingOpiceerin APPENDIX C Construction Stormwater Pollution Prevention Plan (SWPPP) Narrative Main Street Commons Commercial Development I M Construction SWPPP Narrative May 1, 2019 engineering Pic MAIN STREET COMMONS COMMERCIAL DEVELOPMENT CONSTRUCTION SWPPP NARRATIVE MAY 7v 2019 The following Construction Storm Water Pollution Prevention Plan (SWPPP) narrative is for Main Street Commons Commercial Development Project. The site is located at 550 Main St in Edmonds, Washington. The narrative supplements the Temporary Erosion and Sediment Control (TESC) plan. This narrative and the drawings address the requirements of Volume II of the Department of Ecology (DOE) 2012 Stormwater Management Manual for Western Washington (SMMWW), amended in 2014. Refer to the TESC plans (Sheets C1.0) and TESC details (Sheets C 1.1) for more information regarding any erosion or sedimentation control measures involved in this project. 1. CONSTRUCTION STORMWATER POLLUTION PREVENTION ELEMENTS 1) Mark Clearing Limits: Clearing limits will be delineated on the TESC and Site Demolition plan. The actual limits of clearing will likely be smaller than the limit of work, but this identifies the maximum extent of the clearing limits. Areas impacted and not anticipated to be covered with final measures shall be stabilized using approved permanent TESC methods. 2) Establish Construction Access: Construction access will be provided at the existing southeast access driveway, with temporary quarry spall construction entrance (BMP C 105) as necessary. The Contractor shall provide wheel wash if necessary. 3) Control Flow Rates: Stormwater flow control during construction will be mitigated by routing runoff to a 4,000-gallon temporary sediment storage facility. Refer to the Sediment Tank Sizing calculations and the associated MGS Flood output included within Appendix B of the project's Stormwater Site Plan. Permanent flow control facilities include a detention vault that will be located on the northwest side of the property. 4) Install Sediment Controls: DOE approved BMPs for sediment controls are shown on the TESC plan. Sediment will be controlled using silt fence (BMP C233) and storm drain inlet protection (BMP C220). 5) Stabilize Soils: It is possible that some of the earthwork and grading may occur in wet weather conditions. The site must be stabilized and no soils will be allowed to remain unstabilized for more than two days between October 1st and April 30th. From May 1 through September 30, install cover measures to protect disturbed areas that will remain unworked for seven days or more. By October 8, seed all areas that will remain unworked from October 1 through April 30. Mulch all seeded areas. Exposed slopes will be protected by DOE -approved coverage methods. BMPs including, but not limited to: C 101, Preserving Natural Vegetation; C 121, Mulching; C 123, Plastic Covering; C 130, Surface Roughening; C 140, Dust Control; and T5.13 Post Construction Soil Amendment will be used to stabilize on -site soils during construction. 6) Protect Slopes: The DOE -approved BMPs for slope protection will be utilized during construction. Concentrated discharges shall not be allowed to flow over the top of steep Page I Main Street Commons Commercial Development I M Construction SWPPP Narrative May 1, 2019 engineering Pic slopes. BMPs including, but not limited to C101, Preserving Natural Vegetation; C121, Mulching; C123, Plastic Covering; C130, Surface Roughening; C140, Dust Control; C208, Triangular Silt Dike; C207, Check Dams; and C233, Silt Fence are to be utilized to protect slopes during construction. 7) Protect Drain Inlets: Drainage structures in areas where no work occurs will remain and will be protected; discharge points to the public storm drain main line will also be protected. To prevent discharge of turbid water downstream, all existing catch basins located within the disturbance area and outside of the disturbance area within approximately 300 feet downstream of the site will be protected with storm drain inlet protection (BMP C220). The Contractor shall remove inlet protection at the end of the project without releasing captured sediment into the storm system. 8) Stabilize Channels and Outlets: DOE -approved BMPs for channel stabilization will be utilized during construction, including, but not limited to: C200, Interceptor Dike and Swale; and C207, Check Dams. 9) Control Pollutants: Temporary protection of the disturbed soils provides the first level of protection for pollution control, and perimeter measures downstream will mitigate the remaining pollutants. The temporary protection of disturbed soils may be mitigated with a temporary sump and pump facility to provide the second level of interception of pollutants. This collection system filters sediments prior to the pump system. The pump system will then route stormwater via force mains into the temporary sediment settling facility. Construction debris will be removed from the site. The Contractor will be responsible for managing their construction equipment per DOE -approved BMPs. If a truck wheel wash is required, truck wheel wash water and concrete truck washout water shall be collected and discharged to the public sanitary sewer (SS) system. To apply for and obtain a SS release, contact the local sewer purveyors for authorization. 10) Control De -Watering: the event that perched groundwater is encountered during any wet season construction, the Contractor shall route it to the sediment settling facility by pumping it out of the excavation. 11) Maintain BMPs: DOE -approved standard BMP maintenance will be required in accordance with the City of Edmonds standard TESC plan notes (Sheet C0.5). 12) Manage the Project: All phases of construction will be managed by the Contractor. The site must be stabilized and no soils will be allowed to remain exposed and unworked for more than two days between October 1st and April 30th and for more than seven days between May Pt and September 30th. The Contractor will provide maintenance and monitoring of TESC BMPs. Work of all contractors will be coordinated to minimize the duration of disturbance on the site. The best management practices shown on the TESC plan are minimum requirements. Failure to maintain SWPPP measures in accordance with adopted standards may result in the work being performed at the City's direction and the costs assessed as a lien against the property where such facilities are located. 13) Protect Low -Impact Development BMPs: The project proposes compost amended soil for new landscape areas as a Low -Impact Development BMP. Page 2 Main Street Commons Commercial Development Construction SWPPP Narrative May 1, 2019 enging eerinp c 2. PROJECT DESCRIPTION The proposed project includes the renovation of the existing on -site building and construction of a new two-story commercial building. Additionally, parking for the entire commercial development, named Main Street Commons, will sit adjacent to the south of the newly constructed building and south of the courtyard area proposed as a part of the renovation of the existing building. The project proposes 11,585 square feet (0.080 acres) of new plus replaced hard surface. The total project disturbance is 13,195 square feet (0.303 acres). Flow control will be addressed with detention vault located northwest between the existing and proposed buildings. A flow control structure will be located on the discharge point from the detention facility. Water quality will not be provided since the project proposes less than 5,000 square feet of pollution generating impervious surfaces. Refer to the project's stormwater site plan for more information. Estimated earthwork quantities for the project include approximately 425 cubic yards of cut and fill, 20 cubic yards of asphalt paving, 200 cubic yards of concrete paving and base. There will be approximately 4,500 CY of export for excavation for the detention vault. These quantities are estimates only and intended for municipal permitting. These quantities shall not be used by the Contractor as a basis for any contractual information. The Contractor shall prepare their own earthwork quantities based upon the information provided in the contract documents. 3. EXISTING SITE CONDITIONS The project is located on two parcels (#00434212001700 and #00434212001500), with an area of approximately 0.45-acres (19, 602 sf). The corner parcel is approximately 0.30-acres (13,068 sf) and the westerly parcel is approximately 0.15-acres (6,534 sf). The site currently consists of a surface parking lot encompassing the east portion of the site and an approximately 6,900 sf commercial building on the west. The topography of the corner parcel, currently developed with a surface parking lot, slopes to the west from a high elevation point of approximately 92-feet to a low point of 86-feet. The existing building on the parcel adjacent to the west has a zero -lot line, and thus, topographically, the parcel is fully developed and relatively flat. According to maps of the City's drainage basins, the site is located in the Shellabarger watershed. Stormwater runoff from the parking lot sheet flows to the west draining to storm inlets and an associated on -site private drainage line that conveys flow northerly towards the public system in Main Street. Within the public system, stormwater is conveyed further west, then south eventually discharging into Shellabarger Creek, which flows into Edmonds Marsh ultimately outfalling into the Puget Sound. 4. ADJACENTAREAS The property is bounded by 6th Avenue S to the east, Main Street to the north, an alley to the south, and a commercial/retail structure to the west. Vehicular access to the site is from the north-east off 6th Ave S, and from the southeast off 6th Ave S. Page 3 Main Street Commons Commercial Development Construction SWPPP Narrative May 1, 2019 enging eerinp c S. CRITICAL AREAS Based on City of Edmonds mapping, there are no environmentally critical areas within the project area. 6. SOILS A geotechnical report was prepared by PanGeo, dated November 4, 2018. Their subsurface exploration observed existing generally dense fill up to 4 feet thick overlying medium dense to dense native soils consisting of medium dense to very dense, silty fine to medium sand with gravel and very dense, silty fine sand with pebble -sized gravels. According to the geotechnical report the silty fine to medium sand with gravel appeared consistent with mapped Transitional Beds at the site and the silty fine sand with pebble -sized gravels appeared consistent with Olympia Gravel mapped in the are just north of the site. 7. POTENTIAL EROSION PROBLEM AREAS There are no anticipated potential erosion problems within or adjacent to the project area. H. CONSTRUCTION PHASING The contractor is responsible for coordinating work of all subcontractors to keep the duration of site disturbance limited to the maximum extent possible. 9. CONSTRUCTION SCHEDULE Construction of this Project is expected to begin in Summer of 2019 and be completed in 2020. Should any wet weather conditions occur during construction, the contractor shall implement the de -watering procedures outlined in this SWPPP and applicable BMPs including, but not limited to C123, Plastic Covering; C121, Mulching; C122, Nets and Blankets; C126, Polyacrylamide for Soil Erosion Protection; C130, Surface Roughening. 10. FINANCIAL/OWNERSHIP RESPONSIBILITIES A bond quantity worksheet has been prepared for the project. The property owner will be responsible for posting a performance and payment bond with the City and will be the responsible party for any liability associated with erosion and sedimentation impact. 11. ENGINEERING CALCULATIONS A copy of any calculations performed during design of the project and relevant storm drainage modeling discussions is included in the project's Stormwater Site Plan. Page 4 enging eerinp c /_\J»,2191VA � Geotechnical Report PanGEO I N C O R P O R A T E D Geotechnical & Earthquake Engineering Consultants November 14, 2018 Project No. 18-358 Michael McMurray Seattle -Snohomish Mill Company, Inc. 533 5th Avenue South Edmonds, WA 98020 Subject: Geotechnical Report Proposed Development 550 Main Street, Edmonds, Washington Dear Mr. McMurray, Attached please find our geotechnical report for your proposed project. In summary, our test borings completed at the site encountered about 4 feet of generally dense fill overlying medium dense to dense native soils. In our opinion, conventional footings and concrete slab -on -grade floors are feasible to support the proposed new building and as well as the renovation of the existing building. The proposal art panels and signs may be supported on conventional footings or piles, depending on the magnitude of uplift forces. In our opinion, if practical, conventional footings should be used in lieu of piles/shafts as footing construction generally has less construction uncertainties than piles, and likely more economical than piles. We appreciate the opportunity to work on this project. Please call if there are any questions. Sincerely, Slew L. Tan, P.E. Principal Geotechnical Engineer Encl.: Geotechnical Report 3213 Eastlake Avenue East, Suite B Seattle, WA 98102 Tel (206) 262-0370 Fax (206) 262-0374 TABLE OF CONTENTS 1.0 INTRODUCTION................................................................................................................... 1 2.0 PROJECT AND SITE DESCRIPTION............................................................................... I 3.0 SUBSURFACE EXPLORATIONS....................................................................................... 2 4.0 SUBSURFACE CONDITIONS............................................................................................. 2 4.1 SOIL....................................................................................................................................... 2 4.2 GROUNDWATER..................................................................................................................... 3 5.0 GEOTECHNICAL RECOMMENDATIONS..................................................................... 4 5.1 SEISMIC DESIGN PARAMETERS............................................................................................... 4 5.2 FOUNDATION.......................................................................................................................... 4 5.2.1 Building Foundation...................................................................................................... 4 5.2.2 Foundation for Art Panels and Signs............................................................................. 6 5.3 RETAINING WALL DESIGN PARAMETERS............................................................................... 6 5.4 CONCRETE SLAB ON GRADE.................................................................................................. 8 5.5 PERMANENT DRAINAGE CONSIDERATIONS............................................................................ 8 5.6 PERMANENT SLOPES.............................................................................................................. 8 6.0 CONSTRUCTION CONSIDERATIONS............................................................................ 9 6.1 FOOTING SUBGRADE.............................................................................................................. 9 6.2 TEMPORARY EXCAVATION AND DEWATERING...................................................................... 9 6.3 STRUCTURAL FILL AND COMPACTION.................................................................................... 9 6.4 EROSION AND DRAINAGE CONSIDERATIONS........................................................................ 10 6.5 WET EARTHWORK RECOMMENDATIONS.............................................................................. 10 6.6 INFILTRATION CONSIDERATIONS.......................................................................................... 11 7.0 LIMITATIONS..................................................................................................................... 11 8.0 REFERENCES...................................................................................................................... 14 LIST OF ATTACHMENTS Figure 1 Vicinity Map Figure 2 Site and Exploration Plan Appendix A Summary Boring Logs Figure A-1 Terms and Symbols for Boring an Test Pit Logs Figure A-2 Log of Test Boring PG-1 Figure A-3 Log of Test Boring PG-2 Figure A-4 Log of Test Boring PG-3 Figure A-5 Log of Test Boring PG-4 GEOTECHNICAL REPORT MAIN STREET COMMONS 550 MAIN STREET, EDMONDS, WASHINGTON 1.0 INTRODUCTION This report presents the results of our geotechnical studies that were undertaken to support the design and construction of the proposed project. We performed our geotechnical evaluations in general accordance with the scope of work outlined in our proposal dated October 23, 2018, which was subsequently approved by you on October 24, 2018. Our service scope included reviewing readily available geologic data, conducting a site reconnaissance, drilling four test borings at the site, and developing the conclusions and recommendations presented in this report. 2.0 PROJECT AND SITE DESCRIPTION The site consists of two parcels at 550 Main Street of Edmonds, Washington. The site is bordered to the north by Main Street, east by 6th Avenue South, south by an improved alley, and to the west by a mixed -use building. The site is currently occupied to the west by a commercial building, which will be remodeled during this project, and to the east by an asphalt parking lot to be removed for the additional proposed structures. The existing building has a partial basement that extends about 8 to 9 feet below the existing site grade. Based on the project topographic survey, the existing site grade descends gently from the east to the west property line, with a total elevation relief of about 8 feet, over a length of about 180 feet. A current view of the site is shown in Plate 1, at right. We understand that the existing arch - roofed building will be remodeled, and a new building will be constructed at the parking lot located immediately east of the existing building, in the northeast quadrant of Plate 1: Current view of 550 Main Street; looking northwest (1110712018) Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 the site. We also understand that three billboard type structures for art panels will be constructed at the property. 3.0 SUBSURFACE EXPLORATIONS Four test borings (borings PG-1 thru PG-4) were completed at the site on November 7, 2018. The approximate boring locations are shown on Figure 2. Boring PG-1 was drilled to a depth of about 21 feet, while PG-2, PG-3, and PG-4 were drilled to a depth of 11 %2 feet. These borings were progressed using a EC95 track -mounted drill rig owned and operated by Boretec, Inc. The drill rig was equipped with a 6-inch outside diameter hollow stem auger, and soil samples were obtained from the borings at 2'/2- and 5-foot depth intervals in general accordance with Standard Penetration Test (SPT) sampling methods (ASTM test method D-1586) in which the samples are obtained using a 2-inch outside diameter split -spoon sampler. The sampler was driven into the soil a distance of 18 inches below the tip of the auger using a 140-pound weight falling a distance of 30 inches. The number of blows required for each 6-inch increment of sampler penetration was recorded. The number of blows required to achieve the last 12 inches of sample penetration is defined as the SPT N-value. The N-value provides an empirical measure of the relative density of cohesionless soil, or the relative consistency of fine-grained soils. A geologist from PanGEO was present throughout the field exploration program to observe the drilling, assist in sampling, and to document the soil samples obtained from the borings. The completed borings were backfilled with bentonite chips and patched with asphalt. The soil samples retrieved from the borings were described using the system outlined on Figure A-1 of Appendix A and the summary boring logs are included as Figures A-2 and A-5. 4.0 SUBSURFACE CONDITIONS 4.1 SOIL According to the Geologic Map of the Edmonds East Quadrangle (Minard, 1983), the project site is underlain by Transitional Beds (Qtb) with Olympia Gravel (Qog) mapped to the north of the site. Transitional Beds are described as glacial and non -glacial deposits typically composed of both thick and thin beds of fine clay silt and sand particles, with gravel near to the base of the formation. These beds typically have a high water content. Olympia Gravel is described as a weakly cemented fluvial sand with pebble sized gravels. 18-358 550 main street, edmonds 2 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 Based on our interpretation of the soil samples from the test borings, it appears that the site soil conditions are consistent with the mapped geology, with Transitional Beds overlying Olympia Gravel. A description of the generalized soil units encountered in our test borings is presented below: Asphalt — All 4 test borings were drilled through the existing parking lot pavement, and encountered 4 to 8 inches of asphalt. Soil Unit 1: Fill — Directly below the asphalt, the test borings encountered approximately 4 feet of fill. The fill generally consisted of a medium dense to dense, moist, grey to brown, slightly silty fine to medium sand with gravels. Based on the SPT N-values recorded in the test borings, the site fill appeared generally well compacted. Soil Unit 2: Transitional Beds (Qtn) — Below the fill, a medium dense to very dense, moist to wet layer of brown to grey silty fine to medium sand with gravel was encountered. Evidence of iron -oxide staining and perched groundwater was present throughout this unit. Borings PG-2, PG-3, and PG-4 were terminated in this unit. In boring PG-1 this unit ended at about 16 1/2 feet below ground surface. This unit appears consistent with the mapped Transitional Beds at the site. Soil Unit 3: Olympia Gravel (Qog) — Below the Transitional Beds in PG-1, a very dense, blue -grey, silty fine sand with pebble -sized gravels was encountered and extended to the maximum depth of the boring. This soil unit appears consistent with the Olympia Gravel mapped in the area just north of the site. 4.2 GROUNDWATER Perched groundwater seepage and evidence of iron -oxide staining was commonly present within the Transitional Beds of the test borings during drilling. In PG -I, at a depth of 20 feet, groundwater was reached and subsequently filled the boring with water to approximately 91/2 feet below ground surface. It should be noted that groundwater elevations are likely to vary depending on the season, local subsurface conditions, and other factors. Groundwater levels are normally highest during the winter and early spring. Presence of perched water at the fill contact is common during wet winter -spring months. 18-358 550 main street, edmonds 3 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 5.0 GEOTECHNICAL RECOMMENDATIONS 5.1 SEISMIC DESIGN PARAMETERS The following provides seismic design parameters for the site that are in conformance with the 2015 International Building Code (IBC), which specifies a design earthquake having a 2% probability of occurrence in 50 years (return interval of 2,475 years), and the 2008 USGS seismic hazard maps. It is our opinion that Site Class D is appropriate for this project. 5.2 FOUNDATION 5.2.1 Building Foundation Based on the site subsurface condition encountered in our test borings, it is our opinion that conventional footings can be utilized for the proposed building renovation and the new building. The footings may be founded on the existing site fill, provided that the fill at the footing locations are well compacted, or on the undisturbed native soils below the fill. We recommend that the adequacy of all footing bearing surface be verified by PanGEO before placing reinforcing steel and formwork. Any loose soils should be completely removed from the footing excavations and replaced with properly compacted structural fill. Allowable Bearing Pressure — In our opinion, for footings placed on the suitable bearing soils or properly compacted structural fill as discussed above, the footings may be sized using a maximum allowable bearing pressure of 4,000 psf. For allowable stress design, the recommended allowable bearing pressure may be increased by 1/3 for transient conditions such as wind and seismic loadings. Spread and continuous footings should have minimum widths of 24 and 18 inches, respectively. Lateral Resistance — Lateral forces from wind or seismic loading may be resisted by a combination of passive earth pressures acting against the embedded portions of the foundations and walls, and by friction acting on the base of the foundations. Passive resistance values may be determined using an equivalent fluid weight of 300 pounds per cubic foot (pcf) for level backfill. This value includes a factor safety of at least 1.5 assuming that properly compacted structural fill will be placed adjacent to the sides of the footings. A friction coefficient of 0.35 may be used to determine the frictional resistance at the base of the footings. This coefficient includes a factor of safety of approximate 1.5. 18-358 550 main street, edmonds 4 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 Foundation Performance — Total and differential settlements are anticipated to be within tolerable limits for footings designed and constructed as discussed above. Footing settlement under static loading conditions is estimated to be less than approximately 1 inch, and differential settlement between adjacent columns should be less than about '/2 inch. Most settlement will occur during construction as loads are applied. Our observations of the existing building performance indicate that localized footing settlement had occurred near the southeast corner of existing building (see rotated door frame in Plate 2, below). It is probable that a portion of the existing footings was constructed on loose soils. Depending on the final foundation design of the proposed building renovation, it may be necessary to locally retrofit the existing footings. Plate 2. Footing settlement resulted in twisted door frame and cracks in wall. SE corner of building, looking north. 18-358 550 main street, edmonds 5 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 5.2.2 Foundation for Art Panels and Signs We understand that art panels and signs will be installed. The loading conditions on its foundation are not available at this time, but we understand that the foundation may be subjected to uplifts. It is our opinion that, if the uplift forces are not significant, and can be addressed with the mass of concrete footings, it is our opinion that footings should be used in lieu of piles. The recommendations outlined in Section 5.2.1 are also applicable for footings supporting the art panels and signs. However, if the uplift forces are significant and piles are needed, we recommend using cast -in - place concrete piles, such as augercast piles or drilled shafts. For design purposes, we recommend that an allowable skin friction of 1 ksf be used to size the augercast piles or drilled shafts, assuming the piles/shafts are at least 15 feet deep. An allowable end bearing of 20 ksf may also be used for piles/shafts in compression loads. Lateral forces from wind or seismic loading may be resisted by a combination of passive earth pressures acting against the embedded portions of the pile cap, and by the structural stiffness of the piles. If needed, PanGEO is available to perform a laterally -load pile analysis, based on the geometry and loading conditions provided by the structural engineer. 5.3 RETAINING WALL DESIGN PARAMETERS Presented below are our geotechnical recommendations for the design and construction of retaining walls. Lateral Earth Pressure — Cantilevered walls should be designed for an equivalent fluid pressure of 35 pcf for level backfills behind the walls assuming the walls are free to rotate. If walls are to be restrained at the top from free movement, such as basement walls, equivalent fluid pressures of 45 pcf should be used for level backfills behind the walls. Permanent walls should be designed for an additional uniform lateral pressure of 7H psf for seismic loading, where H corresponds to the buried depth of the wall. The recommended lateral pressures assume that the backfill behind the wall consists of a free draining and properly compacted fill with adequate drainage provisions. Wall Surcharge — Surcharge loads, where present, should also be included in the design of retaining walls. We recommend that a lateral load coefficient of 0.35 be used to compute 18-358 550 main street, edmonds 6 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 the lateral pressure on the wall face resulting from surcharge loads located within the height dimension of the wall. Lateral Resistance — Lateral forces from wind or seismic loading and unbalanced lateral earth pressures may be resisted by a combination of passive earth pressures acting against the embedded portions of the foundations and by friction acting on the base of the foundations. Passive resistance values may be determined using an equivalent fluid weight of 300 pounds per cubic foot (pcf) for level backfill. A friction coefficient of 0.30 may be used to determine the frictional resistance at the base of footings. Both values include a safety factor of at least 1.5. Wall/Foundation Drainage — We recommend that perimeter wall/footing drains be installed to prevent a buildup hydrostatic pressure behind walls. As a minimum, 4-inch diameter perforated drainpipes should be installed next to the base of the footings and embedded in 12 to 18 inches of pea or washed gravel. The gravel should be wrapped in a geotextile filter fabric to prevent the migration of fines into the drain system. The drainpipe should be graded to direct water to a suitable outlet and should not be allowed to daylight over the slope. If the proposed basement wall will be constructed against the temporary shoring wall (soldier pile wall with timber lagging), prefabricated drainage mats, such as Mirafi 6000 or equivalent, may be installed behind the basement walls and the collected water should be directed to a 4-inch diameter perforated collector pipe located along the inside perimeter of wall footing and discharged to an appropriate outlet. Wall Backfill — Wall backfill, if needed, should consist of free draining granular soils. In our opinion, the native excavated soils consist of a high fines content, and are not suitable to be re -used as wall backfill. Imported wall backfill such as City of Seattle Type 17 Mineral Aggregates (Section 9.03.10 (1) of the 2017 Seattle Standard Specifications) or Gravel Borrow (Section 9.03.14 (1) of the 2018 WSDOT Standard Specifications) should be assumed for this project. The structural fill should be moisture conditioned to near its optimum moisture content, placed in loose, horizontal lifts less than 8 to 12 inches in thickness, and systematically compacted to a dense and relatively unyielding condition. The adequacy of the compaction should be verified by PanGEO. If density tests will be performed, the test results should 18-358 550 main street, edmonds 7 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 indicate at least 95 percent of the maximum dry density, as determined using test method ASTM D 1557. Within 5 feet of the wall, the backfill should be compacted to 90 percent of the maximum dry density. Damp Proofing — Waterproofing considerations are beyond our scope of work. We recommend that a building envelope specialist be consulted to determine appropriate damp - proofing or water -proofing measures. 5.4 CONCRETE SLAB ON GRADE Conventional on -grade concrete slabs may be utilized for this project. The slab may be constructed on densely compacted fill, or undisturbed native soils. Interior concrete slab -on - grade floors should be underlain by a capillary break consisting of at least of 4 inches of compacted 3/4-inch, clean crushed rock (less than 3 percent fines). The capillary break material should also have no more than 10 percent passing the No. 4 sieve and less than 5 percent by weight of the material passing the U.S. Standard No. 100 sieve. The capillary break should be placed on the dense subgrade or subgrade that has been compacted to a dense and unyielding condition. A I0-mil polyethylene vapor barrier should also be placed directly below the interior slab. 5.5 PERMANENT DRAINAGE CONSIDERATIONS Permanent control of surface water and roof runoff should be incorporated in the final grading design. In addition to these sources, irrigation and rain water infiltrating into the proposed landscaped and planter areas adjacent to paved areas or building foundations should also be controlled. All collected runoff should be directed into conduits that carry the water away from the pavement or structure and into storm drain systems or other appropriate outlets and should not be discharged onto the slope. Adequate surface gradients should be incorporated into the grading design such that surface runoff is directed away from structures. 5.6 PERMANENT SLOPES It is our opinion that permanent slopes should be graded no steeper than 2H:IV. It is also our opinion that permanent slopes against the foundation or retaining wall should be graded no steep than 3H:IV. 18-358 550 main street, edmonds 8 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 6.0 CONSTRUCTION CONSIDERATIONS 6.1 FOOTING SUBGRADE Any loose or softened soil should be removed from the foundation excavation. Foundation excavations and over -excavations should be observed by PanGEO to confirm that the exposed subgrade is consistent with the expected conditions and adequate to support the proposed building. Foundation over -excavation, if needed, should extend horizontally at least 1 foot beyond the edge of the footings. The footing subgrade will need to be protected from moisture -related disturbance if works will be performed during wet weather. One option is to pour 2 to 3 inches of lean -mix concrete or 4 to 6 inches of crushed rock on the exposed foundation subgrade to protect against moisture. Alternatively, the reinforcing steel can be prefabricated, and the placement of the steel and concrete can be placed immediately after the footing excavation is completed. This will minimize the exposure of the footing subgrade to moisture. 6.2 TEMPORARY EXCAVATION AND DEWATERING All temporary excavations should be performed in accordance with Part N of WAC (Washington Administrative Code) 296-155. Excavations more than 4 feet should be sloped or shored. The contractor is responsible for maintaining safe excavation slopes and/or shoring. For planning purposes, the temporary unsupported excavation may be sloped as steep as 1 H:1 V (Horizontal:Vertical). If areas of seepage are encountered during construction, the above - referenced angles of slope cuts may need to be flattened. We anticipate that the excavation will not be significantly impacted by groundwater. If groundwater seepage is encountered, we anticipate that the use of drainage ditches and sump pumps will provide adequate construction dewatering. 6.3 STRUCTURAL FILL AND COMPACTION The on -site soils generally have a high fines content, and are not suitable to be used as structural fill. For planning and budgeting purposes, we recommend granular import fill such as the City of Seattle Type 17 Mineral Aggregates (Section 9.03.10 (1) of the 2017 Seattle Standard Specifications) or Gravel Borrow (Section 9.03.14 (1) of the 2018 WSDOT Standard Specifications). 18-358 550 main street, edmonds 9 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 Soil Compaction — The structural fill should be moisture conditioned to near its optimum moisture content, placed in loose, horizontal lifts less than about 12 inches in thickness, and systematically compacted to a dense and relatively unyielding condition. The adequacy of the compaction should be verified by PanGEO. If density tests will be performed, the test results should indicate at least 95 percent of the maximum dry density, as determined using test method ASTM D 1557. Within 5 feet of the wall, the backfill should be compacted to 90 percent of the maximum dry density. 6.4 EROSION AND DRAINAGE CONSIDERATIONS We recommend that the exposed slopes be covered with plastic sheeting. Surface runoff can be controlled during construction by careful grading practices. This could include the construction of shallow, upgrade perimeter ditches or low earthen berms in conjunction with silt fences to collect runoff and prevent water from entering excavations. Temporary erosion control may require the use of hay bales on the downhill side of the project to prevent water from leaving the site and potential storm water detention to trap sand and silt before the water is discharged to a suitable outlet. 6.5 WET EARTHWORK RECOMMENDATIONS It is our opinion that construction of the project can be accomplished during wet season. However, performing earthwork activities during wet season is anticipated to be more costly than during dry weather conditions. General recommendations relative to earthwork performed in wet weather or in wet conditions are presented below: • All footing surface should be protected against inclement weather unless the footings can be poured immediately after the subgrade is exposed. It is the contractor's responsibility to protect the footing subgrade from disturbance. One option is to place 2 to 3 inches of lean -mix concrete or 4 to 6 inches of crushed rock on the exposed foundation subgrade as soon as the subgrade is exposed. Alternatively, the footing pour may be made immediately after the footing excavation is completed. This will require the reinforcing steel to be pre -fabricated and lowered into the footing excavation once the excavation is completed. • Earthwork should be performed in small areas to minimize subgrade exposure to wet weather. Excavation or the removal of unsuitable soil should be followed promptly 18-358 550 main street, edmonds 10 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 by the placement and compaction of clean structural fill. The size and type of construction equipment used may have to be limited to prevent soil disturbance. • During wet weather, the allowable fines content of the structural fill should be reduced to no more than 5 percent by weight based on the portion passing 3/4-inch sieve. The fines should be non -plastic. • The ground surface within the construction area should be graded to promote run-off of surface water and to prevent the ponding of water. • Geotextile silt fences should be strategically located to control erosion and the movement of soil. Erosion control measures should be installed along all the property boundaries. • Excavation slopes and soils stockpiled on site should also be covered with plastic sheets. 6.6 INFILTRATION CONSIDERATIONS Based on the site soil and groundwater conditions encountered in our test borings (i.e., multiple perched groundwater zones and iron staining), from the geotechnical engineering perspective, it is our opinion that infiltration of stormwater is not feasible at the site. It is our opinion that non - infiltration design approaches should be considered for stormwater management for this project. 7.0 LIMITATIONS We have prepared this report for use by Seattle -Snohomish Mill Company, Inc. and the project design team. Recommendations contained in this report are based on a site reconnaissance, review of pertinent subsurface information, a subsurface exploration program, and our understanding of the project. The study was performed using a mutually agreed -upon scope of work. Variations in soil conditions may exist between the explorations and the actual conditions underlying the site. The nature and extent of soil variations may not be evident until construction occurs. If any soil conditions are encountered at the site that are different from those described in this report, we should be notified immediately to review the applicability of our recommendations. Additionally, we should also be notified to review the applicability of our recommendations if there are any changes in the project scope. 18-358 550 main street, edmonds I I PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 The scope of our work does not include services related to construction safety precautions. Our recommendations are not intended to direct the contractors' methods, techniques, sequences or procedures, except as specifically described in our report for consideration in design. Additionally, the scope of our work specifically excludes the assessment of environmental characteristics, particularly those involving hazardous substances. We are not mold consultants nor are our recommendations to be interpreted as being preventative of mold development. A mold specialist should be consulted for all mold -related issues. This report may be used only by the client and for the purposes stated, within a reasonable time from its issuance. Land use, site conditions (both off and on -site), or other factors including advances in our understanding of applied science, may change over time and could materially affect our findings. Therefore, this report should not be relied upon after 24 months from its issuance. PanGEO should be notified if the project is delayed by more than 24 months from the date of this report so that we may review the applicability of our conclusions considering the time lapse. It is the client's responsibility to see that all parties to this project, including the designer, contractor, subcontractors, etc., are made aware of this report in its entirety. The use of information contained in this report for bidding purposes should be done at the contractor's option and risk. Any party other than the client who wishes to use this report shall notify PanGEO of such intended use and for permission to copy this report. Based on the intended use of the report, PanGEO may require that additional work be performed and that an updated report be reissued. Noncompliance with any of these requirements will release PanGEO from any liability resulting from the use this report. Within the limitation of scope, schedule and budget, PanGEO engages in the practice of geotechnical engineering and endeavors to perform its services in accordance with generally accepted professional principles and practices at the time the Report or its contents were prepared. No warranty, express or implied, is made. We appreciate the opportunity to be of service to you on this project. Please feel free to contact our office with any questions you have regarding our study, this report, or any geotechnical engineering related project issues. 18-358 550 main street, edmonds 12 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 Sincerely, PanGEO, Inc. Spenser Scott Staff Geologist LAB "9 ti ,Q 30342 0FG/Shy Slo A L E Siew L. Tan, P.E. Principal Geotechnical Engineer 18-358 550 main street, edmonds 13 PanGEO, Inc. Geotechnical Report Main Street Commons: 550 Main Street, Edmonds, Washington November 14, 2018 8.0 REFERENCES ASTM International (ASTM), Annual book of standards, Section 04.08 Soil and Rock (1): D420- D5876: West Conshohocken, Pennsylvania City of Seattle, 2017, Standard Specifications for Road, Bridges, and Municipal Construction, Seattle, Washington. International Building Code (IBC), 2015, International Code Council. Minard, J.P., 1983, Geologic map of the Edmonds East and part of the Edmonds West Quadrangles, Washington: U.S. Geological Survey Miscellaneous Field Studies Map MF- 1541, scale 1:24000. Washington State Department of Transportation (WSDOT), 2018, Standard Specifications for Road, Bridges, and Municipal Construction, Olympia, Washington. Washington Administrative Code (WAC), 2013, Chapter 296-155 - Safety Standards for Construction Work, Part N - Excavation, Trenching, and Shoring, Olympia, Washington. 18-358 550 main street, edmonds 14 PanGEO, Inc. Edmonds - KiRgsto,7., Bracken's Landing Shoreline Sanctuary .. Bracken's Landing North Edmonds Kingston Q Ferry Toll Booth Dayton St w to > e to Edmonds Marsh Caspws St THE BOWL OF EDMONDS Lis • , :: Main St Project Site Marina Beach Park Edmonds City Park � I PINE PARK NEIGHBORHOOD i a g Base Map: Google Terrain y' NORTH iWASHINGTON Alt.. Not to Scale PanGEO Proposed Development VICINITY MAP 550 Main Stre et jest I N C O R P O R A T E D Edmonds, irI'rolect Na 18-358 Figure Nc 1 1 � wruvlan w w j Asphalt / Fo�no \ - iSu'foce Mon/ LL W --7 I 17 tr PVC \ P rkba Now Foq Lhla 1 \ 3 Hour 7.17 1r PVC \ Flao Perking \ U .67 12' PVC i i m uu Pd♦ � 17 .�anlyeta, - W O' CpnO Concrw F}'1 j vQ crets . - , ,3 • -• Ban •N. Concrete Walk ~� Cllarpa irrlgatlon • St ped Brldc Cone �p Ce T e 1 • u, v �, 19.97 CC ' 1� o CB T e PG 3 GE 81.82 wen RIo c fir!ok WaA� S IE NW 78.97 12' P A PG-2 I I 0i T E E 79.07 12' DI / 1' II. n e 9TM .48 IE S 80.32 4' PVC 85.98 - i 1 NW BTU 77.97 n 1 NE IE N 84.55 Ir PVC I CB 1• 1 w rn i E S 84.58 d OP Solid Lid c Idm9 1J542 - BTM 84.38 J I OE 91.42 IEN89.179"01 i Alohdt peon IE E 89,17 12' DI t IE S 89.17 a CID IEWeu.226'01 STM 87.07 pQT91E 0 92.0' Ff +@na�ssgn S3+:ining k55U _ l �� -4 rn m o_ I PG iIl rJ8.592.0ro.l g GE n l L n 0 IIEN84. 6• 7 Em IE S 84.8 8' BTM 84.4 c• 88.9I U O IE E 52 8' CP t , m E S 8�.51 8' Cp cl � 4.T a a PG eTMi8j777 ;1 't QUIVIld N I� IE 83.99 I \ 1 2 i s ♦ e J��!!! L r 3 N 89-58$3" . 59.98 '58'S3" �� 18. '` Approx. Scale 1"=30' Legend: Base map modified from Site Plan by DiMarco Architecture, dated October 31, 2018 Approx. Boring Locations PanGEO, Inc., November 2018 PMGE(D Proposed Development SITE AND EXPLORATION PLAN 550 Main Street I N C O R P O R A T E D Edmonds, WA 18-358 Sure NI' 2 Asphalt Street APPENDIX A SUMMARY BORING LOGS RELATIVE DENSITY / CONSISTENCY SAND / GRAVEL SILT / CLAY SPT Approx. Relative SPT Approx. Undrained Shear DensityN-values Density (%) Consistency N-values Strength (psf) Very Loose <4 <15 Very Soft <2 <250 Loose 4 to 10 15.35 Soft 2 to 4 250.500 Med. Dense 10 to 30 35.65 Med. Stiff 4 to 8 500.1000 Dense 30 to 50 65.85 Stiff 8 to 15 1000.2000 Very Dense >50 85.100 Very Stiff 15 to 30 2000.4000 Hard >30 >4000 UNIFIED SOIL CLASSIFICATION SYSTEM MAJOR DIVISIONS GROUP DESCRIPTIONS •�' GW: Well -graded GRAVEL Gravel GRAVEL (<5% fines) '' •••••I...................................................... 50% or more of the coarse GP : Poorly -graded GRAVEL fraction retained on the #4 sieve. Use dual symbols (eg. ............................. o ° .....:...................................................... GM Silty GRAVEL GP -GM) for 5% to 12% fines. o GRAVEL(>12/ofines) •••••••••••••••••••••••••••••• GC : ........................••• Clayey GRAVEL ...................................................................... .......................................................... SW: Well -graded SAND "" Sand SAND (<5/o fines) 50% or more of the coarse SP Poorly -graded SAND fraction passing the 94 sieve. Use dual symbols SP-SM) •• ••� �• ;; ; SM : Silty SAND for 5%to12%fines. o •SAND(>12/o fines) ••••••••••••••••••••••••••••••••••••••••••••••••••••••••• SC : Clayey SAND •• ...............................•• ............................. ............................................................ MIL : : SILT Liquid Limit < 50 CL : ............................................................ ...................................................... Lean CLAY Silt and Clay =— _— OL : Organic SILT or CLAY 50%or more passing #200 sieve :.................................. ......................................................... MH : Elastic SILT Liquid Limit > 50 CH Fat CLAY ..............................-................................. OH ............................................................ Organic SILT or CLAY _ , HighlyOrganic Soils PT : PEAT Notes: 1. Soil exploration to s contain material descriptions based on visual observation and field tests using a system modified from the Uniform Soil Classification System (USCS). Where necessary laboratory tests have been conducted (as noted in the "Other Tests" column), unit descriptions may include a classification. Please refer to the discussions in the report text for a more complete description of the subsurface conditions. 2. The graphic symbols given above are not inclusive of all symbols that may appear on the borehole logs. Other symbols may be used where field observations indicated mixed soil constituents or dual constituent materials. DESCRIPTIONS OF SOIL STRUCTURES Layered: Units of material distinguished by color and/or Fissured: Breaks along defined planes composition from material units above and below Slickensided: Fracture planes that are polished or glossy Laminated: Layers of soil typically 0.05 to 1 mm thick, max. 1 cm Blocky: Angular soil lumps that resist breakdown Lens: Layer of soil that pinches out laterally Disrupted: Soil that is broken and mixed Interlayered: Alternating layers of differing soil material Scattered: Less than one per foot Pocket: Erratic, discontinuous deposit of limited extent Numerous: More than one per foot Homogeneous: Soil with uniform color and composition throughout BCN: Angle between bedding plane and a plane normal to core axis COMPONENT DEFINITIONS COMPONENT SIZE / SIEVE RANGE COMPONENT SIZE / SIEVE RANGE Boulder: > 12 inches Sand Cobbles: 3 to 12 inches Coarse Sand: #4 to #10 sieve (4.5 to 2.0 mm) Gravel Medium Sand: #10 to #40 sieve (2.0 to 0.42 mm) Coarse Gravel: 3 to 3/4 inches Fine Sand: #40 to #200 sieve (0.42 to 0.074 mm) Fine Gravel: 3/4 inches to #4 sieve Silt 0.074 to 0.002 mm Clay <0.002 mm TEST SYMBOLS for In Situ and Laboratory Tests listed in "Other Tests" column. ATT Atterberg Limit Test Comp Compaction Tests Con Consolidation DID Dry Density DS Direct Shear %F Fines Content GS Grain Size Perm Permeability PP Pocket Penetrometer R R-value SG Specific Gravity TV Torvane TXC Triaxial Compression UCC Unconfined Compression SYMBOLS Sample/In Situ test types and intervals ®2-inch OD Split Spoon, SPT (140-lb. hammer, 30" drop) B3.25-inch OD Spilt Spoon (300-lb hammer, 30" drop) Non-standard penetration test (see boring log for details) Thin wall (Shelby) tube Grab Rock core ® Vane Shear MONITORING WELL SZ Groundwater Level at time of drilling (ATD) 1 Static Groundwater Level Cement / Concrete Seal Bentonite grout / seal Silica sand backfill Slotted tip Slough Bottom of Boring MOISTURE CONTENT Dry Dusty, dry to the touch Moist Damp but no visible water Wet Visible free water PanGE@) Terms and Symbols for I N C O R P O R A T E D Boring and Test Pit Logs Figure A-1 Phone: 206.262.0370 Project: 550 Main Street Surface Elevation: 87.Oft Job Number: 18-358 Top of Casing Elev.: N/A Location: 550 Main Street, Edmonds, WA Drilling Method: HSA Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A $ o Z a) c Cn p PL Moisture LL a a ; E MATERIAL DESCRIPTION aa) 0 E E U) 3 D >1 ®ROD RecoveryFA U) m O 0 50 100 O 8-inches of asphalt. Medium dense, moist, brown, slightly silty SAND; trace gravel. (Fill). 13 S-1 10 -- Perched groundwater encountered at approximately 4-feet. 9 Stiff, moist, light -grey, CLAY; trace silt, highly mottled. ......... ......... ......... ......... 5 Medium dense, moist to wet, brown, silty fine to medium SAND; trace 14 gravel, trace iron -oxide staining. S-2X1a 14 (Qtb -Transitional Beds). 12 S-3 13 15 Perched groundwater encountered at approximately 8.5-feet. 10 8 Increase in gravel at approximately 10-feet. S-4 10 10 20 S-5 22 -- Perched groundwater encountered at approximately 13-feet. 20 15 18 Perched groundwater encountered at approximately 15.5-feet. S-6X 20 20 Disrupted layer of blue -grey to grey fines at base of Qtb. 4401 Very dense, moist to wet, blue -grey, silty fine SAND with pebble -sized gravel; slighty cemented, trace mottling. 20 (Qog - Olympia Gravel). S-7 29 32 20 --Groundwater encountered at approximately 20-feet. S 8 50 5 Boring terminated at 21 feet below ground surface. Perched goundwater was observed at approximately 4-feet, 8.5-feet, 10-feet, 13-feet, and 15.5-feet. Final groundwater level after drilling operations was approximately 9.5-feet. 25 ......... ......... Completion Depth: 21.5ft Remarks: Boring drilled using an EC95 track drill rig. Standard penetration test (SPT) Date Borehole Started: 11/7/18 sampler driven with a 140 lb. safety hammer. Hammer operated with a rope and cathead Date Borehole Completed: 11/7/18 mechanism. Surface elevation estimated from Topographic Survey by Emerald Land Logged By: S. Scott Surveying, Inc., dated October 10, 2017. Drilling Company: Boretec 1 PmGE& LOG OF TEST BORING PG-1 I N C D R P O R A T■ D Figure A-2 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 1 Of 1 Project: 550 Main Street Surface Elevation: 87.Oft Job Number: 18-358 Top of Casing Elev.: N/A Location: 550 Main Street, Edmonds, WA Drilling Method: HSA Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A $ o Z a) c Cn p PL Moisture LL a a ; E MATERIAL DESCRIPTION aa) 0 E E U) 3 D >1 ®ROD RecoveryFA U) m O 0 50 100 O 4-inches of asphalt. Medium dense, moist, brown, slightly silty fine to medium SAND; trace gravel, trace iron -oxide staining. (Fill). 4 S-1 5 15 Dense to very dense, moist to wet, grey -brown, silty fine to medium 5 SAND; trace gravel, trace silt stringers, trace iron -oxide staining. 16 (Qtb -Transitional Beds). S-2 21 Perched groundwater encountered at approximately 5-feet. 23 21 S-3 30 33 10 49 S-4 33 Perched groundwater and increased gravels encountered at 39 approximately 11-feet. Boring terminated at 11.5 feet below ground surface. Perched groundwater was observed at approximately 5-feet and 11-feet. No groundwater was observed at the bottom of the hole after drilling operations. 15 20 ......... ......... 25 Completion Depth: 11.5ft Remarks: Boring drilled using an EC95 track drill rig. Standard penetration test (SPT) Date Borehole Started: 11/7/18 sampler driven with a 140 lb. safety hammer. Hammer operated with a rope and cathead Date Borehole Completed: 11/7/18 mechanism. Surface elevation estimated from Topographic Survey by Emerald Land Logged By: S. Scott Surveying, Inc., dated October 10, 2017. Drilling Company: Boretec 1 RnGE& LOG OF TEST BORING PG-2 A N C O R P Y R A T■ o Figure A-3 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 1 Of 1 Project: 550 Main Street Surface Elevation: 91.0ft Job Number: 18-358 Top of Casing Elev.: N/A Location: 550 Main Street, Edmonds, WA Drilling Method: HSA Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A O Z a) Cl C ro Y p PL Moisture LL a a ; E MATERIAL DESCRIPTION aQi p E E ) 11 Recovery CO U m O 0 50 100 0 -- 5-inches of asphalt. Medium dense, moist, grey to brown, slightly silty SAND with gravel. (Fill). 10 S-1 X 10 11 Dense, moist to wet, brown, silty fine SAND with gravel; trace silt 5 stringers, trace iron -oxide staining. 19 (Qtb -Transitional Beds). S-2 23 24 17 -- Perched groundwater encountered at approximately 7.5-feet. S-3 X 19 20 10 13 S-4 X 16 17 Boring terminated at 11.5 feet below ground surface. Perched groundwater was observed at approximately 7.5-feet. No groundwater was observed at the bottom of the hole after drilling operations. 15 20 ......... ......... 25 Completion Depth: 11.5ft Remarks: Boring drilled using an EC95 track drill rig. Standard penetration test (SPT) Date Borehole Started: 11/7/18 sampler driven with a 140 lb. safety hammer. Hammer operated with a rope and cathead Date Borehole Completed: 11/7/18 mechanism. Surface elevation estimated from Topographic Survey by Emerald Land Logged By: S. Scott Surveying, Inc., dated October 10, 2017. Drilling Company: Boretec 1 LI."! ITA LOG OF TEST BORING PG-3 Pafl-iGJL M < 0 A P 0 R 4*■ D Figure A-4 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 1 Of 1 Project: 550 Main Street Surface Elevation: 90.0ft Job Number: 18-358 Top of Casing Elev.: N/A Location: 550 Main Street, Edmonds, WA Drilling Method: HSA Coordinates: Northing: , Easting: Sampling Method: SPT N-Value A O Z a) Cl C ro Y p PL Moisture LL a a ; E MATERIAL DESCRIPTION aQi p E E ) 11 Recovery CO U m O 0 50 100 0 -- 5-inches of asphalt. Very dense, moist, grey to brown, slightly silty SAND; trace gravel. (Fill). 18 S-1 22 29 Very dense to dense, moist to wet, grey -brown, silty fine SAND; trace 5 coarse sand stringers, trace gravel, trace iron -oxide staining. 18 (Qtb -Transitional Beds). S-2 22 -- Perched groundwater encountered at approximately 5 feet. 28 21 -- Increase in gravel at approximately 5-feet. S-3 21 31 10 17 S-4 20 18 Boring terminated at 11.5 feet below ground surface. Perched groundwater was observed at approximately 5-feet. No groundwater was observed at the bottom of the hole after drilling operations. 15 20 ......... ......... 25 Completion Depth: 11.5ft Remarks: Boring drilled using an EC95 track drill rig. Standard penetration test (SPT) Date Borehole Started: 11/7/18 sampler driven with a 140 lb. safety hammer. Hammer operated with a rope and cathead Date Borehole Completed: 11/7/18 mechanism. Surface elevation estimated from Topographic Survey by Emerald Land Logged By: S. Scott Surveying, Inc., dated October 10, 2017. Drilling Company: Boretec 1 LI."! ITA LOG OF TEST BORING PG-4 Pafl-iGJL M < 0 A P 0 R 4*■ D Figure A-5 The stratification lines represent approximate boundaries. The transition may be gradual. Sheet 1 Of 1 enging eerinp c APPENDIX E Operation and Maintenance Manual IMM engineering pllc Main Street Commons Commercial Development Operations & Maintenance Manual May 7, 2019 Prepared by: LPD Engineering, PLLC 1932 1 st Avenue, Suite 201 Seattle, WA 98101 206.725.1211 Operations & Maintenance Manual Project Overview This Operations and Maintenance Manual is for the Main Street Commons Commercial Development project located at 550 Main Street in Edmonds, Washington. The proposed project involves renovation of the existing on -site building to accommodate space for a restaurant, retail businesses and courtyard area, construction of a new two-story commercial building in the eastern portion of the site to primarily serve retail tenants, and construction of a courtyard area in the remaining site area. Stormwater System Overview The project proposes an onsite detention vault located in the central courtyard area. The detention vault will have a flow control structure, equipped with a riser (with multiple orifices) to manage the stormwater flows. Due to the existing invert elevation at the connection to the public storm system in Main Street a pump system will be designed downstream of the flow control structure. In the existing conditions, runoff from the overall site is primarily generated from the existing building and the existing parking lot. Stormwater runoff from the site conveys northerly and westerly towards the public storm drainage systems in Main Street and 5th Avenue South. The stormwater is conveyed in Shellabarger Creek and is eventually discharged into the Puget Sound. In the proposed conditions, the overall drainage pattern throughout the site will be maintained. The eastern half of the existing building roof will be collected and conveyed to the proposed detention vault. Rain falling upon the proposed roof area will be collected in and conveyed in underground pipe to a detention vault. Similarly, rain falling on the proposed onsite pavers, concrete and asphalt pavement areas will be collected in area drains and trench drains and conveyed in underground pipe to the detention vault. A pump system will be provided downstream of the detention vault and here will be one connection point from the pump structure to the existing storm system in Main Street. The western half of the existing building will continue to discharge to the alley as it currently does. Refer to Figure 5, and also the Drainage Plan Sheet C2.0, included with this manual for a layout of the drainage system. Also refer to Sheets C2.1, and C2.2 for details of the flow control structures, and the detention system. Flow Control Structure Maintenance The flow control structure for the detention system is located in the northeast corner of the detention vault. Refer to the attached guidelines on Table 4.5.2(4) of Volume V from the 2014 Department of Ecology (DOE) Stormwater Management Manual for Western Washington for the flow control structure. Compost Amended Soil Maintenance Compost amended soil will be utilized for all new landscape areas. Refer to the attached maintenance requirements from Table 4.5.2(20) from the 2014 DOE Stormwater Management Manual for compost amended soil. Operations & Maintenance Manual Main Street Commons Commercial Development LPD Engineering, PLLC Page I May 3, 2019 engineeringIpc Detention Vault System Maintenance The detention vault is located in the central courtyard, east of the existing building and west of the proposed building. The vault has two access risers, one on the northeast corner and one on the southwest corner. Refer to the attached maintenance guidelines on Table 4.5.2(3) of Volume V from the 2014 DOE Stormwater Management Manual for Western Washington for closed detention systems (tanks/vaults). Pump System Maintenance Stormwater from the proposed detention will have to be pumped due to the adjacent public storm system being very shallow, and thus not allowing gravity discharge of stormwater. The pump basin will be located downstream of the vault, with a westbound force main taking stormwater to the existing storm system in Main Street. Refer to the pump system inspection and maintenance procedures, as outlined by Goulds Water Technology (manufacturer of pump systems), included with this manual. Catch Basins, Area Drain and Trench drain Maintenance Refer to the attached maintenance guidelines on Table 4.5.2(5) of Volume V from the 2014 DOE Stormwater Management Manual for Western Washington for catch basins. Maintenance Responsibility This Operations and Maintenance Manual shall be kept in the Main Street Commons main office and a copy shall be kept with the property Owner, Seattle -Snohomish Mill Company, Inc. This manual must be made readily available for inspection by City of Edmonds personnel. Seattle - Snohomish Mill Company, Inc is the responsible party for maintenance of the on -site storm systems. Seattle -Snohomish Mill Company, Inc can be contacted at (425) 263-2474. The maintenance activity log shall be kept up date with the most current O&M actions by Seattle - Snohomish Mill Company and shall be made available for inspection by the City upon request. Operations & Maintenance Manual Main Street Commons Commercial Development LPD Engineering, PLLC Page 2 May 3, 2019 engineeringIpc Attachments: • Exhibit A - Stormwater Facilities Site Map • Drainage Plan Sheet C2.0; Drainage Details Sheet C2.1-C2.2; • Operation and Maintenance Guidelines from the 2014 Department of Ecology Stormwater Management Manual for Western Washington • Sample Maintenance Activity Log Operations & Maintenance Manual Main Street Commons Commercial Development LPD Engineering, PLLC Page 3 May 3, 2019 • CONTROL PUMP TRENC CONNECTSTRUCTURE STRUCTURE • STORM SYSTEM ...........::: MA�N STREET .............. -, ..... .....€ t 10% '�� 1..... m ►l ��I I , fi'IIIllftlld�L:!'iJ®111111®1 er.l�illill� �TRENCH DR �FIII ETRENCH TENTIO .- .-. EXHIBIT A - STORMWATER FACILITIES SITE MAP MAIN STREET COMMONS Table V-4.5.2(3) Maintenance Standards - Closed Detention Systems (Tanks/Vaults) Results Expec Maintenance Defect Conditions When Maintenance is ted When Component Needed Maintenance is Performed Plugged Air One-half of the cross section of a vent Vents open and Vents is blocked at any point or the vent is functioning. damaged. Accumulated sediment depth exceeds 10% of the diameter of the storage area for 1/2 length of storage vault or any All sediment Debris and Sed- point depth exceeds 15% of diameter. and debris iment (Example: 72-inch storage tank would removed from require cleaning when sediment storage area. reaches depth of 7 inches for more than 1/2 length of tank.) Any openings or voids allowing mater- All joint Joints Between ial to be transported into facility. between Storage Area Tank/Pipe Sec- tank/pipe sec- tion (Will require engineering analysis to tions are determine structural stability). sealed. Any part of tank/pipe is bent out of Tank/pipe Tank Pipe Bent shape more than 10% of its design repaired or Out of Shape shape. (Review required by engineer to replaced to determine structural stability). design. Cracks wider than 1/2-inch and any Vault replaced evidence of soil particles entering the or repaired to Vault Structure structure through the cracks, or main- g design spe- cifications and Includes Cracks tenance/inspection personnel determ- is structurally in Wall, Bottom, ines that the vault is not structurally sound. Damage to sound. Frame and/or Cracks wider than 1/2-inch at the joint No cracks more Top Slab of any inlet/outlet pipe or any evidence than 1/4-inch of soil particles entering the vault wide at the joint through the walls. of the inlet/out- let pipe. Manhole Cover Not in Cover is missing or only partially in Manhole is Place place. Any open manhole requires closed. maintenance. 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 835 Table V-4.5.2(3) Maintenance Standards - Closed Detention Systems (Tanks/Vaults) (continued) Results Expec Maintenance Defect Conditions When Maintenance is ted When Component Needed Maintenance is Performed Mechanism cannot be opened by one Locking Mech- maintenance person with proper tools. Mechanism anism Not Work- Bolts into frame have less than 1/2 inch opens with ing of thread (may not apply to self-locking proper tools. lids). Cover can be One maintenance person cannot removed and Cover Difficult to remove lid after applying normal lifting reinstalled by Remove pressure. Intent is to keep cover from one main - sealing off access to maintenance. tenance per- son. Ladder meets Ladder is unsafe due to missing rungs, design stand - Ladder Rungs misalignment, not securely attached to ards. Allows Unsafe structure wall, rust, or cracks. maintenance person safe access. Catch Basins See "Catch Bas- See "Catch Basins" (No. 5). See "Catch ins" (No. 5) Basins" (No. 5). Table V-4.5.2(4) Maintenance Standards - Control Structure/Flow Restrictor Maintenance Component Defect Condition When Main- tenance is Needed Results Expected When Maintenance is Performed Trash and Material exceeds 25% of Control structure orifice is not Debris sump depth or 1 foot below blocked. All trash and debris (Includes orifice plate. removed. Sediment) General Structure is not securely Structure securely attached to attached to manhole wall. wall and outlet pipe. Structural Structure is not in upright Structure in correct position. Damage position (allow up to 10% Connections to outlet pipe are from plumb). watertight; structure repaired Connections to outlet pipe or replaced and works as 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 836 Table V-4.5.2(4) Maintenance Standards - Control Structure/Flow Restrictor (continued) Maintenance Defect Condition When Main- Results Expected When Component tenance is Needed Maintenance is Performed are not watertight and show signs of rust. designed. Any holes - other than Structure has no holes other designed holes - in the than designed holes. structure. Cleanout gate is not water- Gate is watertight and works tight or is missing. as designed. Gate cannot be moved up Gate moves up and down eas- Cleanout Damaged or and down by one main- tenance person. ily and is watertight. Gate Missing Chain is in place and works as Chain/rod leading to gate is designed. missing or damaged. Gate is rusted over 50% of Gate is repaired or replaced to its surface area. meet design standards. Control device is not work - Damaged or ing properly due to missing, Plate is in place and works as Orifice Plate Missing out of place, or bent orifice designed. plate. Any trash, debris, sediment, Plate is free of all obstructions Obstructions or vegetation blocking the and works as designed. plate. Overflow Any trash or debris blocking Pipe is free of all obstructions Pipe Obstructions (or having the potential of and works as designed. blocking) the overflow pipe. See "Closed Manhole Detention See "Closed Detention Sys -See "Closed Detention Sys - Systems" tems" (No. 3). tems" (No. 3). (No. 3). See "Catch Catch Basin Basins" (No. See "Catch Basins" (No. 5). See "Catch Basins" (No. 5). 5). 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 837 Table V-4.5.2(19) Maintenance Standards - Media Filter Drain (MFD) (continued) Maintenance Conditions When Main- Results Expected When Defect Maintenance is Per- Component tenance is Needed formed brushy vegetation on adja- embankment. cent slopes. Trash and Trash and debris have accu- Remove trash and debris debris mulated on embankment. from embankment. Evaluate media filter drain material for acceptable Flooding of When media filter drain is infiltration rate and replace Media filter inundated by flood water if media filter drain does drain not meet long-term infilt- ration rate standards. Table V-4.5.2(20) Maintenance Standards - Compost Amended Vegetated Filter Strip (CAVFS) Conditions Maintenance Defect When Main- Results Expected When Maintenance Component tenance is is Performed Needed Sediment accu- Sediment Remove sediment deposits. Relevel so mulation on depth exceeds slope is even and flows pass evenly grass 2 inches. through strip. Grass becomes excessively tall (greater than 10 Mow grass and control nuisance veget- Vegetation inches); nuis- ation so that flow is not impeded. Grass should be mowed to a height of 6 General ance weeds inches. and other vegetation start to take over. Trash and debris have Trash and debris accumulated Remove trash and debris from filter. on the veget- ated filter strip. 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 861 Table V-4.5.2(20) Maintenance Standards - Compost Amended Vegetated Filter Strip (CAVFS) (continued) Maintenance Component Defect Conditions When Main- tenance is Needed Results Expected When Maintenance is Performed For ruts or bare areas less than 12 inches wide, repair the damaged area by Areas have filling with a 50/50 mixture of crushed eroded or gravel and compost. The grass will Erosion/scouring scoured due creep in over the rock in time. If bare to flow chan- areas are large, generally greater than nelization or 12 inches wide, the vegetated filter strip high flows. should be regraded and reseeded. For smaller bare areas, overseed when bare spots are evident. Flow spreader is uneven or clogged so Level the spreader and clean so that Flow spreader that flows are flows are spread evenly over entire filter not uniformly width distributed over entire fil- ter width. Table V-4.5.2(21) Maintenance Standards - Bioretention Facilities Recommended Fre- Condition Maintenance quency a when Main- Action Needed (Pro - Component tenance is cedures p Routine Main -Needed (Stand- ) Inspection tenance ards) Facility Footprint Earthen side slopes and B, S berms Eliminate cause of Erosion (gullies/ erosion and stabilize rills) greater damaged area than 2 inches (regrade, rock, veget. deep around ation, erosion control inlets, outlet, matting) and alongside . For deep channels slopes or cuts (over 3 inches in ponding 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 862 Table V-4.5.2(5) Maintenance Standards - Catch Basins Results Maintenance Conditions When Maintenance is Expected Defect When Main- Component Needed tenance is performed No Trash or debris loc- Trash or debris which is located imme- ated imme- diately in front of the catch basin opening or diately in is blocking inletting capacity of the basin by front of catch more than 10%. basin or on Trash or debris (in the basin) that exceeds grate open- 60 percent of the sump depth as measured ing. from the bottom of basin to invert of the low- No trash or est pipe into or out of the basin, but in no debris in the Trash & case less than a minimum of six inches catch basin. Debris clearance from the debris surface to the invert of the lowest pipe. Inlet and out- let pipes free Trash or debris in any inlet or outlet pipe of trash or blocking more than 1/3 of its height. debris. General Dead animals or vegetation that could gen- No dead erate odors that could cause complaints or animals or dangerous gases (e.g., methane). vegetation present within the catch basin. Sediment (in the basin) that exceeds 60 per- cent of the sump depth as measured from the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case No sediment Sediment less than a minimum of 6 inches clearance in the catch from the sediment surface to the invert of the basin lowest pipe. Structure Top slab has holes larger than 2 square Top slab is Damage to inches or cracks wider than 1/4 inch. (Intent free of holes Frame and/or is to make sure no material is running into and cracks. Top Slab basin). Frame is sit- 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 838 Table V-4.5.2(5) Maintenance Standards - Catch Basins (continued) Results Maintenance Conditions When Maintenance is Expected Component Defect Needed When Main- tenance is performed Frame not sitting flush on top slab, i.e., sep- ting flush on aration of more than 3/4 inch of the frame the riser rings from the top slab. Frame not securely or top slab attached and firmly attached. Basin Maintenance person judges that structure is replaced or unsound. repaired to Fractures or design stand - Cracks in Grout fillet has separated or cracked wider ards. Basin Walls/ longer than 1 foot at the than 1/2 inch and Ion g Bottom joint of any inlet/outlet pipe or any evidence Pipe is of soil particles entering catch basin through regrouted cracks. and secure at basin wall. Basin Settlement/ If failure of basin has created a safety, func- replaced or Misalignment tion, or design problem. repaired to design stand- ards. No veget- Vegetation growing across and blocking ation block - more than 10% of the basin opening. ing opening to basin. Vegetation Vegetation growing in inlet/outlet pipe joints No that is more than six inches tall and less veget- than six inches apart. ation or root growth present. Contamination See "Detention Ponds" (No. 1). No pollution and Pollution present. Cover Not in Cover is missing or only partially in place. Catch basin Catch Basin Place Any open catch basin requires main- cover is tenance. closed Cover Locking Mech- Mechanism cannot be opened by one main- Mechanism anism Not tenance person with proper tools. Bolts into opens with 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 839 Table V-4.5.2(5) Maintenance Standards - Catch Basins (continued) Results Maintenance Conditions When Maintenance is Expected Component Defect Needed When Main- tenance is performed Working frame have less than 1/2 inch of thread. proper tools. One maintenance person cannot remove lid Cover can be Cover Difficult after applying normal lifting pressure. removed by to Remove (Intent is keep cover from sealing off access one main - tenance per - to maintenance.) son. Ladder meets design stand Ladder Rungs Ladder is unsafe due to missing rungs, not ards and Ladder Unsafe securely attached to basin wall, mis- allows main - alignment, rust, cracks, or sharp edges. tenance per- son safe access. Grate open - Grate opening Grate with opening wider than 7/8 inch. ing meets Unsafe design stand- ards. Metal Grates Trash and Trash and debris that is blocking more than Grate free of (If Applic- Debris 20% of grate surface inletting capacity. trash and able) debris. Grate is in Damaged or Grate missing or broken member(s) of the place and Missing. grate. meets design standards. Table V-4.5.2(6) Maintenance Standards - Debris Barriers (e.g., Trash Racks) Maintenance Condition When Maintenance is Results Expected Com- Defect When Maintenance is ponents Needed Performed Trash and Trash or debris that is plugging Barrier cleared to design General Debris more than 20% of the openings in flow capacity. the barrier. Damaged/ Bars are bent out of shape more Bars in place with no Metal Missing than 3 inches. bends more than 3/4 2014 Stormwater Management Manual for Western Washington Volume V - Chapter 4 - Page 840 Maintenance Activity Log To be completed by maintenance staff and provided to the City of Edmonds upon request. Property Name/Owner: Site Address: Property Manager/Contact: Phone: Facility Type: Location on Property: Requirement met by Facility (circle all that apply): On -site Stormwater Management Treatment/Water Quality Flow Control Date Reason for Condition Observed Action Taken Initials Inspection/Action circle one Complaint or Problem Regular Maintenance Complaint or Problem Regular Maintenance Complaint or Problem Regular Maintenance Complaint or Problem Regular Maintenance Complaint or Problem Regular Maintenance Complaint or Problem Regular Maintenance Complaint or Problem Regular Maintenance enging eerinp c APPENDIX F Bond Quantity Worksheet Site Improvement Bond Quantity Worksheet S15 Webdate: 04/03/201E L14 King County Department of Permitting & Environmental Review 35030 SE Douglas Street, Suite 210 Snoqualmie, Washington 98065-9266 206-296-6600 TTY Relay 711 Project Name: Main Street Commons Commercial Development Location: 550 Main Street, Edmonds, WA 98020 Clearing greater than or equal to 5,000 board feet of timber? yes X no If yes, Forest Practice Permit Number: (RCW 76.09) Page 1 of 9 KC Bond Quantity Worksheet 2020-09 For alternate formats, call 206-296-6600. Date: 9/1 /2020 Project No.: Activity No.: Note: All prices include labor, equipment, materials, overhead and profit. Prices are from IRS Means data adjusted for the Seattle area or from local sources if not included in the IRS Means database. Unit prices updated: 3/2/2015 Version: 3/2/2015 Report Date: 9/1 /2020 Site Improvement Bond Quantity Worksheet S15 Webdate: 04/03/201E Reference # Unit Price Unit Quantity # of Applications Cost EROSION/SEDIMENT CONTROL Number Backfill & compaction -embankment ESC-1 $ 6.00 CY Catch basin inserts $ 25.00 Each 5 1 125 Check dams, 4" minus rock ESC-2 SWDM 5.4.6.3 $ 80.00 Each Crushed surfacing 1 1/4" minus ESC-3 WSDOT 9-03.9(3) $ 95.00 CY Ditching ESC-4 $ 9.00 CY Excavation -bulk ESC-5 $ 2.00 CY Fence, silt ESC-6 SWDM 5.4.3.1 $ 1.50 LF Fence, Temporary (NGPE) ESC-7 $ 1.50 LF 400 1 600 Hydroseeding ESC-8 SWDM 5.4.2.4 $ 0.80 SY Jute Mesh ESC-9 SWDM 5.4.2.2 $ 3.50 SY Mulch, by hand, straw, 3" deep ESCA0 SWDM 5.4.2.1 $ 2.50 SY Mulch, by machine, straw, 2" deep ESCA 1 SWDM 5.4.2.1 $ 2.00 SY Piping, temporary, CPP, 6" ESC-12 $ 12.00 LF Piping, temporary, CPP, 8" ESCA3 $ 14.00 LF Piping, temporary, CPP, 12" ESC-14 $ 18.00 LF Plastic covering, 6mm thick, sandbagged ESCA5 SWDM 5.4.2.3 $ 4.00 SY 75 1 300 Rip Rap, machine placed; slopes ESCA6 WSDOT 9-13.1(2) $ 45.00 CY Rock Construction Entrance, 50'x15'x1' ESCA7 SWDM 5.4.4.1 $ 1,800.00 Each Rock Construction Entrance, 100'x15'x1' ESC-18 SWDM 5.4.4.1 $ 3,200.00 Each Sediment pond riser assembly ESC-19 SWDM 5.4.5.2 $ 2,200.00 Each Sediment tank $ 5,000.00 Each 1 1 5000 Sediment trap, 5' high berm ESC-20 SWDM 5.4.5.1 $ 19.00 LF Sed. trap, 5' high, riprapped spillway berm section ESC-21 SWDM 5.4.5.1 $ 70.00 LF Seeding, by hand Sodding, 1" deep, level ground ESC-22 SWDM 5.4.2.4 $ 1.00 SY ESC-23 SWDM 5.4.2.5 $ 8.00 SY Sodding, 1" deep, sloped ground ESC-24 SWDM 5.4.2.5 $ 10.00 SY TESC Supervisor ESC-25 $ 110.00 HR 1 Water truck, dust control ESC-26 SWDM 5.4.7 $ 140.00 HR WRITE -IN -ITEMS **** (see page 9) Each KC Bond Quantity Worksheet 2020-09 ESC SUBTOTAL: $ 6,025.00 30% CONTINGENCY & MOBILIZATION: $ 1,807.50 ESC TOTAL: $ 7,832.50 Unit prices updated: 3/2/2015 Version: 3/2/2015 Report Date: 9/1 /2020 Site Improvement Bond Quantity Worksheet S15 Webdate: 04/03/201E COLUMN: A Page 2 of 9 KC Bond Quantity Worksheet 2020-09 Unit prices updated: 3/2/2015 Version: 3/2/2015 Report Date: 9/1 /2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Right -of -Way Future Public Right of Way & Drainage Facilities Private Improvements Unit Price Unit Quant. Cost Quant. Cost Quant. Cost GENERAL ITEMS No. Backfill & Compaction- embankment GI - 1 $ 6.00 CY Backfill & Compaction- trench GI - 2 $ 9.00 CY Clear/Remove Brush, by hand GI - 3 $ 1.00 SY Clearing/Grubbing/Tree Removal GI - 4 $ 10,000.00 Acre Excavation - bulk GI - 5 $ 2.00 CY 425 850.00 Excavation - Trench GI - 6 $ 5.00 CY Fencing, cedar, 6' high GI - 7 $ 20.00 LF Fencing, chain link, vinyl coated, 6' high GI - 8 $ 20.00 LF Fencing, chain link, gate, vinyl coated, 20' GI-9 $ 1,400.00 Each Fencing, split rail, 3' high GI - 10 $ 15.00 LF Fill & compact - common barrow GI - 11 $ 25.00 CY Fill & compact - gravel base GI - 12 $ 27.00 CY Fill & compact - screened topsoil GI - 13 $ 39.00 CY Gabion, 12" deep, stone filled mesh GI - 14 $ 65.00 SY Gabion, 18" deep, stone filled mesh GI - 15 $ 90.00 SY Gabion, 36" deep, stone filled mesh GI - 16 $ 150.00 SY Grading, fine, by hand GI - 17 $ 2.50 SY Grading, fine, with grader GI - 18 $ 2.00 SY Monuments, 3' long GI - 19 $ 250.00 Each Sensitive Areas Sign GI - 20 $ 7.00 Each Sodding, 1" deep, sloped ground GI - 21 $ 8.00 SY Surveying, line & grade GI - 22 $ 850.00 Day Surveying, lot location/lines GI - 23 $ 1,800.00 Acre Traffic control crew ( 2 flaggers) GI - 24 $ 120.00 HR Trail, 4" chipped wood GI - 25 $ 8.00 SY Trail, 4" crushed cinder GI - 26 $ 9.00 SY Trail, 4" top course GI - 27 $ 12.00 SY Wall, retaining, concrete GI - 28 $ 55.00 SF Wall, rockery GI - 29 $ 15.00 SF Page 3 of 9 "KCC 27A authorizes only one bond reduction. KC Bond Quantity W orksheet 2020-09 SUBTOTAL 850.00 Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 9/1/2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Right-of-way Future Public Right of Way & Drainage Facilities Private Improvements Unit Price Unit Quant. Cost Quant. Cost Quant. Cost ROAD IMPROVEMENT No. AC Grinding, 4' wide machine < 1000sy RI - 1 $ 30.00 SY AC Grinding, 4' wide machine 1000-2000 RI - 2 $ 16.00 SY AC Grinding, 4' wide machine > 2000sy RI - 3 $ 10.00 SY AC Removal/Disposal RI - 4 $ 35.00 SY 65 2,275.00 1275 44,625.00 Barricade, type III ( Permanent) RI - 6 $ 56.00 LF Curb & Gutter, rolled RI - 7 $ 17.00 LF Curb & Gutter, vertical RI - 8 $ 12.50 LF 65 812.50 Curb and Gutter, demolition and disposal RI - 9 $ 18.00 LF 16 288.00 Curb, extruded asphalt RI - 10 $ 5.50 LF Curb, extruded concrete RI - 11 $ 7.00 LF Sawcut, asphalt, 3" depth RI - 12 $ 1.85 LF 225 416.25 Sawcut, concrete, per 1" depth RI - 13 $ 3.00 LF Sealant, asphalt RI - 14 $ 2.00 LF Shoulder, AC, ( see AC road unit price ) RI - 15 $ - SY Shoulder, gravel, 4" thick RI - 16 $ 15.00 SY Sidewalk, 4" thick RI - 17 $ 38.00 SY 155 5,890.00 766 29,108.00 Sidewalk, 4" thick, demolition and disposal RI - 18 $ 32.00 SY 116 3,712.00 40 1,280.00 Sidewalk, 5" thick RI - 19 $ 41.00 SY 18 738.00 Sidewalk, 5" thick, demolition and disposal RI - 20 $ 40.00 SY Sign, handicap RI - 21 $ 85.00 Each 1 85.00 Striping, per stall RI - 22 $ 7.00 Each 8 56.00 Striping, thermoplastic, ( for crosswalk ) RI - 23 $ 3.00 SF Striping, 4" reflectorized line RI - 24 $ 0.50 LF Page 4 of 9 "KCC 27A authorizes only one bond reduction. KC Bond Quantity W orksheet 2020-09 SUBTOTAL 14,131.75 75,154.00 Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 9/1/2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Right-of-way Future Public Right of Way & Drainage Facilities Private Improvements Unit Price Unit Quart. Cost Quant. Cost Quant. Cost ROAD SURFACING No. 4" Rock = 2.5 base & 1.5" top course 9 1/2" Rock= 8" base & 1.5" top course Additional 2.5' Crushed Surfacing RS - 1 $ 3.60 SY HMA 1/2" Overlay, 1.5" RS - 2 $ 14.00 SY HMA 1/2" Overlay 2" RS - 3 $ 18.00 SY HMA Road, 2", 4" rock, First 2500 SY RS - 4 $ 28.00 SY 42 1,176.00 HMA Road, 2", 4" rock, Qty. over 2500 SY RS - 5 $ 21.00 SY HMA Road, 3", 9 1/2" Rock, First 2500 S RS - 6 $ 42.00 SY HMA Road, 3", 9 1/2" Rock, Qty Over 250 RS - 7 $ 35.00 SY Not Used RS - 8 Not Used RS - 9 HMA Road, 6" Depth, First 2500 SY RS - 10 $ 33.10 SY HMA Road, 6" Depth, Qty. Over 2500 SY RS - 11 $ 30.00 SY HMA 3/4" or 1", 4" Depth RS - 12 $ 20.00 SY Gravel Road, 4" rock, First 2500 SY RS - 13 $ 15.00 SY Gravel Road, 4" rock, Qty. over 2500 SY RS - 14 $ 10.00 SY PCC Road (Add Under Write -Ins w/Desig RS - 15 Thickened Edge IRS - 17 $ 8.60 1 LF Page 5 of 9 "KCC 27A authorizes only one bond reduction. KC Bond Quantity W orksheet 2020-09 SUBTOTAL 1,176.00 Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 9/1/2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Right-of-way Future Public Right of Way & Drainage Facilities Private Improvements Unit Price Unit Quant. Cost Quant. I Cost Quant. Cost DRAINAGE (CPP = Corrugated Plastic Pipe, N12 or Equivalent) For Culvert prices, Average of 4' cover was assumed. Assume perforated PVC is same price as solid pipe. Access Road, R/D D - 1 $ 21.00 1 SY Bollards - fixed D - 2 $ 240.74 1 Each I 1 1 41 962.96 Bollards - removable D - 3 $ 452.34 1 Each * (CBs include frame and lid) CB Type I D - 4 $ 1,500.00 Each CB Type IL D - 5 $ 1,750.00 Each CB Type II, 48" diameter D - 6 $ 2,300.00 Each 1 2,300.00 for additional depth over 4' D - 7 $ 480.00 FT 2 960.00 CB Type II, 54" diameter D - 8 $ 2,500.00 Each for additional depth over 4' D - 9 $ 495.00 FT CB Type II, 60" diameter D - 10 $ 2,800.00 Each for additional depth over 4' 11 $ 600.00 FT CB Type II, 72" diameter -D- D - 12 $ 3,600.00 Each for additional depth over 4' 13 $ 850.00 FT Through -curb Inlet Framework (Add) -D- D - 14 $ 400.00 Each Cleanout, PVC, 4" D - 15 $ 150.00 Each 10 1,500.00 Cleanout, PVC, 6" D - 16 $ 170.00 Each 9 1,530.00 Cleanout, PVC, 8" D - 17 $ 200.00 Each Culvert, PVC, 4" D - 18 $ 10.00 LF 115 1,150.00 Culvert, PVC, 6" D - 19 $ 13.00 LF 465 6,045.00 Culvert, PVC, 8" D - 20 $ 15.00 LF Culvert, PVC, 12" D - 21 $ 23.00 LF Culvert, CMP, 8" D - 22 $ 19.00 LF Culvert, CMP, 12" D - 23 $ 29.00 LF Culvert, CMP, 15" D - 24 $ 35.00 LF Culvert, CMP, 18" D - 25 $ 41.00 LF Culvert, CMP, 24" D - 26 $ 56.00 LF Culvert, CMP, 30" D - 27 $ 78.00 LF Culvert, CMP, 36" D - 28 $ 130.00 LF Culvert, CMP, 48" D - 29 $ 190.00 LF Culvert, CMP, 60" D - 30 $ 270.00 LF Culvert, CMP, 72" D - 31 $ 350.00 LF Page 6 of 9 *KCC 27A authorizes only one bond reduction. KC Bond Quantity W orksheet 2020-09 SUBTOTAL 14,447.96 Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 9/1/2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 DRAINAGE CONTINUED Existing Right-of-way Future Public Right of Way & Drainage Facilities Private Improvements No. Unit Price Unit Quant. Cost Quant. Cost Quant. Cost Culvert, Concrete, 8" D - 32 $ 25.00 LF Culvert, Concrete, 12" D - 33 $ 36.00 LF Culvert, Concrete, 15" D - 34 $ 42.00 LF Culvert, Concrete, 18" D - 35 $ 48.00 LF Culvert, Concrete, 24" D - 36 $ 78.00 LF Culvert, Concrete, 30" D - 37 $ 125.00 LF Culvert, Concrete, 36" D - 38 $ 150.00 LF Culvert, Concrete, 42" D - 39 $ 175.00 LF Culvert, Concrete, 48" D - 40 $ 205.00 LF Culvert, CPP, 6" D - 41 $ 14.00 LF Culvert, CPP, 8" D - 42 $ 16.00 LF Culvert, CPP, 12" D - 43 $ 24.00 LF Culvert, CPP, 15" D - 44 $ 35.00 LF Culvert, CPP, 18" D - 45 $ 41.00 LF Culvert, CPP, 24" D - 46 $ 56.00 LF Culvert, CPP, 30" D - 47 $ 78.00 LF Culvert, CPP, 36" D - 48 $ 130.00 LF Ditching D - 49 $ 9.50 CY Flow Dispersal Trench (1,436 base+) D - 50 $ 28.00 LF French Drain (3' depth) D - 51 $ 26.00 LF Geotextile, laid in trench, polypropylene D - 52 $ 3.00 SY Mid -tank Access Riser, 48" dia, 6' deep D - 54 $ 2,000.00 Each Pond Overflow Spillway D - 55 $ 16.00 SY Restrictor/Oil Separator, 12" D - 56 $ 1,150.00 Each Restrictor/Oil Separator, 15" D - 57 $ 1,350.00 Each Restrictor/Oil Separator, 18" D - 58 $ 1,700.00 Each Riprap, placed D - 59 $ 42.00 CY Tank End Reducer (36" diameter) D - 60 $ 1,200.00 Each Trash Rack, 12" D - 61 $ 350.00 Each Trash Rack, 15" D - 62 $ 410.00 Each Trash Rack, 18" 1 D - 63 $ 480.00 Each Trash Rack, 21" 1 D - 64 $ 550.00 Each Page 7 of 9 *KCC 27A authorizes only one bond reduction. KC Bond Quantity W orksheet 2020-09 SUBTOTAL Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 9/1/2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Existing Right-of-way Future Public Right of Way & Drainage Facilities Private Improvements Unit Price Unit Quant. Price Quant. I Cost Quant. Cost PARKING LOT SURFACING Not To Be Used For Roads Or Shoulders No. 2" AC, 2" top course rock & 4" borrow PL - 1 $ 21.00 SY NA NA 148 3108 2" AC, 1.5" top course & 2.5" base cours PL - 2 $ 28.00 SY NA NA 4" select borrow PL - 3 $ 5.00 SY NA NA 1.5" top course rock & 2.5" base course PL - 4 $ 14.00 SY NA NA UTILITY POLES & STREET LIGHTING Utility pole relocation costs must be accompanied by Franchise Utility's Cost Estimate Utility Pole(s) Relocation UP-1 Lump Sum Street Light Poles w/Luminaires UP-2 $ 7,500.00 Each WRITE -IN -ITEMS (Such as detention/water quality vaults.) No. Stormwater Vault W I - 1 $ 20.00 CF 4368 87,360.00 Block Wall WI-2 $ 16.00 SY 145 2,320.00 Yard Drain WI-3 $ 225.00 CY 2 450.00 Trench Drain WI-4 $ 50.00 LF 136 6,800.00 Flow Control Sturcture WI-5 $ 700.00 EA 1 700.00 Pump System WI - 6 $ 1,500.00 EA 1 1,500.00 WI-7 WI-8 WI-9 wi-to SUBTOTAL SUBTOTAL (SUM ALL PAGES): 30%CONTINGENCY & MOBILIZATION: GRANDTOTAL: COLUMN: Page 8 of 9 "KCC 27A authorizes only one bond reduction. KC Bond Quantity W orksheet 2020-09 15, 307.75 4,592.33 ..11 W. B C D 192,689.96 57,806.99 250,496.95 Unit prices updated: 03/02/2015 Version: 03/02/2015 Report Date: 9/1/2020 Site Improvement Bond Quantity Worksheet Web date: 04/03/2015 Original bond computations prepared by: Name: PE Registration Number: Firm Name: LPD Engineering PLLC Address: 1932 First Avenue, Suite 201, Seattle WA 98101 Project No: Stabilization/Erosion Sediment Control (ESC) Existing Right -of -Way Improvements Future Public Right of Way & Drainage Facilities Private Improvements Calculated Quantity Completed Total Right -of Way and/or Site Restoration Bond*/** (First $7,500 of bond* shall be cash. Performance Bond* Amount (A+B+C+D) = TOTAL Maintenance/Defect Bond* Total NAME OF PERSON PREPARING BOND* REDUCTION: Date: 4/22/2019 Tel. #: 206-725-1211 FINANCIAL GUARANTEE REQUIREMENTS PERFORMANCE BOND* AMOUNT (A) $ 7,832.5 (B) $ 19,900.1 (C) $ - (D) $ 250,496.9 (A+B) $ 27,732.6 (T) $ 278,229.5 Minimum is $2000. MINIMUM BOND* AMOUNT REQUIRED FOR RECORDING OR TEMPORARY OCCUPANCY AT SUBSTANTIAL COMPLETION *** T x 0.30 $ 83,468.9 Minimum is $2000. Date: PUBLIC ROAD & DRAINAGE MAINTENANCE/DEFECT BOND* (B+C) x 0.25 = $ 4,975.0 Minimum is $2000. * NOTE: The word "bond" as used in this document means a financial guarantee acceptable to King County. ** NOTE: KCC 27A authorizes right of way and site restoration bonds to be combined when both are required. The restoration requirement shall include the total cost for all TESC as a minimum, not a maximum. In addition, corrective work, both on- and off -site needs to be included. Quantities shall reflect worse case scenarios not just minimum requirements. For example, if a salmonid stream may be damaged, some estimated costs for restoration needs to be reflected in this amount. The 30% contingency and mobilization costs are computed in this quantity. *** NOTE: Per KCC 27A, total bond amounts remaining after reduction shall not be less than 30% of the original amount (T) or as revised by major design changes. REQUIRED BOND* AMOUNTS ARE SUBJECT TO REVIEW AND MODIFICATION BY KING COUNTY Page 9 of 9 Unit prices updated: 03/02/2015 Check out the DDES Web site at www.kingcounty.goy/permits Version: 03/02/2015 KC Bond Quantity Worksheet 2020-09 Report Date: 9/1/2020