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APPROVED STM RESUB2 BLD2021-1384+Storm_Drainage_Report+4.1.2022_4.13.07_PM+2777230Ccivil & structural ENGINEERING engineering & planning BLD2021-1384 RESUB Apr 03 2022 CITY OF EDMONDS DEVELOPMENT SERVICES DEPARTMENT DRAINAGE REPORT Port of Edmonds Admin Building REVIEWED BY CITY OF EDMONDS 250 4ch Ave S Ste 200 Edmonds, WA 98020 Phone: (425) 778-8500 Fax: (425) 778-5536 471 Admiral Way Edmonds, WA 98020 0410112022 CG Project No.: 21160.20 COMPLIES WITH APPLICABLE CITY STO/RMWATER CODE ( �C� 05/04/2022 Table of Contents Section I — Project Overview Section II — Off -Site Analysis Section III — Permanent Stormwater Control Plan Section IV — Construction Stormwater Pollution Prevention Plan Section V — Special Reports and/or Studies Section VI — Other Permits Section VII — Bond Quantities & Operation and Maintenance Manual 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section I, Page 1 Section I — Proiect Overview Section I Summary Overview Existing Condition Developed Condition Minimum Requirements nupruiplA/ This drainage report has been written for a new building on a 4.34 ac lot located at 471 Admiral Way in Edmonds, WA (TPN: 27032300415800). The building will have a roof area of approximately 7,294 sf (0.17 ac) and the project's area of disturbance will total approximately 0.52 ac. The development also consists of a driveway, parking spaces, and sidewalk improvements along Admiral Way. The site is currently developed with asphalt and gravel surfaces used mostly for car parking and storage areas. The project will meet minimum requirements 1 through 9 of the 2014 Department of Ecology Stormwater Management Manual for Western Washington (herein referred to as the DOE Manual) and comply with those requirements as modified in the Edmonds Community Development Code Chapter 18.30 (herein referred to as ECDC 18.30) and the December 2016 Addendum to ECDC 18.30 (herein referred to as the Edmonds Stormwater Addendum). Existing Condition The site is part of a 4.34-acre parcel which is elongated with the longer side being aligned parallel with Admiral Way. The area of work is located towards the southwestern end of the parcel and contains gravel and asphalt parking and gravel storage area. The site soils primarily consist of medium dense, moist fill soils extending to about 8' below grade. The top of the groundwater table was located at 9' below grade during the time of the testing in early June. The infiltration rate measured is approximately 0.001 in/hr. More about site soils can be found in the Geotechnical Engineering Report by Landau Associates in Section V. The site is located in a seismic hazard area and floodplain. The site is bordered by Admiral Way to the northwest, BNSF Railroad property to the southeast, and boat and car parking areas to the northeast and southwest, respectively. Water and Sewer utilities run along Admiral Way, and there are several catch basins and a storm drain manhole across the street from the site which are conveyed to an outfall in the Puget Sound. Developed Condition The project consists of the construction of a 7,294-sf building along with an associated driveway, parking, walkways, and Right -of -Way (ROW) improvements. The total new plus replaced impervious area (including ROW) is 23,598 sf (0.54 ac). Disturbance will affect 0.52 ac of the project parcel. Site roof runoff will be routed to an existing storm main on Admiral Way. Runoff from other impervious site areas will be directly conveyed to the storm main via catch basins and conveyance pipes. The proposed impervious areas (including ROW) are as follows: 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section I, Page 2 Roof: 7,294 sf (0.17 ac) Sidewalk: 1,221 sf (0.03 ac) Driveway: 12,251 sf (0.28 ac) ROW Sidewalk: 1,934 sf (0.04 ac) ROW Driveway: 898 sf (0.02 ac) Total: 23,598 sf (0.54 ac) The new and replaced pollution -generating impervious areas are as follows: Concrete Trash Area: 231 sf (0.01 ac) Asphalt Driveway: 13,149 sf (0.30 ac) Total: 13,380 sf (0.31 sf) The building roof will not be considered as pollution -generating as the roof will be made with non - leachable material. Total parcel area: 4.34 ac Total hard surfaces: 0.54 ac PGHS/PGIS:0.31 ac Total disturbed area: 0.52 ac UN10/yOIL COMpINrR,) Figure 1-1. Vicinity map (from Edmonds GIS). 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section I, Page 3 7-ly; 0 T O �7-1v2 - --- 7-19 -194 to PROJECT SITE (AREA OF WORK) % Figure 1-2. Map with storm pipe material (from Edmonds GIS). C 4=M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 April 01, 2022 Drainage Report Section I, Page 4 4 Z 1.. Figure 1-3. Aerial Photograph (from Edmonds GIS). Minimum Requirements Stormwater requirements were determined per the Edmonds Stormwater Addendum, ECDC 18.30, and the DOE Manual. This report is based on the steps recommended in Chapter 7 of the Edmonds Stormwater Addendum and Section 3.1.7 of the DOE Manual. The project is classified as a Category 2 because it will result in more than 5,000 sf of new plus replaced hard surfaces. Following the flow chart in Figure 1-4, Minimum Requirements #1-9 will apply to all new and replaced hard surfaces. Minimum Requirement #1: Preparation of Stormwater Site Plans: The stormwater site plan consists of this report and the civil drawings and is prepared in accordance with Chapter 3 of Volume 1 of the DOE Manual and the requirements in the Edmonds Stormwater Addendum. C 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section I, Page 5 Minimum Requirement #2: Construction Stormwater Pollution Prevention Plan (SWPPP): The SWPPP shall include a narrative and drawings. The SWPPP narrative shall include documentation that addresses the 13 elements of Construction Stormwater Pollution Prevention. See Section IV and the civil drawings. Minimum Requirement #3: Source Control of Pollution: All known, available and reasonable source control BMPs must be required for all projects approved by the City. Mandatory Operational Source Control BMPs must be implemented by forming a pollution prevention team, good housekeeping practices, preventive maintenance, spill prevention and cleanup, employee training, inspections, and record keeping. See Section IV for a source control discussion and Section VII for source control guide sheets from the DOE Manual. Minimum Requirement #4: Preservation of Natural Drainage Systems and Outfalls: Natural drainage patterns shall be maintained, and discharges from the project site shall occur at the natural location, to the maximum extent practicable. The manner by which runoff is discharged from the project site must not cause a significant adverse impact to downstream receiving waters and down -gradient properties. All projects shall submit an off -site qualitative analysis. A qualitative analysis of the upstream and downstream system entering the site is presented in Section II. Minimum Requirement #5: On -Site Stormwater Management: The proposed project is classified as a Category 2 per the Edmonds Stormwater Addendum. However, since the site is located in a Puget Sound direct discharge area (per ECDC 18.30.060.D.5.b.iv), the project does not have to achieve the LID Performance Standard, nor consider bioretention, rain gardens, permeable pavement, or full dispersion. The project must evaluate an alternative list of BMPs. This is discussed in Section III. Minimum Requirement #6: Runoff Treatment: This requirement applies to the new plus replaced hard surfaces and the converted vegetated areas that will generate pollutants and be conveyed to the public storm system through stormwater runoff. Runoff treatment is required because the project will result more than 5,000 sf of pollution -generating hard surfaces in a threshold discharge area. This is discussed in Section III. Minimum Requirement #7: Flow Control: Projects must provide flow control to reduce the impacts of stormwater runoff from hard surfaces and land cover conversions. However, flow control is not required for projects that discharge directly to, or indirectly through the City's MS4 to Puget Sound (ECDC 18.30.060.D.7 a). The project site will discharge to the Puget Sound, and Flow Control is not required. Minimum Requirement #8: Wetlands Protection: Not applicable. There are no wetlands located in the immediate downstream vicinity of the site or the outfall into Puget Sound. Minimum Requirement #9: Operation and Maintenance: An operation and maintenance manual that is consistent with the provisions in Volume I and Volume V of the SWMMWW is required for proposed Stormwater Treatment and On -Site Stormwater Management facilities. The party (or parties) responsible 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section I, Page 6 for maintenance and operation shall be identified in the operation and maintenance manual. For private facilities approved by the City, a copy of the operation and maintenance manual shall be retained on -site or within reasonable access to the site and shall be transferred with the property to the owner. For public facilities, a copy of the operation and maintenance manual shall be retained in the appropriate department. A log of maintenance activity that indicates what actions were taken shall be kept and be available for inspection. Does the project result in 2,000 square feet, or greater, of new plus replaced hard surface area? OR Does the land disturbing activity total 7,000 square tcct or greater' yes No Minimum Requirements No. I through 5 apph I Minimum Requirement No. 2 applies Next Question Uocs 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 yes Is this a road related protect' All Minimum Requirements apply to the new and replaced yes hard surfaces and converted vegetation areas. All Minimum Requirements apply to the new hard surfaces and converted vegetation areas. Ten Does the project add 5,000 square feet or more of new hard surfaces? Teo Do new hard surfaces add 50% or more to the existing hard surfaces within the project limits? No NO No No additional rcquucmcnt Figure 1-4. Flow chart for determining requirements for development (Figure 3.1 in the Edmonds Stormwater Addendum). C 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section II, Page 1 Section II — Off -Site Analvsis Section II Summary Task 1— Define and map the study area Task 2 — Review all available information of the study area Task 3 — Field inspect the area Task 4 - Describe the drainage system, and its existing and predicted problems Task 1— Define and map the study area An initial qualitative analysis shall document potential off -site impacts of stormwater discharges for each upstream drainage system entering a site, and each downstream drainage system leaving a site according to Section 6.2 of the Edmonds Stormwater Addendum. The downstream analysis shall extend from the project site to the receiving water, or up to one -quarter mile, whichever is less. Runoff from the site will be conveyed to the existing City storm main on the north side of Admiral Way via catch basins and pipes. The City storm main conveys stormwater northwest for about 445 feet until an outfall into the Puget Sound. The downstream flow path is outlined below in Figure II-1 from the City GIS map. The site is located in the Puget Sound Piped Watershed. NO. ° ° OUTFALL ° 7 193/ ss F7-1 ll \7-312 /ROJECTSMI&* Figure II-1. Vicinity map showing stormwater flow path and distance to outfall (from Edmonds GIS). 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section II, Page 2 Task 2 — Review all available information on the study area Existing stormwater improvements were determined from the survey, the initial site visit, and the City GIS map. Runoff from the site will be conveyed west to a storm manhole on the west side of Admiral Way. The existing manhole has three existing knockouts. It is expected that an additional knockout on the east - facing side of the manhole will be acceptable and maintain 8" separation between knockouts as required per WSDOT Standard Plan B-15.20-01 The 12" concrete main will continue west through the Anthony's Homeport parking lot on the north side of Admiral Way. After about 170 lineal feet, there is a catch basin and the pipe changes to 12" PVC. After about 90 lineal feet, there is a manhole junction, and the outlet is 18" HPDE. The HDPE continues for 75 lineal feet, reaches a catch basin, and changes direction for 40 lineal feet before reaching another manhole. The manhole outlet is noted as an 8" pipe of unknown material, which flows into the Puget Sound in the Edmonds Marina, but this will need to be field verified, as the conveyance system usually would not change to a smaller diameter pipe right before the river. Further research will be done for this prior to future engineering submittals. The system conveys the stormwater around the restaurant and outfalls near the boat launch. Task 3 — Field inspect the study area A site visit was done on the afternoon of March 26, 2021. The weather was partly cloudy. From evaluating surrounding conditions, the site does not appear to take on significant upstream runoff. Pavement from the areas to the north and south of the project site is sloped down and away from the project site. In the proposed condition, a curb will be added to the north edge of the site to prevent any site run on from the north site. The project proposes to tie all roof drains to perforated stub -out connections prior to discharging to storm drain main on the north side of Admiral Way. There was not much to be seen from the off -site walk since the conveyance system consists entirely of underground pipes and manholes. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section II, Page 3 Figure II-2. From the north side of Admiral Way, looking southeast towards the project site. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section 11, Page 4 PrT l r so u A Figure II-3. From the project site frontage, looking northwest towards the storm manhole of proposed connection. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section II, Page 5 Figure II-4. From a downstream catch basin facing northwest towards the outfall. C 4m ENGINEERING 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 April 01, 2022 Drainage Report Section II, Page 6 M Figure II-5. Facing toward the approximate area of the proposed outfall. Task 4 — Describe the drainage system, and its existing and predicted problems The site is in the Puget Sound Piped Watershed. The project proposes to route all runoff from the building to perforated stub -out connections beneath landscaping areas with a discharge to a public storm main on Admiral Way. Runoff from other impervious areas will routed directly to the public storm main, and no stormwater management BMPs are proposed. There are no predicted problems with the drainage system so long as the installation and maintenance of drainage facilities are done properly. C 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section III, Page 1 Section III — Permanent Stormwater Control Plan Section III Summary Narrative Feasibility Review Runoff Treatment Water Quality WWHM Al rn rrrn ti vc This project is classified as a Category 2 per the Edmonds Stormwater Addendum because it results in 5,000 sf or more of new plus replaced hard surfaces. However, since the project is in a Puget Sound direct discharge area, per ECDC 18.30.060.D.5.b.iv, the project does not have to achieve the LID Performance Standard, nor consider bioretention, rain gardens, permeable pavement, or full dispersion. Runoff treatment is required for this project since the project has more than 5,000 sf of Pollution Generating Hard Surfaces (PGHS), and BMPs are addressed below. Sidewalks added in front of the property in the right of way will drain into catch basins in the Admiral Way flow line. They are also considered a portion of the direct discharge basin. Feasibility Review The project must implement on -site stormwater management BM Ps to the maximum extent feasible per Minimum Requirement #5. The following BM Ps were evaluated per ECDC 18.30.060.D.5.b.iv.A for all new plus replaced hard surfaces and land disturbed: 1. Post -Construction Soil Quality & Depth in accordance with BMP T5.13 in Chapter 5 of Volume V of the SWMMWW will be used for all disturbed pervious areas. 2. Downspout Full Infiltration Systems (BMP T5.10A) are infeasible because of the presence of fill soils extending to 8' below grade and a groundwater elevation of 9' below grade (according to the Geotechnical Report by Landau Assoc.). In addition, the infiltration rate on site was measured as 0.001 in/hr.. Often, projects have required anchoring systems for check vaults, grease interceptors, etc. 3. Downspout Dispersion Systems (BMP T5.1013) are infeasible because there is no room on -site for dispersion systems. 4. Perforated Stub -Out Connections (BMP T5.10C) are infeasible due to the presence of groundwater as described above. 5. Concentrated Flow Dispersion (BMP T5.11) and Sheet Flow Dispersion (BMP T5.12) are infeasible because there is no room on -site for dispersion systems. The retrofit requirement is required to be addressed for the project parcel. Per ECDC 18.30.060.D.5.b.1, the retrofit requirement is required to provide on -site stormwater management BMPs to at least 25% of existing unmanaged surfaces on the parcel. Since the entire parcel is also included in the direct discharge 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section III, Page 2 exemption as described in Section I, the same feasibility review applies to unmanaged areas. No BMPs were found to be feasible, and the retrofit requirement does not apply. Runoff Treatment The project PGHS is subject to Enhanced Treatment per the SWMMWW since the site is a Commercial Project Site. See Figure III-1 below for the flow chart used for treatment facility selection. The project will utilize an Emerging Stormwater Treatments Technology (TAPE) for enhanced treatment, specifically, a BioClean Modular Wetland System (MWS). A detail of the MWS is shown below and in the civil plans, and the DOE TAPE approval sheet is included at the end of this Section. A WWHM water quality model was ran to determine the design flow for the system. As shown in the detail and WWHM report and MWS detail, the off-line target flow for a water quality BMP is 0.0278 cfs. The design flow for the proposed MWS-L-4-4-V is 0.0278 cfs. Therefore, the proposed BMP is sufficient for the project application. See below. The building roof will not be considered as pollution -generating as the roof will be made with non - leachable material. Any mechanical equipment on the roof will use internal spill containment for liquids, oils, and other chemicals used in their function as required. Refer to the mechanical plans for more information. Refer to a developed conditions drainage exhibit at the end of this Section for a map which defines site PGHS and areas routed to the water quality system. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com WWHM2012 PROJECT REPORT Project Name: POE Admin Building Water Quality 01.20.22 Site Name: Site Address: City Report Date: 1/20/2022 MGS Regoin Puget East Data Start 1901/10/1 Data End : 2058/09/30 DOT Data Number: 03 Version Date: 2019/09/13 Version : 4.2.17 Low Flow Threshold for POC 1 : 50 Percent of the 2 Year High Flow Threshold for POC 1: 50 year PREDEVELOPED LAND USE Name : Basin 1 Bypass: No Groundwater: No Pervious Land Use acre C, Forest, Flat .42 Pervious Total 0.42 Impervious Land Use acre Impervious Total 0 Basin Total 0.42 Element Flows To: Surface Interflow MITIGATED LAND USE Name : Basin 1 Bypass: No GroundWater: No Groundwater Pervious Land Use acre C, Lawn, Flat .03 Pervious Total 0.03 Impervious Land Use acre DRIVEWAYS FLAT 0.32 SIDEWALKS FLAT 0.07 Impervious Total 0.39 Basin Total 0.42 Element Flows To: Surface Interflow Groundwater ANALYSIS RESULTS Stream Protection Duration Predeveloped Landuse Totals for POC #1 Total Pervious Area:0.42 Total Impervious Area:O Mitigated Landuse Totals for POC #1 Total Pervious Area:0.03 Total Impervious Area:0.39 Flow Frequency Return Periods for Predeveloped. POC #1 Return Period Flow(cfs) 2 year 0.006992 5 year 0.01149 10 year 0.014025 25 year 0.016658 50 year 0.018245 100 year 0.019562 Flow Frequency Return Periods for Mitigated. POC #1 Return Period Flow(cfs) 2 year 0.098027 5 year 0.129688 10 year 0.152444 25 year 0.183308 50 year 0.207883 100 year 0.233854 Stream Protection Duration Annual Peaks for Predeveloped and Mitigated. POC #1 Year Predeveloped Mitigated 1902 0.010 0.108 1903 0.003 0.121 1904 0.007 0.139 1905 0.004 0.064 1906 0.001 0.072 1907 0.011 0.099 1908 0.007 0.087 1909 0.007 0.111 1910 0.012 0.101 1911 0.006 0.105 1912 0.025 0.177 1913 0.010 0.064 1914 0.002 0.252 1915 0.003 0.067 1916 0.006 0.106 1917 0.003 0.066 1918 0.007 0.097 1919 0.005 0.057 1920 0.006 0.085 1921 0.007 0.063 1922 0.007 0.086 1923 0.006 0.091 1924 0.003 0.116 1925 0.003 0.064 1926 0.006 0.122 1927 0.008 0.088 1928 0.005 0.081 1929 0.012 0.134 1930 0.007 0.151 1931 0.006 0.069 1932 0.005 0.081 1933 0.005 0.076 1934 0.016 0.121 1935 0.006 0.072 1936 0.009 0.078 1937 0.008 0.110 1938 0.007 0.073 1939 0.000 0.101 1940 0.006 0.137 1941 0.006 0.115 1942 0.009 0.108 1943 0.003 0.121 1944 0.008 0.179 1945 0.007 0.120 1946 0.006 0.084 1947 0.004 0.077 1948 0.014 0.098 1949 0.012 0.157 1950 0.006 0.066 1951 0.008 0.103 1952 0.023 0.172 1953 0.018 0.166 1954 0.005 0.087 1955 0.005 0.075 1956 0.003 0.059 1957 0.008 0.086 1958 0.020 0.108 1959 0.012 0.103 1960 0.004 0.084 1961 0.012 0.240 1962 0.006 0.094 1963 0.003 0.065 1964 0.004 0.173 1965 0.014 0.104 1966 0.003 0.078 1967 0.005 0.088 1968 0.007 0.079 1969 0.005 0.088 1970 0.008 0.104 1971 0.015 0.108 1972 0.010 0.315 1973 0.011 0.172 1974 0.007 0.131 1975 0.016 0.152 1976 0.007 0.130 1977 0.004 0.059 1978 0.014 0.111 1979 0.004 0.100 1980 0.007 0.098 1981 0.007 0.112 1982 0.005 0.081 1983 0.011 0.114 1984 0.003 0.107 1985 0.007 0.104 1986 0.005 0.069 1987 0.011 0.109 1988 0.008 0.073 1989 0.007 0.070 1990 0.008 0.075 1991 0.006 0.121 1992 0.010 0.122 1993 0.008 0.140 1994 0.014 0.092 1995 0.003 0.065 1996 0.016 0.095 1997 0.007 0.079 1998 0.007 0.101 1999 0.000 0.110 2000 0.005 0.111 2001 0.004 0.100 2002 0.012 0.146 2003 0.007 0.076 2004 0.008 0.129 2005 0.011 0.187 2006 0.005 0.082 2007 0.005 0.115 2008 0.007 0.090 2009 0.004 0.085 2010 0.003 0.107 2011 0.004 0.073 2012 0.006 0.109 2013 0.005 0.081 2014 0.003 0.086 2015 0.013 0.152 2016 0.002 0.070 2017 0.012 0.159 2018 0.022 0.107 2019 0.022 0.140 2020 0.007 0.118 2021 0.009 0.110 2022 0.003 0.141 2023 0.008 0.153 2024 0.028 0.210 2025 0.006 0.083 2026 0.011 0.094 2027 0.005 0.111 2028 0.002 0.052 2029 0.008 0.083 2030 0.016 0.127 2031 0.004 0.059 2032 0.003 0.069 2033 0.004 0.074 2034 0.004 0.079 2035 0.017 0.105 2036 0.009 0.075 2037 0.001 0.104 2038 0.010 0.102 2039 0.001 0.164 2040 0.003 0.084 2041 0.005 0.097 2042 0.018 0.116 2043 0.008 0.130 2044 0.011 0.089 2045 0.007 0.083 2046 0.008 0.080 2047 0.005 0.108 2048 0.007 0.090 2049 0.006 0.135 2050 0.004 0.083 2051 0.007 0.138 2052 0.004 0.085 2053 0.007 0.089 2054 0.011 0.140 2055 0.003 0.087 2056 0.003 0.114 2057 0.004 0.069 2058 0.005 0.123 Stream Protection Duration Ranked Annual Peaks for Predeveloped and Mitigated. POC #1 Rank Predeveloped Mitigated 1 0.0277 0.3153 2 0.0250 0.2522 3 0.0232 0.2397 4 0.0224 0.2103 5 0.0217 0.1871 6 0.0197 0.1788 7 0.0183 0.1772 8 0.0180 0.1735 9 0.0172 0.1722 10 0.0164 0.1717 11 0.0162 0.1659 12 0.0159 0.1635 13 0.0156 0.1585 14 0.0151 0.1571 15 0.0145 0.1526 16 0.0143 0.1523 17 0.0142 0.1519 18 0.0136 0.1512 19 0.0127 0.1461 20 0.0122 0.1413 21 0.0119 0.1405 22 0.0119 0.1404 23 0.0118 0.1404 24 0.0118 0.1392 25 0.0116 0.1382 26 0.0115 0.1374 27 0.0114 0.1351 28 0.0113 0.1344 29 0.0111 0.1315 30 0.0110 0.1297 31 0.0108 0.1297 32 0.0108 0.1288 33 0.0107 0.1274 34 0.0105 0.1232 35 0.0104 0.1223 36 0.0098 0.1223 37 0.0097 0.1214 38 0.0096 0.1213 39 0.0095 0.1212 40 0.0094 0.1211 41 0.0092 0.1204 42 0.0091 0.1180 43 0.0088 0.1162 44 0.0085 0.1161 45 0.0084 0.1154 46 0.0083 0.1146 47 0.0082 0.1139 48 0.0081 0.1137 49 0.0081 0.1118 50 0.0080 0.1115 51 0.0078 0.1113 52 0.0077 0.1111 53 0.0077 0.1108 54 0.0077 0.1100 55 0.0077 0.1097 56 0.0076 0.1096 57 0.0075 0.1090 58 0.0075 0.1088 59 0.0075 0.1085 60 0.0075 0.1079 61 0.0074 0.1079 9080'0 bb00'0 8TT 9080' 0 SH0' 0 LTT TT80'0 9b00'0 9TT 9T8O'O 9b00'0 STT LZ80'0 9b00'0 ITT 6Z80'0 9b00'0 £TT 0£80'0 Lb00'0 ZTT T£80'0 Lb00'0 TTT 9£80'0 6b00'0 OTT T�80'0 OS00'O 60T bb80'0 0900'0 80T 0980'0 T900'0 LOT £980'0 T900'0 90T SS80'0 £S00'O SOT LS80'0 £S00'O bOT 0980'0 P900'0 £OT T980'0 PS00'0 ZOT 8980'0 PS00'0 TOT 8980'0 b900'0 OOT TL80'0 b900'0 66 9L80'0 9900'0 86 LL80'0 LS00'0 L6 T880'0 LS00'0 96 S880'0 8900'0 S6 b680'0 6S00'O b6 0060'0 0900'0 £6 £060'0 0900'0 Z6 OT60'0 0900'0 T6 TZ60'0 T900'O 06 L£60'0 T900'O 68 Tb60'0 Z900'0 88 9960'0 £900'0 L8 9960'0 b900'0 98 OL60'0 S900'0 S8 8L60'0 S900'0 b8 Z860'0 9900'0 £8 T660'0 9900'0 Z8 6660'0 9900'0 T8 £OOT'O S900'0 08 600T'0 9900'0 6L OTOT'0 9900'0 8L £TOT'0 9900'0 LL TZOT'0 L900'0 9L LZOT'0 8900'0 SL 6ZOT'0 8900'0 bL 6£OT'0 8900'0 £L O�OT'0 8900'0 ZL ZbOT'0 6900'0 TL PPOT'0 6900'0 OL OSOT'0 6900'0 69 SSOT'0 OL00'0 89 LSOT'0 OL00'0 L9 890T'0 TL00'0 99 TLOT'0 ZL00'0 99 TLOT'0 ZL00'0 b9 9LOT'0 £L00'0 £9 SLOT'O £L00'O Z9 119 0.0044 0.0806 120 0.0044 0.0798 121 0.0043 0.0794 122 0.0042 0.0793 123 0.0042 0.0785 124 0.0041 0.0781 125 0.0041 0.0780 126 0.0041 0.0774 127 0.0040 0.0762 128 0.0038 0.0761 129 0.0036 0.0754 130 0.0036 0.0747 131 0.0036 0.0747 132 0.0035 0.0740 133 0.0034 0.0731 134 0.0034 0.0730 135 0.0034 0.0728 136 0.0033 0.0722 137 0.0032 0.0722 138 0.0032 0.0697 139 0.0032 0.0697 140 0.0031 0.0693 141 0.0031 0.0691 142 0.0030 0.0688 143 0.0029 0.0688 144 0.0029 0.0670 145 0.0027 0.0661 146 0.0027 0.0656 147 0.0027 0.0652 148 0.0027 0.0646 149 0.0025 0.0642 150 0.0024 0.0636 151 0.0023 0.0636 152 0.0019 0.0628 153 0.0015 0.0594 154 0.0014 0.0588 155 0.0006 0.0588 156 0.0004 0.0573 157 0.0001 0.0517 The development has an increase in flow durations from 1/2 Predeveloped 2 year flow to the 2 year flow or more than a 10% increase from the 2 year to the 50 year flow. The development has an increase in flow durations for more than 500 of the flows for the range of the duration analysis. Water Quality BMP Flow and Volume for POC #1 On-line facility volume: 0.036 acre-feet On-line facility target flow: 0.0491 cfs. Adjusted for 15 min: 0.0551 cfs. Off-line facility target flow: 0.0278 cfs. Adjusted for 15 min: 0.0311 cfs. LID Report LID Technique Used for Total Volume Percent Water Quality Percent Comment Treatment? Needs Volume Water Quality Treatment Infiltrated Treated (ac-£t) Total Volume Infiltrated 0.00 0.00 0% No Treat. Credit Compliance with LID Standard 8 Duration Analysis Result = Failed Perind and Impind Changes No changes have been made. Volume Infiltration Cumulative Through Volume Volume Facility (ac-ft.) Infiltration (ac-ft) Credit 0.00 0.00 0.00 This program and accompanying documentation are provided 'as -is' without warranty of any kind. The entire risk regarding the performance and results of this program is assumed by End User. Clear Creek Solutions Inc. and the governmental licensee or sublicensees disclaim all warranties, either expressed or implied, including but not limited to implied warranties of program and accompanying documentation. In no event shall Clear Creek Solutions Inc. be liable for any damages whatsoever (including without limitation to damages for loss of business profits, loss of business information, business interruption, and the like) arising out of the use of, or inability to use this program even if Clear Creek Solutions Inc. or their authorized representatives have been advised of the possibility of such damages. Software Copyright © by : Clear Creek Solutions, Inc. 2005-2022; All Rights Reserved. Developed Conditions Drainage Exhibit LP I Lj CONCRETE G _ �SPHALI --- S � 2 _ O �,,-TELE. BOX ASPHALT I G* G* G* SS SS SS ' SS ; ; ' SGO.08 ac—Ss \ SS-- SS ' ' SS— Aw I I ANTHONY PARKING GUEST SIGN ADMIRAL WAY W* I W* I I I IAN -___----- ------J-JaQ�----�--- - - - - - - - 2 ___ ILI LEI] Li — F I CONCRETE -- O co I F O 16 ...�� J � — 1 0.0 "ac lei W-r, D - G* ASPHALT s 5 16 -- UTII 0.04 ac 5. TRE�J � I � J---4-3 5ac 0.16 ac Ln ° a 0.03 ac 1 0',D J / 4. s RECYCLE AREA yFn WA WA— A WA WA W WA WA n_nA aC - 0.8J 1.5%, 2. ■II �III�II �I` �lOIOO,� TYP � 0 o ¢� .13 ac 0 RIM= 6" P 12" C, 12"C( Areas legend On -site area to WQ (includes non -PG) On -site non-PGHS bypass On -site PGHS bypass Off -site to proposed CB-5 Off -site to existing CB-6, CB-7 6' CHAINLINK WASH IX 6T9h STALE ICPABIMEHI 0f ECOLOGY August 2021 GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS) ENHANCED AND PHOSPHORUS TREATMENT For MWS-Linear Modular Wetland Ecology's Decision Based on Modular Wetland Systems, Inc, application submissions, including the Technical Evaluation Report, dated April 1, 2014, Ecology hereby issues the following use level designation: 1. General Use Level Designation (GULD) for the MWS-Linear Modular Wetland Stormwater Treatment System for Basic, Phosphorus, and Enhanced treatment • Sized at a hydraulic loading rate of: • 1 gallon per minute (gpm) per square foot (sq ft) of Wetland Cell Surface Area • Prefilter box (approved at either 22 inches or 33 inches tall) • 3.0 gpm/sq ft of prefilter box surface area for moderate pollutant loading rates (low to medium density residential basins). 2.1 gpm/sq ft of prefilter box surface area for high pollutant loading rates (commercial and industrial basins). 2. Ecology approves the MWS — Linear Modular Wetland Stormwater Treatment System units for Basic, Phosphorus, and Enhanced treatment at the hydraulic loading rate listed above. Designers shall calculate the water quality design flow rates using the following procedures: • Western Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute water quality treatment design flow rate as calculated using the latest version of the Western Washington Hydrology Model or other Ecology- approved continuous runoff model. • Eastern Washington: For treatment installed upstream of detention or retention, the water quality design flow rate is the peak 15-minute water quality treatment design flow rate as calculated using one of the three methods described in Chapter 2.2.5 of the Stormwater Management Manual for Eastern Washington (SWMMEW) or local manual. • Entire State: For treatment installed downstream of detention, the water quality treatment design flow rate is the full 2-year release rate of the detention facility. 3. These use level designations have no expiration date but may be amended or revoked by Ecology, and are subject to the conditions specified below. Ecology's Conditions of Use Applicants shall comply with the following conditions: 1) Design, assemble, install, operate, and maintain the MWS — Linear Modular Wetland Stormwater Treatment System units, in accordance with Modular Wetland Systems, Inc. applicable manuals and documents and the Ecology Decision. 2) Each site plan must undergo Modular Wetland Systems, Inc. review and approval before site installation. This ensures that site grading and slope are appropriate for use of a MWS — Linear Modular Wetland Stormwater Treatment System unit. 3) MSW — Linear Modular Wetland Stormwater Treatment System media shall conform to the specifications submitted to and approved by Ecology. 4) The applicant tested the MWS — Linear Modular Wetland Stormwater Treatment System with an external bypass weir. This weir limited the depth of water flowing through the media, and therefore the active treatment area, to below the root zone of the plants. This GULD applies to MWS — Linear Modular Wetland Stormwater Treatment Systems whether plants are included in the final product or not. 5) Maintenance: The required maintenance interval for stormwater treatment devices is often dependent upon the degree of pollutant loading from a particular drainage basin. Therefore, Ecology does not endorse or recommend a "one size fits all" maintenance cycle for a particular model/size of stormwater treatment technology. • Typically, Modular Wetland Systems, Inc. designs MWS — Linear Modular Wetland systems for a target prefilter media life of 6 to 12 months. • Indications of the need for maintenance include effluent flow decreasing to below the design flow rate or decrease in treatment below required levels. • Owners/operators must inspect MWS — Linear Modular Wetland systems for a minimum of twelve months from the start of post -construction operation to determine site -specific maintenance schedules and requirements. You must conduct inspections monthly during the wet season, and every other month during the dry season (According to the SWMMWW, the wet season in western Washington is October 1 to April 30. According to the SWMMEW, the wet season in eastern Washington is October 1 to June 30). After the first year of operation, owners/operators must conduct inspections based on the findings during the first year of inspections. • Conduct inspections by qualified personnel, follow manufacturer's guidelines, and use methods capable fo determining either a decrease in treated effluent flowrate and/or a decrease in pollutant removal ability. • When inspections are performed, the following findings typically serve as maintenance triggers: • Standing water remains in the vault between rain events, or • Bypass occurs during storms smaller than the design storm. • If excessive floatables (trash and debris) are present (but no standing water or excessive sedimentation), perform a minor maintenance consisting of gross solids removal, not prefilter media replacement. • Additional data collection will be used to create a correlation between pretreatment chamber sediment depth and pre -filter clogging (see Issues to be Addressed by the Company section below) 6) Discharges from the MWS — Linear Modular Wetland Stormwater Treatment System units shall not cause or contribute to water quality standards violations in receiving waters. Applicant: Modular Wetland Systems, Inc. Applicant's Address: 5796 Armada Drive, Suite 250 Carlsbad, CA 92008 Application Documents: Original Application for Conditional Use Level Designation, Modular Wetland System, Linear Stormwater Filtration System Modular Wetland Systems, Inc., January 2011 Quality Assurance Project Plan: Modular Wetland System — Linear Treatment System Performance Monitoring Project, draft, January 2011 Revised Application for Conditional Use Level Designation, Modular Wetland System, Linear Stormwater Filtration System Modular Wetland Systems, Inc., May 2011 Memorandum: Modular Wetland System -Linear GULD Application Supplementary Data, April 2014 Technical Evaluation Report: Modular Wetland System Stormwater Treatment System Performance Monitoring, April 2014 Applicant's Use Level Request: • General Use Level Designation as a Basic, Enhanced, and Phosphorus treatment device in accordance with Ecology's Guidance for Evaluating Emerging Stormwater Treatment Technologies Technology Assessment Protocol — Ecology (TAPE) January 2011 Revision. Applicant's Performance Claims: • The MWS — Linear Modular wetland is capable of removing a minimum of 80-percent of TSS from stormwater with influent concentrations between 100 and 200 mg/L. • The MWS — Linear Modular wetland is capable of removing a minimum of 50-percent of total phosphorus from stormwater with influent concentrations between 0.1 and 0.5 mg/L. • The MWS — Linear Modular wetland is capable of removing a minimum 30-percent of dissolved copper from stormwater with influent concentrations between 0.005 and 0.020 mg/L. • The MWS — Linear Modular wetland is capable of removing a minimum 60-percent of dissolved zinc from stormwater with influent concentrations between 0.02 and 0.30 mg/L. Ecology's Recommendations: • Modular Wetland System, Inc. has shown Ecology, through laboratory and field- testing, that the MWS — Linear Modular Wetland Stormwater Treatment System filter system is capable of attaining Ecology's Basic, Phosphorus, and Enhanced treatment goals. Findings of Fact: Laboratory Testing The MWS-Linear Modular wetland has the: • Capability to remove 99 percent of total suspended solids (using Sil-Co-Sil 106) in a quarter -scale model with influent concentrations of 270 mg/L. • Capability to remove 91 percent of total suspended solids (using Sil-Co-Sil 106) in laboratory conditions with influent concentrations of 84.6 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 93 percent of dissolved Copper in a quarter -scale model with influent concentrations of 0.757 mg/L. • Capability to remove 79 percent of dissolved Copper in laboratory conditions with influent concentrations of 0.567 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 80.5-percent of dissolved Zinc in a quarter -scale model with influent concentrations of 0.95 mg/L at a flow rate of 3.0 gpm per square foot of media. • Capability to remove 78-percent of dissolved Zinc in laboratory conditions with influent concentrations of 0.75 mg/L at a flow rate of 3.0 gpm per square foot of media. Field Testing Modular Wetland Systems, Inc. conducted monitoring of an MWS-Linear (Model # MWS-L-4-13) from April 2012 through May 2013, at a transportation maintenance facility in Portland, Oregon. The manufacturer collected flow -weighted composite samples of the system's influent and effluent during 28 separate storm events. The system treated approximately 75 percent of the runoff from 53.5 inches of rainfall during the monitoring period. The applicant sized the system at 1 gpm/sq ft. (wetland media) and 3gpm/sq ft. (prefilter). • Influent TSS concentrations for qualifying sampled storm events ranged from 20 to 339 mg/L. Average TSS removal for influent concentrations greater than 100 mg/L (n=7) averaged 85 percent. For influent concentrations in the range of 20-100 mg/L (n=18), the upper 95 percent confidence interval about the mean effluent concentration was 12.8 mg/L. • Total phosphorus removal for 17 events with influent TP concentrations in the range of 0.1 to 0.5 mg/L averaged 65 percent. A bootstrap estimate of the lower 95 percent confidence limit (LCL95) of the mean total phosphorus reduction was 58 percent. The lower 95 percent confidence limit of the mean percent removal was 60.5 percent for dissolved zinc for influent concentrations in the range of 0.02 to 0.3 mg/L (n=11). The lower 95 percent confidence limit of the mean percent removal was 32.5 percent for dissolved copper for influent concentrations in the range of 0.005 to 0.02 mg/L (n=14) at flow rates up to 28 gpm (design flow rate 41 gpm). Laboratory test data augmented the data set, showing dissolved copper removal at the design flow rate of 41 gpm (93 percent reduction in influent dissolved copper of 0.757 mg/L). Issues to be addressed by the Company: 1. Modular Wetland Systems, Inc. should collect maintenance and inspection data for the first year on all installations in the Northwest in order to assess standard maintenance requirements for various land uses in the region. Modular Wetland Systems, Inc. should use these data to establish required maintenance cycles. 2. Modular Wetland Systems, Inc. should collect pre-treatment chamber sediment depth data for the first year of operation for all installations in the Northwest. Modular Wetland Systems, Inc. will use these data to create a correlation between sediment depth and pre -filter clogging. Technology Description: Download at http://www.modularwetlands.com/ Contact Information: Applicant: Zach Kent BioClean A Forterra Company 5796 Armada Drive, Suite 250 Carlsbad, CA 92008 zach.kent@forteffabp.com Applicant website: http://www.modularwetlands.com/ Ecology web link: http://www.ecy.wa.goy/programs/wWstortnwater/newtech/index.html Ecology: Douglas C. Howie, P.E. Department of Ecology Water Quality Program (360) 870-0983 dou2las.howie@ecy.wa. gov Revision History Date Revision June 2011 Original use -level -designation document September 2012 Revised dates for TER and expiration January 2013 Modified Design Storm Description, added Revision Table, added maintenance discussion, modified format in accordance with Ecology standard December 2013 Updated name of Applicant April 2014 Approved GULD designation for Basic, Phosphorus, and Enhanced treatment December 2015 Updated GULD to document the acceptance of MWS — Linear Modular Wetland installations with or without the inclusion of plants July 2017 Revised Manufacturer Contact Information (name, address, and email) December 2019 Revised Manufacturer Contact Address July 2021 Added additional prefilter sized at 33 inches August 2021 Changed "Prefilter" to "Prefilter box" Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section I11, Page 3 Apply Pretreatment • Preseltling Basin • Any Basic Treatment BMP • Emerging Tech. Apply Infiltration • Infiltration Basin • Infiltration Trench • Bioretention Stop 1: Identify Pollutants of Concern and Perform Off-sde Analysis to Determine Receiving Waters Step 2: Determine if an Oil Control Facility is Required No F top 3: Determine if Ves filtration for ollutant Removal is racticable Ves Apply Oil Control Facility • API Separator • CID Separator • Linear Sand Fitter • Emerging Tech. No Step 4: Determine if Ves Phosphorus Control is Required No 5: Determine if Required No Step 6: Apply a Basic Treatment Facility • Biof ltration Swales • Filer Strip • Basic Wetpond • Wetvault • Treatment Wetlands • Combined Detentiorv`Wetpool • Sand Fitters • Broretention • Media Filter Drain • Emerging Tech. Yes Apply Phosphorus Control Faculty • Large Sand Fitter • Large Wetpond' • Media Filter • Two Facility Treatment Train • Emerging Tech.' • Large Sand Filter • Treatment Wetland • Compost -amended Vegetated Filer Strip • Two Facility Treatment Train • Bioretention • Media Filter Drain • Emerging Tech. When Phosphorus Control and Enhanced treatment are required, the Large Wetpond and certain types of emerging technologies will not meet both types of treatment requirements. A different or an additional treatment facility will be required to meet Enhanced treatment. Figure V-2.1.1 qW Treatment Facility Selection Flow Chart DEPARTMENT OF Revised December 2015 ECOLOGYplease see httpjmww.ecy.wa.govlcopynght_html fa copyright notice induding permissions, State of Washington limitation of liability, and disclaimer. Figure III-1. DOE Treatment Facility Selection Flow Chart. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section IV, Page 1 Section IV — Construction Stormwater Pollution Prevention Plan Section IV Summary: Narrative Erosion control details are provided consistent with the City of Edmonds guidelines. Erosion control plan sheets are provided in full-size as a part of the civil drawing set. For sites under one acre in area, the Department of Ecology (DOE) does not require completion of the full Construction SWPPP or the Construction Stormwater General Permit. Therefore, a Construction SWPPP is not required for this site. The following is an abbreviated format of the SWPPP that addresses each of the 13 elements of construction pollution prevention for the City review. Please note that the project may apply for a DOE permit regardless due to the contaminated soil considerations. Element 1: Mark clearing limits To protect adjacent properties and to reduce the area of soil exposed to construction, the limits of construction will be clearly marked before land -disturbing activities begin. Clearing limits will be to the extents of necessary land disturbance for the new building and this can be seen on drawing sheet C2.1. The BMPs relevant to marking the clearing limits that will be applied for this project include: High Visibility Plastic or Metal Fence (BMP C103) Element 2: Establish construction access Construction access or activities occurring on unpaved areas shall be minimized, yet where necessary, access points shall be stabilized to minimize the tracking of sediment onto public roads. A stabilized construction entrance should be utilized as needed when possible to prevent sediment tracking. See C2.1 for placement. The BMPs relevant to establishing construction access that will be applied for this project include: Stabilized Construction Entrance (BMP C105) Element 3: Control Flow Rates The site slopes on average about 1% from north to south. The site is small enough that a silt fence used for Element 4 may be used to control flow rates. Element 4: Install sediment controls All stormwater runoff from disturbed areas shall pass through an appropriate sediment removal BMP before leaving the construction site or prior to being discharged. Silt fences will be installed on the downstream ends. Pollution prevention facilities on the erosion control plan must be constructed prior to 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section IV, Page 2 or in conjunction with all clearing and grading to ensure that the transport of sediment to surface waters and adjacent properties is minimized. The specific BMPs to be used for controlling sediment on this project include: Silt Fence (BMP C233) Element 5: Stabilize Soils Exposed and unworked soils shall be stabilized with the application of effective BMPs to prevent erosion throughout the life of the project. The specific BMPs for soil stabilization that shall be used on this project include: Temporary and Permanent Seeding (BMP C120) Mulching (BMP C121) Nets and Blankets (BMP C122) Plastic Covering (BMP C123) Sodding (BMP C124) Topsoiling/Composting (BMP C125) Surface Roughening (BMP C130) Dust Control (BMP C140) Element 6: Protect Slopes There are existing surfaces that will be removed as part of the development. Exposed slopes shall be stabilized with BM Ps found in Element 5. Element 7: Protect Drain Inlets Catch basins along Admiral Way and as made operable on -site will be protected from sedimentation. Stormwater shall not enter the conveyance system without first being filtered or treated to remove sediment. Inlet protection devices shall be cleaned or removed and replaced when sediment has filled one-third of the available storage (or as specified by the manufacturer). The specific BMPs to be used for protecting drain inlets are: Storm Drain Inlet Protection (BMP C220) Element 8: Stabilize Channels and Outlets Conveyance channels are not located on or in the immediate vicinity of the site. Element 9: Control Pollutants Design, install, implement and maintain effective pollution prevention measures to minimize the discharge of pollutants. The suggested BMPs are: 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section IV, Page 3 Concrete Handling (BMP C151) Sawcutting and Surfacing Pollution Prevention (BMP C152) Material Delivery, Storage and Containment (BMP C153) For this site, controlling the pollutants will also require strict compliance with the EMMP for the project. Section 10 of the EMMP lists requirements and recommendations for several different construction activities. Element 10: Control Dewatering De -watering is not anticipated, but if needed, should follow the EMMP. Element 11: Maintain BMPs All temporary and permanent erosion and sediment control BMPs shall be maintained and repaired as needed to ensure continued performance of their intended function. Element 12: Manage the Project • Phase development projects to the maximum degree practicable and consider seasonal work limits. • Follow the recommendations and requirements of the EMMP. • Inspection and monitoring — Inspect, maintain, and repair all BMPs as needed to assure continued performance of their intended function. Conduct site inspections and monitoring in accordance with the Construction Stormwater General Permit or local plan approval authority. • Maintain an Updated Construction SWPPP - This SWPPP shall be retained on -site or within reasonable access to the site. - The SWPPP shall be modified whenever there is a change in the design, construction, operation, or maintenance at the construction site that has, or could have, a significant effect on the discharge of pollutants to waters of the state. - The SWPPP shall be modified if, during inspections or investigations conducted by the owner/operator, or the applicable local or state regulatory authority, it is determined that the SWPPP is ineffective in eliminating or significantly minimizing pollutants in stormwater discharges from the site. The SWPPP shall be modified as necessary to include additional or modified BMPs designed to correct problems identified. Revisions to the SWPPP shall be completed within seven (7) days following the inspection. Element 13: Protect Low Impact Development BMPs Low -Impact Development BMPs are not proposed for this project. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section IV, Page 4 Source Controls This project should incorporate required BMPs from Volume IV of the DOE Manual: S407 — BMPs for Dust Control at Disturbed Land Areas and Unpaved Roadways and Parking Lots; S411 — BMPs for Landscaping and Lawn/Vegetation Management; S417 — BMPs for Maintenance of Stormwater Drainage and Treatment Systems; and S424 — BMPs for Roof/Building Drains at Manufacturing and Commercial Buildings. The proposed trash enclosure at the southeast corner of the site shall have dumpsters with operable covers/lids. The catch basin adjacent to the trash enclosure's concrete pad will have a downturn elbow on the downstream pipe to allow for solids removal during maintenance. The Operation & Maintenance Manual found in Section VII contains guide sheets for the aforementioned BMPs. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section V, Page 1 Section V — Special Reports and/or Studies Section V Summary: Narrative The following reports are included in this section: 1. Port of Edmonds Administration and Maintenance Building Geotechnical Engineering Report dated 10/04/2021. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Geotechnical Engineering Report Port Administration and Maintenance Building 471 Admiral Way Edmonds, Washington October 4, 2021 Prepared for Port of Edmonds 336 Admiral Way Edmonds, Washington 98020 LANDAU ASSOCIATES 155 NE 100th St, Ste 302 Seattle, WA 98125 206.631.8680 Landau Associates Geotechnical Engineering Report Port Administration and Maintenance Building 471 Admiral Way Edmonds, Washington This document was prepared by, or under the direct supervision of, the undersigned, whose seal is affixed below. _&AJLV _ Name: Sean Gertz, PE Washington/No. 20100325 Date: October 4, 2021 r .O � 20100315�Q �D.t�S £G1S-fV.V- j SfONAt-b /Zo 21 Document prepared by: - Sean Gertz, PE Project Manager 4 Document reviewed by: L,) Steven R. Wright, PE Quality Reviewer Date: October 4, 2021 Project No.: 0173039.010.011 File path: \\edmdata0l\projects\173\039.010\R\Signature Page.docx Project Coordinator: MCS LANDAU ASSOCIATES Landau Associates TABLE OF CONTENTS Page 1.0 INTRODUCTION ..............................................................................................................................1-1 1.1 Project Description.............................................................................................................1-1 1.2 Scope of Services................................................................................................................1-1 2.0 SITE CONDITIONS...........................................................................................................................2-1 2.1 Geologic Setting..................................................................................................................2-1 2.2 Surface Conditions..............................................................................................................2-1 2.3 Subsurface Explorations.....................................................................................................2-1 2.3.1 Soil Conditions.................................................................................................2-2 2.3.2 Groundwater Conditions..................................................................................2-2 3.0 CONCLUSIONS AND RECOMMENDATIONS....................................................................................3-1 3.1 Seismic Considerations.......................................................................................................3-1 3.1.1 Site Classification and Seismic Design Parameters ...........................................3-1 3.1.2 Liquefaction and Lateral Spreading..................................................................3-1 3.2 Earthwork and Grading......................................................................................................3-2 3.2.1 Site Preparation...............................................................................................3-2 3.2.2 Engineered Fill Materials.................................................................................3-3 3.2.3 Reuse of Site Soils............................................................................................3-3 3.2.4 Wet Weather Earthwork Considerations..........................................................3-4 3.2.5 Subgrade Preparation......................................................................................3-4 3.2.6 Temporary Construction Dewatering...............................................................3-5 3.3 Utility Construction............................................................................................................3-5 3.3.1 Temporary Excavations....................................................................................3-5 3.3.2 Pipe Foundation Support.................................................................................3-6 3.3.3 Pipe Bedding and Trench Backfill.....................................................................3-6 3.4 Flexible Pavement Design...................................................................................................3-7 3.5 Stormwater Infiltration Considerations.............................................................................3-7 3.6 Foundations........................................................................................................................3-8 3.6.1 Rammed Aggregate Piers.................................................................................3-8 3.6.2 Shallow Foundation Support............................................................................3-9 3.6.3 Slab -On -Grade Support..................................................................................3-10 3.6.4 Foundation Settlement..................................................................................3-10 3.6.5 Foundation and Site Drainage........................................................................3-10 3.7 Lateral Earth Pressures on Below -Grade Walls................................................................3-11 4.0 REVIEW OF DOCUMENTS AND CONSTRUCTION OBSERVATIONS .................................................4-1 5.0 USE OF THIS REPORT......................................................................................................................5-1 6.0 REFERENCES ...................................................................................................................................6-1 Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building iii October 4, 2021 Landau Associates FIGURES Figure Title 1 Vicinity Map 2 Site and Exploration Plan TABLES Table Title 1 20181nternational Building Code Seismic Design Parameters 2 Engineered Fill Materials 3 Recommended Soil Parameters for Design of Temporary Shoring APPENDICES Appendix Title A Field Explorations B Laboratory Soil Testing Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building iv October 4, 2021 Landau Associates LIST OF ABBREVIATIONS AND ACRONYMS ACI.......................................................................................American Concrete Institute ASTM.................................................................................................ASTM International bgs................................................................................................. below ground surface ft....................................................................................................................... foot/feet H:V..................................................................................................horizontal to vertical IBC........................................................................................ International Building Code LAI............................................................................................... Landau Associates, Inc. NAVD 88............................................................North American Vertical Datum of 1988 pcf................................................................................................. pounds per cubic foot Port....................................................................................................... Port of Edmonds psf.............................................................................................. pounds per square foot WAC............................................................................ Washington Administrative Code WSDOT............................................... Washington State Department of Transportation Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building v October 4, 2021 Landau Associates This page intentionally left blank. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building vi October 4, 2021 Landau Associates 1.0 INTRODUCTION This report summarizes the results of geotechnical engineering services provided by Landau Associates, Inc. (LAI) in support of the Port of Edmonds (Port; project owner) Administration/Maintenance Building project, located at 471 Admiral Way in Edmonds, Washington (site; Figure 1). This report has been prepared with information provided by the Port and CG Engineering, Inc. (project civil engineer) and with data collected during LAI's 2017 critical areas review and 2021 geotechnical field exploration and laboratory testing programs. 1.1 Project Description The Port proposes to develop the site with a multi -story administration and maintenance building. The building will measure 100 feet (ft) long by 70 ft wide and will have an area of approximately 6,650 square feet. Other proposed site improvements include utility upgrades and the addition of paved parking areas. The Port may install infiltration trenches and rain gardens to manage stormwater generated on site. 1.2 Scope of Services LAI provided the following geotechnical services in accordance with the scope outlined in Professional Services Agreement No. 2021-380, dated April 22, 2021: • Reviewed readily available geologic maps and geotechnical reports for the site and the surrounding area. • Coordinated the clearance of underground utilities. • Advanced one mud rotary boring into very dense subsurface soils at the proposed building location. • Collected representative soil samples to characterize site subsurface conditions. • Completed geotechnical laboratory testing and engineering analyses on select soil samples obtained from the boring. • Developed geotechnical conclusions and recommendations to support design of the proposed improvements. • Prepared this report, which includes: — a site and exploration plan (Figure 2). The plan shows the approximate locations of relevant site features and past and present borings advanced by LAI. — summary boring logs and laboratory test results. — a discussion of near -surface soil and groundwater conditions observed at the site. — seismic design considerations in accordance with the 2018 International Building Code (IBC). Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 1-1 October 4, 2021 Landau Associates — geotechnical recommendations for site earthwork and grading, including criteria for stripping depth, subgrade preparation, construction dewatering, reuse of site materials as structural fill, and structural fill placement and compaction. — geotechnical recommendations for utility construction, including criteria for trench excavation and temporary shoring, pipe foundation support, pipe bedding, initial backfill materials, and trench backfill compaction. — pavement design recommendations. — an assessment of the feasibility of infiltrating stormwater on site. — geotechnical design recommendations for shallow foundation support of the proposed structure, including allowable soil bearing capacity, lateral resistance criteria, minimum footing dimensions, slab -on -grade support, and settlement estimates. a discussion of ground improvement methods that can be used to limit settlement of the proposed building. — site and foundation drainage considerations. — recommendations for geotechnical construction monitoring. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 1-2 October 4, 2021 Landau Associates 2.0 SITE CONDITIONS The following sections describe the geologic setting of the site and the surface and subsurface conditions observed during LAI's field investigation. Interpretations of site conditions are based on LAI's review of available geologic and geotechnical information and on the results of the subsurface explorations and laboratory testing. 2.1 Geologic Setting The site is located in the Central Puget Lowland, a wide, low-lying region between the Cascade Range to the east and the Olympic Mountains to the west. The area was covered by ice sheets during the Pleistocene Epoch. Surficial deposits in the vicinity of the site primarily consist of fill (Minard 1983), likely the result of historical infilling along the Edmonds waterfront, where native marsh was partially filled to promote commercial and industrial development. Based on the results of its geologic data review, LAI infers that the fill is underlain by sediments of the Whidbey Formation, typically dense, bedded, medium- to coarse -grained sand (Minard 1983). Outcroppings of the Whidbey Formation are present along the lower bluffs of Puget Sound and may measure up to 160 ft thick in the vicinity of the site. Compressible wetland deposits may be present between the fill unit and the Whidbey Formation. 2.2 Surface Conditions The site currently is used to stockpile bark mulch and other soils; it is generally level with little to no vegetation. The site is bordered by Admiral Way to the west and BNSF Railway to the east. Surrounding development includes a marina and associated facilities, restaurants, and commercial retail spaces. 2.3 Subsurface Explorations LAI has completed two field investigations to characterize subsurface soil and groundwater conditions at the site. The first investigation was completed on June 8, 2017 and included one hollow -stem auger boring (B-1) advanced 26.5 ft below ground surface (bgs). Findings were used to prepare a critical areas report for the Port's Marine Retail Development project (LAI 2017). The second investigation was completed on May 4, 2021 and included a mud rotary boring (B-2) advanced 36.5 ft bgs. The approximate locations of the explorations are shown on Figure 2. LAI personnel monitored the explorations, collected representative soil samples, and maintained detailed logs of the subsurface soil and groundwater conditions observed. Copies of the logs and a description of the field exploration program are provided in Appendix A. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 2-1 October 4, 2021 Landau Associates Samples were transported to LAI's soils laboratory for further examination and classification. Findings are summarized in Appendix B. 2.3.1 Soil Conditions The soil conditions in boring B-1 consisted of asphalt pavement underlain by an approximately 7-ft-thick layer of medium dense to dense sand. Approximately 5 ft of very soft to soft silt with organics was observed beneath the sand. The silt was underlain by dense to very dense sand with gravel; this unit extended to the maximum depth explored (26.5 ft). The soil conditions in boring B-2 consisted of 11.5 ft of very loose to loose sand with variable silt content. An approximately 6-inch-thick silt lens was observed at 7 ft bgs, and an approximately 3-inch-thick, organic silt lens was observed at 11.25 ft bgs. The organic silt layer was underlain by medium dense to very dense sand with variable silt content; this unit extended to the maximum depth explored (36.5 ft). 2.3.2 Groundwater Conditions During LAI's June 2017 field investigation, groundwater was observed at approximately 9 ft bgs in boring B-1. Boring B-2 was advanced using the mud rotary technique, which does not allow for groundwater observation. As part of its geotechnical study, LAI reviewed groundwater monitoring data collected for the Jacobsen's Marine Facility project, located immediately north of the site (LAI 2007). Approximate depths -to -groundwater were measured on August 30, September 1, September 6, October 3, and November 11, 1995. The highest groundwater level (7.9 ft bgs, approximately 5.1 ft North American Vertical Datum of 1988 [NAVD 88]) was recorded on November 11. The groundwater conditions reported herein are for the specific locations and dates indicated and may not be representative of other locations and/or times. Groundwater conditions will vary depending on local subsurface conditions, weather conditions, tidal fluctuations, and other factors. Groundwater levels are expected to fluctuate seasonally, with maximum levels occurring during late winter and early spring. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 2-2 October 4, 2021 Landau Associates 3.0 CONCLUSIONS AND RECOMMENDATIONS Based on the results of LAI's field investigations and geotechnical engineering analyses, subsurface conditions at the site are suitable for the proposed improvements, provided the following recommendations are incorporated into the project design. 3.1 Seismic Considerations The site is located in the seismically active Pacific Northwest and could be subject to ground shaking from a moderate to major earthquake. Consequently, moderate seismic motion should be anticipated during the design life of the project, and the proposed improvements should be designed to resist seismic loading. 3.1.1 Site Classification and Seismic Design Parameters LAI understands that the proposed structure will be designed in accordance with 20181BC standards. The parameters in Table 1 can be used to compute seismic base shear forces (2017 ICC). A site -specific ground motion hazard analysis was not performed; as a result, the long -period coefficient presented in Table 1 is based on an exception in Section 11.4.8 of the American Society of Civil Engineers' (ASCE) Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16). Table 1. 2018International Building Code Seismic Design Parameters Spectral response acceleration at short period (Ss) 1.285g Spectral response acceleration at 1-second period (Si) 0.452g Site class D(a) Site coefficient (Fa) 1.0 Site coefficient (F.) 1.848(b) (a) The site includes potentially liquefiable soils and is categorized by the American Society of Civil Engineers (ASCE; 2017) as Site Class F. The ASCE provides an exception for structures with a fundamental period of vibration equal to or less than 0.5 second. LAI recommends that ground improvement activities are completed at the site to improve the engineering properties of site soil. LAI recommends the use of Site Class D if the fundamental period of vibration of the proposed structure is equal to or less than 0.5 second and ground improvement activities are completed at the site. (b) When using the coefficient Fv = 1.848, observe the Exception 2 requirements for a ground motion hazard analysis. Requirements are detailed in Section 11.4.8 of the ASCE's Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16). The coefficient should be used only to calculate T,. Fa, F = short -period (0.2-second period) and long -period (1.0-second period) site coefficients, respectively g = force of gravity S,, S1 = spectral response accelerations at 0.2- and 1.0-second periods, respectively. 3.1.2 Liquefaction and Lateral Spreading Liquefaction is a seismic hazard in which the strength and stiffness of soil is reduced by earthquake shaking, causing the soil to behave, temporarily, like a liquid. Liquefaction often occurs in loose, granular soils and non -plastic silts located below the groundwater table, during or shortly after a Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-1 October 4, 2021 Landau Associates strong seismic event. In LAI's opinion, site soils are susceptible to liquefaction and liquefaction - induced settlement. A design -level earthquake could result in differential and liquefaction -induced settlement on the order of 1.5 inches each. Seismically induced soil liquefaction can result in lateral spreading. Lateral spreading typically occurs on sloping ground or free faces underlain by loose soils and a shallow groundwater table. During a large seismic event, blocks of overburden soil may slide over lower, liquefied soil layers, displacing down slope. The site includes potentially liquefiable soils and areas of vertical relief. As such, site soils may be susceptible to lateral spreading. Using the empirical method developed by Youd et al. (2002), LAI estimates that approximately 2 to 6 inches of lateral spreading could occur at the site as a result of the design earthquake. LAI understands that the proposed administration and maintenance building will be a Risk Category II structure with no concrete or masonry wall systems. The design team has indicated that the span between bearing points (L) will be 27 ft. Per the ASCE (2017), deep foundations are required where estimated lateral spreading displacements are greater than the values identified in Table 12.13-2 (18 inches for Risk Category II structures). Structures may be supported on shallow foundations, provided the estimated liquefaction -induced differential settlement is below the limits established in Table 12.13-3 (0.010L, 3.24 inches for this structure), and the structure is designed in accordance with Section 12.13.9.2.1 (ASCE 2017). Though a structure designed in accordance with Section 12.13.9.2.1 (ASCE 2017) can be supported on shallow foundations, ground improvement, designed by a specialty contractor, is recommended to improve the static foundation performance of the structure. LAI anticipates that ground improvement will also help to reduce liquefaction and lateral spreading hazards at the site. 3.2 Earthwork and Grading Earthwork will likely consist of clearing, grubbing, and stripping areas designated for improvement and preparing building, pavement, and utility subgrades. 3.2.1 Site Preparation Existing vegetation should be cleared or grubbed in accordance with Section 2-01 of the Washington State Department of Transportation's 2021 Standard Specifications for Road, Bridge, and Municipal Construction (2021 WSDOT Standard Specifications). Material generated during clearing and grubbing should be disposed of at an approved offsite location. Sod, topsoil, and organic -rich soils should be stripped to expose underlying inorganic soil. Stripped material is not considered suitable for reuse as structural fill and should be disposed of off site or spread in areas of the site where several inches of postconstruction settlement would be tolerable. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-2 October 4, 2021 Landau Associates 3.2.2 Engineered Fill Materials Table 2 includes a list of engineered fill materials and their recommended applications. All fill materials, except Gravel Backfill for Pipe Zone Bedding and Bank Run Gravel for Trench Backfill, should be placed and compacted in accordance with Section 2-03.3(14)C, Method C of the 2021 WSDOT Standard Specifications. Gravel Backfill for Pipe Zone Bedding should be placed and compacted in accordance with Section 7-08.3(1)C of the 2021 WSDOT Standard Specifications. Pipe zone backfill and backfill above the pipe zone should be placed in accordance with Section 7-08.3(3) of the 2021 WSDOT Standard Specifications. The maximum dry density and optimum moisture content can be determined using ASTM International (ASTM) standard test method D1557, Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-Ibf/ft3 (2,700 kN- m/m3))• Table 2. Engineered Fill Materials Engineered Fill Type Granular Fill Structural Fill Top Course Base Course Gravel Backfill for Drains Gravel Backfill for Pipe Zone Bedding Specification Gravel Borrow — WSDOT Specification 9-03.14(1) Select Borrow — WSDOT Specification 9-03.14(2) Crushed Surfacing Top Course — WSDOT Specification 9-03.9(3) Crushed Surfacing Base Course — WSDOT Specification 9-03.9(3) WSDOT Specification 9-03.12(4) WSDOT Specification 9-03.12(3) Bank Run Gravel for Trench Backfill WSDOT Specification 9-03.19 Application • Imported fill material • Wet weather working platform • Replacement of overexcavated, unsuitable material • Site subgrade repair • Upper 2 inches of crushed surfacing beneath pavement • Crushed surfacing beneath pavement • Footing drain backfill • Pipe zone fill • Pipe zone bedding • Utility subgrade repair • Trench backfill above pipe zone WSDOT Specification = Washington State Department of Transportation 2021 Standard Specifications for Road, Bridge, and Municipal Construction 3.2.3 Reuse of Site Soils Soil generated from cuts and/or excavations is expected to consist primarily of sand with silt and sandy silt to silt with organics. Some soils with a high fines content are moisture sensitive; less silty material may be reused with proper moisture conditioning. Highly organic site soils should not be placed beneath footings or pavements or behind retaining walls; these soils are not recommended for reuse as utility trench backfill. Excavated material that is not suitable for reuse should be disposed of at an approved offsite location or placed in landscaped areas, where several inches of postconstruction settlement would be tolerable. If reused, site soil should meet the applicable requirements specified in Table 2. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-3 October 4, 2021 Landau Associates 3.2.4 Wet Weather Earthwork Considerations As noted, site soils generally are considered moisture sensitive. Completing earthwork during periods of wet weather or in wet conditions could result in soil disturbance and damaged subgrades. The contractor should take measures to prevent excessive soil erosion and ground destabilization from occurring during earthwork activities. If earthwork is performed during wet weather or in wet conditions, the allowable fines in structural fill should be reduced to 5 percent or less by dry weight, based on the fraction passing the %-inch sieve. Granular fill may be used to provide a stable working platform. If wet weather earthwork is unavoidable, LAI recommends: • Performing earthwork in small sections. • Sloping excavated surfaces to promote runoff. • Restricting construction traffic to areas of the site surfaced with materials that are not susceptible to wet weather disturbance. • Removing wet surficial soil daily. Soil should be removed before fill is placed. • Sealing the soil surface with a smooth drum or rubber -tired roller to reduce the extent to which soil becomes wet or unstable. • Track -walking sloped ground at the end of each workday to check that grouser marks are on -contour. • Providing upgradient perimeter ditches or low earthen berms and using temporary sumps to collect runoff and prevent ponding. 3.2.5 Subgrade Preparation Existing pavement, topsoil, organic and man-made debris, and other deleterious material should be stripped from all areas designated for improvement. LAI recommends that stripping extend approximately 6 to 12 inches bgs. Before structural fill is placed, the upper 12 inches of subgrade should be compacted to at least 95 percent of the maximum dry density, determined in accordance with ASTM standard test method D1557. The compacted subgrade should be proof -rolled with a loaded dump truck; a self-propelling, vibrating roller; or an equivalent piece of equipment. Proof -rolling should be performed in the presence of a qualified civil or geotechnical engineer, who is familiar with the site and can check for soft/and or disturbed areas. If proof -rolling reveals loose and/or disturbed subgrade, LAI recommends moisture - conditioning and recompacting the subgrade or removing and replacing loose subgrade with properly compacted structural fill. Overexcavation of unsuitable subgrade material should be completed in accordance with Section 2-03.3(14)E of the 2021 WSDOT Standard Specifications. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-4 October 4, 2021 Landau Associates 3.2.6 Temporary Construction Dewatering During LAI's June 2017 field investigation, groundwater was observed at approximately 9 ft bgs. In nearby explorations, completed in support of the Jacobsen's Marine Facility project, groundwater was observed at depths as shallow as 7.9 ft bgs (approximately 5.1 ft NAVD 88). Depending on the locations and depths of the excavations, temporary construction dewatering may be required. Dewatering should extend to a depth of at least 2 ft below the base of the excavation. Open sump pumping may be sufficient to dewater excavations that extend to the groundwater table. Wells or well points may be necessary in excavations that extend below the groundwater table. Well points are a viable option for lowering groundwater to a depth of 17 ft below the pump elevation. The contractor should be responsible for the design, installation, monitoring, and maintenance of required dewatering system(s). If wells or well points are necessary, a registered professional engineer or hydrogeologist should prepare a dewatering plan; prior to implementation, the plan should be submitted for the design team's review and comment. The plan should include provisions for limiting the effects of dewatering-induced settlement on existing structures in the vicinity of the site. 3.3 Utility Construction The following sections include geotechnical recommendations for design and construction of underground utilities. 3.3.1 Temporary Excavations Utility excavations extending through fill deposits are likely to encounter loose to medium dense sand or soft silt. While not observed in LAI's explorations, cobbles, boulders, debris, and other deleterious materials could be encountered in the fill. The contractor should be prepared to manage such unsuitable material. Trench excavation should be completed in accordance with the requirements in Section 7-08.3(1)A of the 2021 WSDOT Standard Specifications. The contractor should be responsible for actual trench configurations and the maintenance of safe working conditions, including temporary excavation stability. All applicable local, state, and federal safety codes should be followed. Temporary excavations in excess of 4 ft should be shored or sloped in accordance with Safety Standards for Construction Work, Part N (Chapter 296-155 of the Washington Administrative Code [WAC]). In the absence of groundwater seepage, Type C soils are likely to be encountered within the trench zone. The prescriptive maximum allowable excavation slope for Type C soils is 1% horizontal to 1 vertical (1%1-1:1V). If groundwater seepage is present, flatter slopes, temporary shoring, and/or dewatering may be required. Trench boxes are a worker safety device that provide lateral support of adjacent soil. Where a trench box is used to support excavations, one or both sides of the trench may cave against the box, especially if the soil is not properly dewatered. Caving may extend along the sides of the trench a Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-5 October 4, 2021 Landau Associates distance equal to the depth of the trench box. The potential for caving can be reduced by routing stormwater away from the excavation and limiting traffic and vibrations near the trench. Precautions should be taken to minimize disturbance of utility subgrades, foundation materials, and surrounding soil. Trench boxes should meet the requirements in WAC Chapter 296-155. Additional bracing or sheeting may be required where the edge of the trench is separated from settlement -sensitive structures or utilities by a distance less than 1.5 times the trench depth. If needed to support trench walls, a temporary bracing system should be designed by a structural engineer licensed in the State of Washington. The parameters in Table 3 can be used to design temporary shoring. Temporary shoring typically consists of steel plates with internal bracing. Surcharge loads, exerted by construction equipment, stockpiled material, and traffic, should be included in the temporary shoring design. Prior to construction, the design should be submitted for the design team's review and comment. Table 3. Recommended Soil Parameters for Design of Temporary Shoring Moist Unit Weight Cohesion Internal Angle of Friction (pcf) (psf) (degrees) 120 0 30 pcf = pounds per cubic foot psf = pounds per square foot 3.3.2 Pipe Foundation Support Based on the conditions observed in LAI's explorations, utility foundation soils will likely consist of very loose to medium dense sand or soft silt (fill). Provided utility subgrades are prepared as recommended in Section 3.2.5, the sand fill is anticipated to provide adequate foundation support of the proposed utilities. Very soft silt and organic silt are not anticipated to provide adequate foundation support. If these soils are encountered near the bottom of utility trench excavations, they should be overexcavated and replaced with Backfill for Pipe Zone Bedding. The backfill should be placed and compacted in accordance with the recommendations in Section 3.2.2 Exposed foundation soils could be disturbed by construction activities. If disturbed by excavation and/or foot traffic, the trench bottom should be overexcavated to expose undisturbed foundation soil. 3.3.3 Pipe Bedding and Trench Backfill Buried utility pipes should be bedded in accordance with the requirements in Section 7-08 of the 2021 WSDOT Standard Specifications. Utility trenches should be backfilled with Bank Run Gravel for Trench Backfill, as described in Section 3.2.2. Pipe zone backfill should meet the requirements in Section 7-08.3(3) of the 2021 WSDOT Standard Specifications. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-6 October 4, 2021 Landau Associates Some site soils are considered moisture sensitive and are not recommended for reuse as trench backfill. 3.4 Flexible Pavement Design Based on the results of LAI's field investigations, flexible pavements could be designed using a California bearing ratio of approximately 10 percent. LAI assumes that pavements will be constructed on subgrades prepared as recommended in Section 3.2.5. Pavement sections should be constructed on a subgrade that has been scarified to a depth of 1 ft bgs and recompacted to at least 95 percent of the maximum dry density. Adequate compaction may be difficult to achieve in fill soils that exhibit a high fines content. If construction will be completed during the wet season or in wet conditions, pavement subgrades should be overexcavated and replaced with at least 1 ft of structural fill, placed and compacted as described in Section 3.2.2. Traffic loading information was not available at the time of this writing. When developing pavement design recommendations, LAI assumed a design load of 100,000 equivalent single -axle loads; a terminal serviceability index (Pt) of 2.5; and a level of reliability of 90 percent. LAI also assumed that pavements would be subject to light vehicle traffic. A thicker pavement section will be required if heavy vehicle traffic is anticipated. Based on these assumptions, LAI recommends that pavement sections consist of 3 inches of asphalt concrete over 6 inches of crushed surfacing base course. If traffic loading information becomes available, LAI should be asked to provide updated pavement design recommendations. Asphalt concrete should be Class B aggregate material or hot -mix asphalt class % inch, PG64-22 binder, conforming to the requirements in Section 5-04 of the 2021 WSDOT Standard Specifications. The asphalt should be compacted to at least 91 percent of the Rice density. Base course material should be compacted to at least 95 percent of the maximum dry density, determined in accordance with ASTM standard test method D1557. Compacted base course should meet the requirements for Crushed Surfacing Base Course in Section 9-03.9(3) of the 2021 WSDOT Standard Specifications. To facilitate fine grading of the surface, the upper 2 inches of crushed surfacing should consist of Crushed Surfacing Top Course, as described in Section 3.2.2. Prevention of road -base saturation is essential for pavement durability; efforts should be made to limit the amount of water entering the base course. 3.5 Stormwater Infiltration Considerations The Port is considering constructing stormwater management facilities at the site. Based on the conditions observed in LAI's explorations, stormwater infiltration may be feasible at certain locations; however, the silty soils observed in borings B-1 and B-2 are considered hydraulically restricting. Furthermore, relatively shallow groundwater was observed in boring B-1 (9 ft bgs) and in nearby borings completed in support of the Jacobsen's Marine Facility project (7.9 ft bgs, approximately 5.1 ft NAVD 88). Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-7 October 4, 2021 Landau Associates An initial infiltration rate was developed for near -surface soils at the boring B-1 and B-2 locations. The infiltration rate was developed using the Soil Grain Size Analysis Method — Detailed Approach outlined in the Washington State Department of Ecology's 2012 Stormwater Management Manual for Western Washington, As Amended in December 2014 and in Appendix B of the Edmonds Stormwater Addendum (2017). Based on the results of LAI's soil grain size analysis, near -surface site soils have an estimated initial infiltration rate (Ksat;n;t;ai) of approximately 0.001 inches per hour. Correction factors should be applied to the infiltration rate to account for site variability and number of test locations, the test method used, and the degree of influent control to prevent siltation and bio buildup. In LAI's opinion, onsite stormwater infiltration is not feasible. 3.6 Foundations LAI understands that the proposed structure will be supported on continuous and isolated spread footings with column loads of 40 to 150 kips, and slabs -on -grade will be installed in maintenance and administration areas. Compressible wetland deposits are present beneath fill soils, and relatively large amounts of static settlement are anticipated. To mitigate static settlement, LAI recommends that ground improvement is completed beneath the proposed building footprint. The use of rammed aggregate piers is a viable ground improvement method for the proposed structure. Alternatively, the structure may be supported on a mat foundation. LAI's preliminary analyses indicate that, if supported by a mat foundation, the structure would experience up to 3 inches of static settlement. The following sections include recommendations for ground improvement. If the structure will be supported on a mat foundation, LAI should be contacted to provide additional recommendations. 3.6.1 Rammed Aggregate Piers If rammed aggregate piers will be used to improve foundation soils, the proposed building could be supported on conventional shallow foundations. A specialty contractor should design the piers for site -specific soil conditions and project requirements; the contractor should also prepare specifications for pier installation. Prior to pier installation, the specifications and design should be submitted for the structural and geotechnical engineers' review and approval. In LAI's opinion, an allowable bearing capacity of approximately 1,500 pounds per square foot (psf) is feasible for improved ground. Pier spacing and depth would be informed by building performance requirements. Based on LAI's discussions with a local ground improvement contractor (Geopier Northwest, Inc.), footings and slabs -on -grade may be supported by drilled GP30 piers, with compacted quarry spalls installed at the bottom of the piers. Piers would likely measure 24 inches in diameter, have an average depth of approximately 12 ft, and be spaced approximately 8 ft on center. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-8 October 4, 2021 Landau Associates Rammed aggregate piers should be installed prior to excavating the foundation subgrade. After the piers are installed, foundation excavations may be cut to finished grade. Before formwork is installed, the exposed piers should be compacted with hand -operated, vibratory equipment. 3.6.2 Shallow Foundation Support Foundation support of the proposed structure may be provided by continuous or isolated spread footings founded on properly prepared, improved ground. Bearing soil disturbed during foundation excavation should be properly recompacted or removed. All soil directly below footings should be compacted to at least 95 percent of the maximum dry density (ASTM standard test method D1557) before placement of forms, reinforcing steel, and concrete. All continuous and isolated spread footings should have minimum widths of 18 and 24 inches, respectively, and should be founded a minimum of 18 inches below the lowest adjacent final grade. Assuming the above criteria are satisfied, continuous or isolated spread footings founded directly on improved ground may be proportioned using a maximum net allowable soil bearing pressure of 1,500 psf. The term "net allowable bearing pressure" refers to the pressure that can be imposed on the soil at foundation level; it results from the total of all dead plus live loads, exclusive of the weight of the footing or any overlying backfill. The net allowable bearing pressure may be increased by one-third for transient forces, such as those induced by wind or seismic loads. Following installation of rammed aggregate piers, footing subgrades should be prepared as recommended in Section 3.2.5. Passive earth pressures that develop against the sides of building foundations, in conjunction with friction developed between the base of the footings and the supporting subgrade, will resist lateral loads transmitted from the structure to its foundation. For design purposes, the passive resistance of well -compacted fill placed against walls or the sides of foundations may be considered equivalent to a fluid with a density of 260 pcf. This value includes a safety factor of approximately 1.5 and is based on the assumption that the ground surface adjacent to the structure is level, in the direction of movement, for a distance equal to or greater than twice the embedment depth. The value is also based on the assumption that drained conditions will prevent the buildup of hydrostatic pressure in compacted fill. In design computations, the upper 12 inches of passive resistance should be neglected if the soil will not be covered by floor slabs or pavement. If future plans call for removal of the soil providing resistance, the passive resistance should not be considered. An allowable coefficient of friction of 0.33, applied to vertical dead loads only, may be used to calculate the resistance to sliding at the base of foundation elements bearing on undisturbed native soil or well -compacted granular/structural fill. If passive and frictional resistance are considered together, one-half of the recommended passive soil resistance value should be used, as larger strains are required to mobilize the passive soil resistance. The base friction design value includes a safety factor of approximately 1.5. LAI does not recommend increasing the coefficient of friction to resist seismic or wind loads. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-9 October 4, 2021 Landau Associates 3.6.3 Slab -On -Grade Support LAI understands that slabs -on -grade within the equipment maintenance and administration areas will also be supported by rammed aggregate piers. Ground improvement -supported slab -on -grade floor construction is considered feasible, provided the subgrade is properly prepared following installation of the rammed aggregate piers. Pier -supported slabs can be designed in accordance with guidance from Geopier Northwest (2016). LAI recommends using a subgrade modulus, k, of 50 pounds per cubic inch to represent the stiffness of unimproved, native site soils. Following installation of the rammed aggregate piers, slab -on -grade subgrades should be prepared as recommended in Section 3.2.5. At least 4 inches of Crushed Surfacing Base Course, as described in Section 3.2.2, should be placed beneath slab -on -grade floors to act as a capillary break layer. A condensation barrier, such as visqueen, should be placed beneath slab -on -grade floors to prevent condensation on the bottom of the floor slab and wicking through the floor slab. The condensation barrier should consist of a minimum 10-millimeter membrane with tape -sealed joints. The American Concrete Institute (ACI; 2019) guidelines recommend placing 4 inches of compacted granular material, such as Crushed Surfacing Top Course, over the barrier to facilitate curing of the concrete floor slab and to protect the vapor barrier. The ACI no longer recommends using sand as a protective layer. If moisture control within the building is critical, the condensation barrier should be inspected to verify that all openings have been properly sealed. 3.6.4 Foundation Settlement Foundations supported by properly installed rammed aggregate piers, bearing in the underlying dense to very dense Whidbey Formation, are expected to experience less than 1 inch of total settlement. Differential settlement between adjacent, ground improvement -supported foundations is expected to be less than % inch. 3.6.5 Foundation and Site Drainage LAI recommends constructing an exterior footing drainage system around the perimeter of building foundations to prevent buildup of hydrostatic pressure against subterranean walls. The drain should consist of a minimum 4-inch-diameter, perforated pipe, surrounded by at least 12 inches of filtering media. The filtering media may consist of open -graded drain rock, wrapped in a non -woven geotextile fabric (such as Mirafi° 140N, Synthetic Industries 351, or equivalent). Drainage backfill should contain less than 3 percent by weight passing the U.S. Standard No. 200 sieve, based on a wet sieve analysis of the portion passing the U.S. Standard No. 4 sieve. The drain should be sloped to carry water to a suitable collection and discharge system. To prevent the accumulation or seepage of water, the invert of the footing drainpipe should be placed at approximately the same elevation as the bottom of the footing or 12 inches below the adjacent floor slab grade, whichever is deeper. The footing drain should discharge to an approved drain system and should include cleanouts to allow for periodic maintenance and inspection. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-10 October 4, 2021 Landau Associates Positive surface gradients, adjacent to the proposed structure, should be used to direct surface water away from the foundation, toward suitable discharge facilities. Roof drainage should be discharged directly to the stormwater-collection system or another appropriate outlet. During and after construction, surface water should not be allowed to pond and soak into the ground near the buildings. 3.7 Lateral Earth Pressures on Below -Grade Walls The magnitude of lateral earth pressures that develop against subterranean walls will depend on: • the inclination of adjacent slopes; • backfill type, placement, and degree of compaction; • degree of wall restraint; • drainage provisions; • magnitude and location of adjacent surcharge loads; and • the degree to which the wall can yield laterally during or after placement of backfill. An at -rest soil pressure is exerted when a wall is restrained against lateral movement or tilting. Such wall restraint may develop if a rigid structural network is constructed prior to backfilling or if the wall is inherently stiff or otherwise restrained from rotating. In contrast, active soil pressure will be exerted if the top of a subsurface structure or wall is allowed to rotate or yield a distance equal to at least 0.001 times the height of the structure or wall. For drained, active soil conditions, non -restrained (yielding) walls with level backfill should be designed with an equivalent fluid density of 34 pcf, and restrained (non -yielding) walls with an equivalent fluid density of 54 pcf. For undrained soil conditions, yielding walls with level backfill should be designed to resist an equivalent fluid density of 80 pcf, and non -yielding walls an equivalent fluid density of 90 pcf. The equivalent fluid densities recommended for use in undrained soil conditions include hydrostatic pressure. When developing recommendations for active and at -rest earth pressures, LAI assumed that the backfill placed against below -grade walls would consist of properly compacted structural fill with no adjacent surcharge loads. If surcharge loads will occur within a horizontal distance equal to or less than the wall height, the walls should be designed to withstand the additional horizontal pressure. A uniformly distributed lateral pressure, 0.43 times the surcharge pressure, should be included for rigid walls. A uniformly distributed lateral pressure, 0.27 times the surcharge pressure, should be included for walls free to rotate during loading. A minimum surcharge pressure of 250 psf should be assumed when estimating the additional load on walls adjacent to parking areas and roadways. Dynamic lateral earth pressures should be included in the design of below -grade walls. For non -restrained (yielding) walls with a level backslope, a lateral pressure distribution of 14H (where H is the vertical height of the wall in feet) should be added to the static lateral earth pressure. The Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-11 October 4, 2021 Landau Associates recommended lateral earth pressure is based on the assumption that the wall will be free to rotate and translate a small amount during a strong motion earthquake. For restrained (non -yielding) walls with a level backslope, a lateral pressure distribution of 40H should be included in the design. LAI should be contacted for additional recommendations if the project will include walls with a non -level backslope. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 3-12 October 4, 2021 Landau Associates 4.0 REVIEW OF DOCUMENTS AND CONSTRUCTION OBSERVATIONS LAI should be asked to review geotechnical portions of the project plans and specifications to evaluate their consistency with the recommendations presented in this report. LAI also recommends that geotechnical monitoring, testing, and consultation be provided during construction to confirm that the conditions encountered are consistent with those indicated by its explorations, to provide expedient recommendations should conditions differ from those anticipated, and to evaluate whether geotechnical construction activities comply with project plans/specifications and the recommendations contained in this report. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 4-1 October 4, 2021 Landau Associates 5.0 USE OF THIS REPORT Landau Associates has prepared this report for the exclusive use of the Port of Edmonds and its design consultants for specific application to the Port Administration/Maintenance Building project in Edmonds, Washington. No other party is entitled to rely on the information, conclusions, and recommendations included in this document without the express written consent of Landau Associates. Reuse of the information, conclusions, and recommendations provided herein for extensions of the project or for any other project, without review and authorization by Landau Associates, shall be at the user's sole risk. Landau Associates warrants that, within the limitations of scope, schedule, and budget, its services have been provided in a manner consistent with that level of skill and care ordinarily exercised by members of the profession currently practicing in the same locality, under similar conditions as this project. Landau Associates makes no other warranty, either express or implied. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 5-1 October 4, 2021 Landau Associates 6.0 REFERENCES ACI. 2019. Building Code Requirements for Structural Concrete (ACI 318-19). American Concrete Institute. June. ASCE. 2017. Minimum Design Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-16). American Society of Civil Engineers, Structural Engineering Institute. ASTM. 2017. Annual Book of ASTM Standards. In: Soil and Rock (1). West Conshohocken, PA: ASTM International. Ecology. 2014. 2012 Stormwater Management Manual for Western Washington, as Amended in December 2014. Washington State Department of Ecology. Edmonds, City of. 2017. Addendum to Edmonds Community Development Code Chapter 18.30 (Edmonds Storm water Addendum). June 8. Geopier Northwest, Inc. 2016. Technical Bulletin No. 10. Structural Design Considerations for Uniformly -Loaded Floor Slabs Supported by Rammed Aggregate Pier° Elements. January. ICC. 2017. 2018International Building Code. International Code Council. September 13. LAI. 2007. Report: Geotechnical Engineering Services, Jacobsen's Marine Facility, Edmonds, Washington. Landau Associates, Inc. December 5. LAI. 2017. Wetland/Waterway Critical Areas Assessment, Port of Edmonds Marine Retail Property, Edmonds, Washington. Landau Associates, Inc. June 21. LNI. 2020. Construction Work. Chapter 296-155 WAC; Part N. Excavation, Trenching, and Shoring. Washington State Department of Labor and Industries. Effective October. Minard, J.P. 1983. Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles, Washington. Department of the Interior, US Geological Survey. WSDOT. 2020. M41-10: Standard Specifications for Road, Bridge, and Municipal Construction. 2021 Edition. Washington State Department of Transportation. September 9. Youd, T.L., C.M. Hansen, and S.F. Bartlett. 2002. Revised Multilinear Regression Equations for Prediction of Lateral Spread Displacement. Journal of Geotechnical and Geoenvironmental Engineering. 128(12). Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building 6-1 October 4, 2021 Puget Sound Project Location N 0 0.5 1 Miles Data Source: Esri 2012 Port Administration and LANDAU Maintenance Building ASSOCIATES Edmonds, Washington v (city Park O Vicinity Map I!!l 'm 1� • Seattle Spokane Tacoma Hympia Washington Figure 1 Lanaau Hssoaaces I❑:\vrojeccs\ii3\u.5y\uiu\uii\ruz �,¢e rlan.awg I Jgz4lzuzi Gll YIVI I eziCK CIM R�12.32 RIM=11.34 6" DI NW IE=9.32 6-PVC ENE IE:�4.94 GAS I II \ P TUA�ISTRANS 1---`12— so ss ss ss ss ss SS L x _ _ i w- W* - - WW5Mt G \ I 20' ROV�NG GATE 5' HAINLINK FENCE W/ BARBWIRE I `� + //410" Z// Legend B-1 & Boring location and designation �,�`#-•fit=: 0 40 80 Scale in Feet — � _ I o RIM=11.E cr c* c� c- 6" PVC s ss ss s_ _ ss ss ss ss 1 -::L N.C_ W* W* w* 2, 8' SWINGING GAT S OUTDOOR \ \ DISPLAY SITE 20,880 SF 0.48 ACRES iI ifi� C "CC E 6' CHAINLINK ABOVE GROUND POWERLIN Burlington Northern Santa Fe Railroad Base Map Source: Jackson Main Architecture 2017 Port Administration and Figure Maintenance Building Site and Exploration Plan Edmonds, Washington APPENDIX A Field Explorations APPENDIX A FIELD EXPLORATIONS Landau Associates, Inc. (LAI) and its drilling subcontractor, Holocene Drilling, Inc., have completed two field investigations to characterize subsurface soil and groundwater conditions at the site. The first investigation was completed on June 8, 2017 and included one hollow -stem auger boring advanced 26.5 feet (ft) below ground surface (bgs). The second investigation was completed on May 4, 2021 and included one mud rotary boring advanced 36.5 ft bgs. The boring locations were identified using existing infrastructure as a field reference (Figure 2). The ground surface elevation was not determined at either exploration location. LAI personnel monitored the explorations, obtained representative soil samples, maintained a detailed record of the subsurface soil and groundwater conditions observed, and described the soil by visual and textural examination. Each representative soil type was described using the soil classification system shown on Figure A-1, in general accordance with ASTM International standard test method D2488, Standard Practice for Description of Soils (Visual -Manual Procedures). The summary boring logs on Figures A-2 and A-3 represent LAI's interpretation of site subsurface conditions. The stratigraphic contacts shown on the logs represent the approximate boundaries between soil types; actual transitions may be more gradual. The soil and groundwater conditions depicted are for the specific locations and dates reported and may not be representative of other locations and/or times. Disturbed soil samples were obtained at select intervals using a 1.5-inch-inside-diameter split -spoon sampler. A 140-pound automatic hammer, falling approximately 30 inches, was used to drive the sampler 18 inches (or a portion thereof) into the undisturbed soil. The number of blows required to drive the sampler for the final 12 inches of soil penetration (or a portion thereof) is noted on the boring logs, adjacent to the appropriate sample notation. Samples were transported to LAI's soils laboratory for further examination and testing. Test results and a discussion of testing procedures are presented in Appendix B. Upon completion of drilling and sampling, the boreholes were decommissioned in general accordance with the requirements in Washington Administrative Code 173-160. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building A-1 October 4, 2021 MAJOR DIVISIONS Soil Classification System uscs GRAPHIC LETTER SYMBOL SYMBOL') TYPICAL DESCRIPTIONS 121(3) GRAVEL AND CLEAN GRAVEL "' p; :o: ;a: GW Well -graded ravel; ravel/sand mixture(s); little or no fines 9 9 9 J N N O m'� GRAVELLY SOIL (Little or no fines) Poorly graded ravel; ravel/sand mixtures little or no fines Y9 9 9 mixture(s); o. o o. GP GRAVEL WITH FINES GM ❑ 6 >0 (More than 50% of Silty gravel; gravel/sand/silt mixture(s) w E 'v, coarse fraction retained (Appreciable amount of Qo 0 N on No. 4 sieve) fines) GC Clayey gravel; gravel/sand/clay mixture(s) e (� � z SAND AND CLEAN SAND $W Well -graded sand; gravelly sand; little or no fines w m C u) L m SANDY SOIL (Little or no fines) Poorly graded sand; gravelly sand; little or no fines $P �t SAND WITH FINES $M < o 6 00 (More than 50% of fraction Silty sand; sand/silt mixture(s) g @ coarse passed (Appreciable amount of SC — through No. 4 sieve) fines) Clayey sand; sand/clay mixture(s) ML Inorganic silt and veryfine sand; rock flour; silty or clayey fine sand or clayey silt with slight po t �, N `,' SILT AND CLAY plasticity Inorganic clay of low to medium plasticity; gravelly clay; sandy C L uy L0@ (Liquid limit less than 50) clay; silty clay; lean clay > Z E y OL Organic silt; organic, silty clay of low plasticity - n o MH Inorganic silt; micaceous or diatomaceous fine sand E m N SILT AND CLAY uj @ CH Inorganic clay of high plasticity; fat clay z° Z E L� (Liquid limit greater than 50) Organic clay of medium to high plasticity; organic silt OH HIGHLY ORGANIC SOIL PT Peat; humus; swamp soil with high organic content GRAPHIC LETTER OTHER MATERIALS SYMBOL SYMBOL TYPICAL DESCRIPTIONS PAVEMENT '.:. AC Or PC Asphalt concrete pavement or Portland cement pavement ROCK RK Rock (See Rock Classification) WOOD WD Wood, lumber, wood chips DEBRIS O O O DB Construction debris, garbage Notes: 1. USCS letter symbols correspond to symbols used by the Unified Soil Classification System and ASTM classification methods. Dual letter symbols (e.g., SP-SM for sand or gravel) indicate soil with an estimated 5-15% fines. Multiple letter symbols (e.g., ML/CL) indicate borderline or multiple soil classifications. 2. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils (Visual -Manual Procedure), outlined in ASTM D 2488. Where laboratory index testing has been conducted, soil classifications are based on the Standard Test Method for Classification of Soils for Engineering Purposes, as outlined in ASTM D 2487. 3. Soil description terminology is based on visual estimates (in the absence of laboratory test data) of the percentages of each soil type and is defined as follows: Primary Constituent: > 50% - "GRAVEL," "SAND," "SILT," "CLAY," etc. Secondary Constituents: > 30% and < 50% -'very gravelly," "very sandy," "very silty," etc. > 15% and < 30% - "gravelly," "sandy," "silty," etc. Additional Constituents: > 5% and < 15% - "with gravel," "with sand," "with silt," etc. < 5% - "with trace gravel," "with trace sand," "with trace silt," etc., or not noted. 4. Soil density or consistency descriptions are based on judgement using a combination of sampler penetration blow counts, drilling or excavating conditions, field tests, and laboratory tests, as appropriate. Drilling and Sampling Key Field and Lab Test Data SAMPLER TYPE SAMPLE NUMBER & INTERVAL Code Description Code Description a 3.25-inch O.D., 2.42-inch I.D. Split Spoon PP = 1.0 Pocket Penetrometer, tsf b 2.00-inch O.D., 1.50-inch I.D. Split Spoon Sample Identification Number TV = 0.5 Torvane, tsf c Shelby Tube F___ PID = 100 Photoionization Detector VOC screening, ppm d Grab Sample Recovery Depth Interval W = 10 Moisture Content, % e Single -Tube Core Barrel 1 1 ~ Sample Depth Interval D = 120 Dry Density, pcf f Double -Tube Core Barrel J -200 = 60 Material smaller than No. 200 sieve, % g 2.50-inch O.D., 2.00-inch I.D. WSDOT Portion of Sample Retained GS Grain Size - See separate figure for data h 3.00-inch O.D., 2.375-inch I.D. Mod. California for Archive or Analysis AL Atterberg Limits - See separate figure for data i Other - See text if applicable GT Other Geotechnical Testing 1 300-lb Hammer, 30-inch Drop CA Chemical Analysis 2 140-lb Hammer, 30-inch Drop Groundwater 3 Pushed 4 Vibrocore (Rotosonic/Geoprobe) Approximate water level at time of drilling (ATD) 5 Other - See text if applicable 1 Approximate water level at time after drilling/excavation/well Port Administration and Figure LANDAU Maintenance Building Soil Classification System and Key /� �I ASSOCIATES Edmonds, Washington A_ I 0 M n B-1 SAMPLE DATA SOIL PROFILE o Drilling Method: Hollow -Stem Auger � a> *6T a o E Ground Elevation (ft): Not Determined z O 2> o 4: co0) m > U V! L a a) o w in — 0-n m a E U) U) Logged By: SMG Date: 06/08/17 0 rn AC Asphalt pavement (3-inch thickness) SID (ASPHALT) SM Gray, gravelly SAND with silt (medium dense, moist to wet) (FI LL) L W=9 1 b2 28 -200 = 6 4 W=15 ' 2 b2 18 GS 6 ML Gray -brown SILT with organics 8 3 b2 2 Sand lens at 11.4 ft (very soft to soft, moist to wet) (ALLUVIUM) 10 4 b2 3 W = 55 AL 12 SP Gray, fine to coarse SAND with gravel, W = 16 trace silt (dense to very dense, wet) 5 b2 34 -200 = 5 (WHIDBEY FORMATION) 14 6 b2 54 16 18 20 Notes: 1. Stratigraphic contacts are based on field interpretations and are approbmate. 2. Reference to the text of this report is necessary fora proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key' figure for explanation of graphics and symbols. Port Administration and LAI Project No: 0173039.010 Moisture Content (%) Plastic Liquid Limit I�� Limd 20 40 60 80 - SPT N-Value - A Klb Standard N-Value A 3 20 40 60 80 z X Fines Content (%) X 0 20 40 60 80 LALANDAU Maintenance Building Log of Boring B-1 ASSOCIATES Edmonds, Washington A • 0 M 0 M n SAMPLE DATA E a) 0- z� ~ ° _ L 0 N 0 O N w cn xs N rn m 0 7 b2 831 g.. 8 E I I b2 1 56 Boring Completed 06/08/17 Total Depth of Boring = 26.5 ft. B-1 SOIL PROFILE a Drilling Method: Hollow -Stem Auger 0 E Ground Elevation (ft): Not Determined t>>1 U U! fl rn U) Logged By: SMG Date: 06/08/17 SP Gray, fine to coarse SAND with gravel, trace silt (dense to very dense, wet) (WHIDBEY FORMATION) LAI Project No: 0173039.010 Moisture Content (%) Plastic Liquid Limit I�� Limd 20 40 60 80 - SPT N-Value - A Klb Standard N-Value A 3 20 40 60 80 z X Fines Content (%) X 0 20 40 60 80 83/ 40 Notes: 1. Stratigraphic contacts are based on field interpretations and are approbmate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key' figure for explanation of graphics and symbols. Port Administration and LALANDAU Maintenance Building Log of Boring B-1 ASSOCIATES Edmonds, Washington Figure A-2 (2 of 2) 0 M 0 M n B-2 SAMPLE DATA SOIL PROFILE o Drilling Method: Mud Rotary a> o a T o E Ground Elevation (ft): Not Determined z O N> o LL m m 0) U > V! 3 -O o a) w in — Q Un m C) a)U) fl. fn Logged By: BCS Date: 05/04/21 j 2 rn 0 SP Tan, fine to medium SAND with trace gravel (loose, moist) (FILL) 2 Z a) N 0 S-1 b2 8 ° z 4 0 3 c 2 SW- Gray, gravelly SAND with silt (loose, moist) S-2 b2 8 = W 19 SM 6 GS ML Gray, sandy SILT with trace gravel (soft, S-3B b2 8 W =24 — SP' moist) ------------------ 8 SM Grayish -black SAND with gravel, silt (very S-3A W = 23 '. loose to loose, wet) GS 10 S-4 b2 2 W = 63 '. S-413 W = 101 OL Grayish -brown ORGANIC SILT (very soft, SP_ moist to wet) 12 SM (ALLUVIUM) Blackish -gray, gravelly SAND with silt (medium dense, wet) (WHIDBEY FORMATION) �-14 S-5 b2 24 W = 14 16 GS GS-1 J] d W = 5 18 Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key' figure for explanation of graphics and symbols. Port Administration and LALANDAU Maintenance Building Log of Boring B-2 ASSOCIATES Edmonds, Washington LAI Project No: 0173039.010 Moisture Content (%) Plastic Liquid Limit Limit 20 40 60 80 - SPT N-Value - A Klb Standard N-Value A 20 40 60 80 X Fines Content (%) X 20 40 60 80 • A 1011 Figure A-3 (1 of 2) 0 M 0 M n B-2 LAI Project No: 0173039.010 SAMPLE DATA SOIL PROFILE Moisture Content (%) Plastic Liquid Limit Limit 20 40 60 80 a> o a o Drilling Method: Mud Rotary A - SPT N-Value T o E E Ground Elevation (ft): Not Determined ? o Klb -Standard N-Value A o @ ) t> @ 3 20 40 60 80 L m o iv _ 0- i° N L a U) a C z X Fines Content (%) X a) 2 m m ° a m U) Loed By: BCS Date: 05/04/21 Logged 0 o w u) os rn m C9 0 20 40 60 80 20 SP- Blackish -gray, gravelly SAND with silt SM (medium dense, wet) - S-61 b2 33 (WHIDBEY FORMATION) - A -with gravel - -dense 22 (D Z a) N 0 O Z iu 24 m c 2 SP Uight gray, very gravelly, fine tc coarse SAND with trace silt (very dense, wet) S-7 b2 60 - 26 ........... :................ :....... 28 - 30 SP- Uight gray, very gravelly SAND with silt SM (dense, wet) - S-8 b2 50 - 32 - 34 - S-9 b2 48 - a 36 Boring Completed 05/04/21 Total Depth of Boring = 36.5 ft. 40 Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate. 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions. 3. Refer to "Soil Classification System and Key' figure for explanation of graphics and symbols. Port Administration and Figure LALANDAU Maintenance Building Log of Boring B-2 A-3 ASSOCIATES Edmonds, Washington (2 of 2) APPENDIX B Laboratory Soil Testing APPENDIX B LABORATORY SOIL TESTING Samples obtained from the borings were transported to Landau Associates, Inc.'s soils laboratory for further examination and testing. Laboratory tests were performed in accordance with the ASTM International (ASTM) standard test methods noted below. Natural Moisture Content Natural moisture content determinations were completed in general accordance with ASTM standard test method D2216. The results of the moisture content determinations are shown as "W = xx" in the "Test Data" column on Figures A-2 and A-3. Grain Size Analysis Grain size analyses were completed in general accordance with ASTM standard test method D422. Samples selected for grain size analysis are designated with a "GS" in the "Test Data" column on Figures A-2 and A-3. The test results are presented on Figure B-1. U.S. Standard No. 200 Wash Sieve To provide an indication of the fines content of site soils, select samples were washed over a U.S. Standard No. 200 sieve in general accordance with ASTM standard test method C117. Samples selected for U.S. Standard No. 200 washes are designated with a "-200 = xx" in the "Test Data" column on Figures A-2 and A-3. Atterberg Limit Test An Atterberg limits test was completed in general accordance with ASTM standard test method D4318. The purpose of the test was to determine the liquid limit, plastic limit, and plasticity i ndex of fine-grained site soils. The sample selected for the Atterberg limits test is designated with an "AL" in the "Test Data" column on Figure A-2. The test results are presented on Figure B-2. Geotechnical Engineering Report 0173039.010.011 Port Administration and Maintenance Building B-1 October 4, 2021 173039.01 10/3/21 C:\USERS\MSKINNER\DESKTOP\0173039.010.GPJ GRAIN SIZE FIGURE STRAIGHT LINE U.S. Sieve Opening in Inches U.S. Sieve Numbers Hydrometer 6 4 3 2 1.5 1 1/2 3/8 3 4 6 810 1416 20 30 40 5060 100 140 200 100 90 80 70 L 60 50 Q) 40 o_ 30 20 10 0 100 10 1 0.1 0.01 0.001 Grain Size in Millimeters Cobbles Gravel Sand Silt or Clay Coarse Fine Coarse Medium Fine Symbol Exploration Sample Depth Natural Port Administration and Figure LANDAU ASSOCIATES Maintenance Building Edmonds, Washington Grain Size Distribution -�I B I Number Number (ft) o Moisture (/o) Soil Description Unified Soil Classification • B-1 S-2 5.0 15 Gravelly SAND with silt SP-SM m B-2 S-2 5.0 19 Gravelly, fine to coarse SAND with silt SW-SM A B-2 S-3A 8.0 23 Fine to coarse SAND with gravel and silt Gravelly, fine to coarse SAND with silt SP-SM * B-2 S-5 15.0 14 SP-SM 0 60 50 40 a 20 10 0 CL CH CL-ML M or OL MH or OH 0 10 20 30 40 50 60 70 80 90 100 110 Liquid Limit (LL) ATTERBERG LIMIT TEST RESULTS Natural Exploration Sample Liquid Plastic Plasticity Symbol Number Number Depth Limit Limit Index Moisture Soil Description (ft) (%) (%) (%) (%) • B-1 S-4 10.0 43 27 16 55 SILT with organics ASTM D 4318 Test Method LANDAU LA ASSOCIATES Port Administration and Maintenance Building Edmonds, Washington Plasticity Chart t Soil ation Figure B-2 Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section VI, Page 1 Section VI — Other Permits Section VI Summary: Narrative Other permits are not anticipated to be required for this project besides those from the City of Edmonds. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 Drainage Report April 01, 2022 Section VII, Page 1 Section VII — Bond Quantities. Declaration of Covena Operation and Maintenance Manual Section VII Summary: Narrative The Bond Quantity Worksheet is a standalone document that can also be submitted to the City of Edmonds separately from this document. A Declaration of Covenant is not required since no LID BMPs are proposed for the project. The Operation and Maintenance Manual is a standalone document that will be given to the owner following the construction of the project. 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section VII, Page 2 Port of Edmonds Admin Building 471 Admiral Way Edmonds, WA 98020 OPERATION AND MAINTENANCE MANUAL Date: April 2022 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Port of Edmonds Admin Building - CG #21160.20 April 01, 2022 Drainage Report Section VII, Page 3 Operation and Maintenance Manual This Operation and Maintenance Manual has been drafted for Port of Edmonds Admin Building, a 7,294 sf building project on a 0.48 acre site. The proposed storm system primarily consists of catch basins and conveyance pipes. Runoff from the site roof area is routed through roof drains, and runoff from other impervious areas will flow through catch basins and conveyance pipes. Runoff will outlet to an existing storm main on Admiral Way. Included in this Operation and Maintenance Manual is an 11" x 17" Grading and Drainage Plan sheet showing the location of the system. Please note that this map is generated during the design phase and may not reflect all changes made in permitting and construction. CG Engineering may be contacted for an updated copy of this map once the as -built drawings are completed for the site. The contractor will be responsible for the maintenance and operation of all stormwater structures and BMPs requiring maintenance during construction, and after construction, responsibility will pass to the owner. A map of the project area can be seen on the following page in Figure VII-1. Included in this manual are maintenance sheets taken from the 2012 Stormwater Management Manual for Western Washington (as amended in 2014) for the following facilities/activities: Catch Basins: Concrete structures with steel grates that collect stormwater runoff from the site and act as junctions for storm conveyance pipes. Vegetation Management: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Facilities shall be inspected for defects listed in the following facility sheets. Most maintenance tasks are generally reactionary to a defect being found, rather than a matter of constant upkeep. It is generally expected that few to none of these defects will be present upon the yearly inspection of each facility. The facility sheets list the potential conditions warranting maintenance and the expected result following any maintenance. Several engineer's notes for specific tasks are provided within the facility sheets. Unless otherwise noted on the facility sheets the maintenance tasks should be performed on an "as needed" basis: (a) when the described defect is visible to whomever performs the yearly inspection, or (b) should any defect become apparent between inspections. 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com ASPHALT SS SS SS ANTHONY GUEST '>:1" PARKING SIGN / W" W" 2.30 F 12.42 _ - _- TOC: 12.92 12.99 12.49 °1242 G* 3S SS SS G� I V /72 W"ten �� I IZ I I II I I I 3 I I I a I 1 .25 I 3 I T- 12_75 ------ 12.16_ I 13 k I � I I I "T G" POTHOLE AND VERIFY ALL eCROSSI LET NG UTILIFROMTIES ON STORM OUTSITE PRIOR TO I 5 SS SS SS SS -5s SS UTILITY CONSTR"TION ADMIRAL WAY -�--+- W* W* W" W N _ W* I TYPE ICB - (2) RISERS W/ 7" RISE, 11" TREAD / (INSTALL BACKWATER VALVE ON NW It DOWNSTREAM OF CB) RIM: 11.44 . IE (12' PVC SE)9.0 W22.04IE(12"DIP 088� GRADING AND DRAINAGE PLAN NOTES: (- -7 I 1. SOILS REPORT I I 1_ SD REPORT NUMBER: 0173039.010.011 I I I PREPARED BY: LANDAU ASSOCIATES I I I DATED: 10/04/2021 I I G* 2. A MINIMUM OF T HORIZONTAL SEPARATION AND V VERTICAL SEPARATION IS REQUIRED BETWEEN DRY ! UTILITIES (POWER, GAS, PHONE, CABLE, ETC) AND SEWER, WATER AND STORM, AND A MINIMUM OF 5' HORIZONTAL SEPARATION AND V VERTICAL SEPARATION FROM ANY CITY OWNED LINES. �j -SS SS I 1 3. NEW/REPLACED IMPERVIOUS SURFACE (INCLUDING ROW): 23,598 SF - NEW BUILDING: 7,294 SF ROOF AREA. RUNOFF ROUTED TO PUBLIC STORM MAIN THROUGH ROOF I - I DRAINS. - NEW SIDEWALK: 1,222 SF. RUNOFF COLLECTED BY CATCH BASINS. I MAINTAIN EXISTING - NEW DRIVEWAY:12,251 SF. RUNOFF COLLECTED BYCATCH BASINS. I I- o -�I SLOPE !TOWARDS - LANDSCAPING: 1,820 SF. RUNOFF COLLECTED BY CATCH BASINS. a !TOWARDS EXISTING CB - ROW SIDEWALK: 1,934 SF. RUNOFF COLLECTED BY ROW CATCH BASIN. ROW DRIVEWAY: 898 SF. RUNOFF COLLECTED BY ROW CATCH BASIN. I - I I I I I I I 4. ALL DISTURBED AREAS TO BE COMPOST AMENDED PER 2014 SWMMWW BMPTS.13. I I I j 11.51 TYPE I CB 3 RIM: II.OE �: w • ri ro I\ •I \ ENTRY: 14.00 )'{ U I Y '.{, c ENTRY: 14.21 DRY UTILITI DESIGNED II :ONNECT AS DESIGNED BY OC: 13.114 4 � � `'IIIIIIII r e CTRICAL CONSULTANT OR ENTRY: 14.21 SERVICE PROVIDERS 12.64 3a. - ENTRY: 14.00 p I °. TOC: 13.88 < 14.15 - Ij.. 13.38 ROOFANDFOOTINGDRAIN N 14.13 I \ °o'13.8 13. 8 e ;J PROPOSED BUILDING 1338 a 13.24 3 13.sa i FFE:14.0 1a.ao \ TOC: 12.90 12.40 a LANDING AREA, TYP m ° -_ 13.04 i '..' (1.5%MAX SLOPE) \\* e _i ^a 13.32 3 1�jJl4 13.31 13.46 113.97 3.36 13.24 13AS 3 A g �I 13.16 TYP 13.55 14.0 GARAGE ENTRY: 14.0 GARAGE ENTRY: 14.0 TOC: 13.85 13.78 2 12.72 TYPE II CB W/ SOLID LID RIM: 11.571E (6" PVC 5W ): 9.14 IE (6" PVC S): 9.14 IE6DIVS%14 8" PW1E (CE)94 1 3 IE (12" PVC NW): 9.14 12.31 Gl MODULAR WETLAND SYSTEM (MWS) W/ CURB INLET 1 RIM: LIZ C3.3 IE IN (8" PVC SE): 9.45 IE OUT (8" PVC NW): 9.19 Irsrm PAVING LEGEND - NEW ASPHALT OVERLAY EXISTING ASPHALT/UTILITYSAWCUT NEW CONCRETE GRADING QUANTITIES TOTAL EXCAVATION (CUT) - 30 CU YDS TOTAL EMBANKMENT (FILL) 530 CU YDS TOTAL 560 CU YDS THE QUANTITIES SHOWN ABOVE ARE FOR THE PERMIT PROCESS ONLY. THESE VALUES ARE APPROXIMATE. DO NOT USE FOR BIDDING, PAYMENT, OR ESTIMATING PURPOSES. a/a a/a- a/a j/n a/a- V. a/a- i/a a/a- a/a- a/ TAi/a 13.68 13.08 ENTRY: 11.11 I 4" DIA PERFORATED PVC PIPE GRAVEL NUS WITH ALLAROUND,IWRAPPED IN 8" IN FROM WOOD. NON -WOVEN GEOTEXTILE SEE STRUCTURAL DRAWINGS MAINTAIN EXISTING FLOW a FABRIC, SLOPE AT 0.5%MIN. CHANNEL I - \ _ TYPE I CB W/ DOWNTURN ELBOW I TURN DOWN PERFORATIONS SHOWN Y RIM: 12.48 2 3 4 IE (8" DIP NE): 10.67 I 3 C3. C3. C3. 6" DOWNSPOUT SYSTEM r I FINISHED GRADE I TO CONVEYANCE SYSTEM@ 0.5%MIN. PLACE NEXT TO wA wA-WSWa wnwA--WA-wA-wA--W�-w I FOOTING DRAIN OR AS - W Ai--wn wn-wn wr,w wn-wn-wn \ `.0% TRASH AREA SEE ARCH PLANS - d J i 12.74 SHOWN ON GRADING & -III 13.25 12.75 DRAINAGE PLAN 149 LF ^ 8" DIP @ 0.5% `.8%I I.s (CONTRACTOR MAY LOCATE cob 13.19 zT 1.5 TYPE ICB ON EITHER SIDE OF O RIM: 12.45 0. p 13.57 I IE (81,DIP SW): 9.92 FOOTING DRAIN) 00 00 13.04 _ _ _ 13.22 IV, PVC NW): 9.92 p c I 3 4 sis,.C� 13.01 • - I C3. C3. C3. LINE OF MAX EXCAVATION. Q •a o 06 e d n 'd SIL IS RECYCLE AREA `Q i d3.ad 13.36 13,51 F REPLACE WITH CA WITH O�0 e0 13.82 13.00 CONCRETE / - _ 1' 6' CHAIf �� FOOTING j yy 1 GRADING AND DRAINAGE PLAN © 2 FOOTING AND ROOF DRAIN SECTION 1 SCALE: 1" = 10' 10 0 5 10 20 UTILITY CROSSING 15 It (GAS LINE): UNKNOWN, FINISHED - 15 FIELD VERIFY BADE TYPE I CB IE (12" DIP STORM): 8.88 G (INSTALL BACKWATER VALVE ON NW IE DOWNSTREAM OF CB) RIM: 11.44 30 '38LF-12"DIP 0.5%' ' I' 10 IE(12"PVC SE): 9.08 EXIST CB#1544 IE (12"DIPNW):9.08 RIM: 11.51 2 3 4 IE (12" CONC NNE): 9.21 IF (12" CONC SW): 8.86 UTILITY CROSSING UTILITY CROSSING It (8" CL WATER): 7.50 5 IE(8" CONC SEWER): 7.74 ' ' ' ' ' ' (FIELD VERIFY) 5 IE (12" DIP STORM): 8.95 IE (12" DIP STORM): 9.01 a ADMIRAL WAY STORM PROFILE v SCALE: HORIZ: 1"=1O%VERT: 1"=5' BLD2021-1384 APPROVED FOR CONSTRUCTION CITY OF EDMONDS DATE: BY: CITY ENGINEERING DIVISION 11 JACKSON I MAIN ARCHITECTURE 311 FIRST AVENUE SOUTH SEATTLE, WA 98104 t 206 324 4800 W W W JACKSONMAIN.COM 04101122 V) 0 O CD Uj Q 0 Lu 3: ILL. o < o o U) Q m 0 co � zQ0 w 0coww U) 0� O R C LuQ� LU p-Q LL 00 Qa�: �_U) 0 Z 00 0 2 0- Q D-vw m oak=mm a E3 o > > w�5mm w w m IY o O O o o `Bog C � 6VG1 RNEE 1M 250 4TH RYE. S., SURE 200 EDMONDS. WASHINOTON 58020 PHONE (425) 778-85N PAX (a25) T78�5588 CG#: 21160.20 PROJECT NO.: 21160 PROJECT MGR.: JPU DRAWN BY: ATD CHECKED BY: GAG GRADING AND DRAINAGE PLAN AND DETAILS C3.1 MON I MAIN ARC-ECTURE P.S.- Port of Edmonds Admin Building - CG 421160.20 April 01, 2022 Drainage Report Section VII, Page 4 i; . 440 � 1 ` Q - Ia o F: rd r Figure VII-1. Map of project area (from Edmonds GIS). 4M 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com Biov� Clean A Forterra Company Northwes OPERATION & MAINTENANCE MANUAL w� 0 J Inspection Guidelines for Modular Wetland System - Linear Inspection Summary WETLANDS o Inspect Pre -Treatment, Biofiltration and Discharge Chambers - average inspection interval is 6 to 12 months. ■ (15 minute average inspection time) . o NOTE: Pollutant loading varies greatly from site to site and no two sites are the same. Therefore, the first year requires inspection monthly during the wet season and every other month during the dry season in order to observe and record the amount of pollutant loading the system is receiving. System Diagram Access to separation chamber and pre -filter cartridges Individual Media filters Cart Curb Prefilter Cartridge 0 __J7 Vertical Underdrain Manifold UluMtz' lu EEN 0 Pre-treatment Chamber 0 Biofiltration Chamber O3 Discharge Chamber l Access to discharge hamber and orifice control Drain -Down Line Flow Control Riser O 3 Outlet Pipe www.modularwetlands.com Inspection Overview WETLANDS As with all stormwater BMPs inspection and maintenance on the MWS Linear is necessary. Stormwater regulations require that all BMPs be inspected and maintained to ensure they are operating as designed to allow for effective pollutant removal and provide protection to receiving water bodies. It is recommended that inspections be performed multiple times during the first year to assess the site specific loading conditions. This is recommended because pollutant loading and pollutant characteristics can vary greatly from site to site. Variables such as nearby soil erosion or construction sites, winter sanding on roads, amount of daily traffic and land use can increase pollutant loading on the system. The first year of inspections can be used to set inspection and maintenance intervals for subsequent years to ensure appropriate maintenance is provided. Without appropriate maintenance a BMP will exceed its storage capacity which can negatively affect its continued performance in removing and retaining captured pollutants. Inspection Equipment Following is a list of equipment to allow for simple and effective inspection of the MWS Linear: • Modular Wetland Inspection Form • Flashlight • Manhole hook or appropriate tools to remove access hatches and covers • Appropriate traffic control signage and procedures • Measuring pole and/or tape measure. • Protective clothing and eye protection. • 7/16" open or closed ended wrench. • Large permanent black marker (initial inspections only - first year) • Note: entering a confined space requires appropriate safety and certification. It is generally not required for routine inspections of the system. www.modularwetlands.com WETLANDS Insaection Steas The core to any successful stormwater BMP maintenance program is routine inspections. The inspection steps required on the MWS Linear are quick and easy. As mentioned above the first year should be seen as the maintenance interval establishment phase. During the first year more frequent inspections should occur in order to gather loading data and maintenance requirements for that specific site. This information can be used to establish a base for long term inspection and maintenance interval requirements. The MWS Linear can be inspected though visual observation without entry into the system. All necessary pre -inspection steps must be carried out before inspection occurs, especially traffic control and other safety measures to protect the inspector and near -by pedestrians from any dangers associated with an open access hatch or manhole. Once these access covers have been safely opened the inspection process can proceed: • Prepare the inspection form by writing in the necessary information including project name, location, date & time, unit number and other info (see inspection form). • Observe the inside of the system through the access hatches. If minimal light is available and vision into the unit is impaired utilize a flashlight to see inside the system and all of its chambers. • Look for any out of the ordinary obstructions in the inflow pipe, pre-treatment chamber, biofiltration chamber, discharge chamber or outflow pipe. Write down any observations on the inspection form. • Through observation and/or digital photographs estimate the amount of trash, debris and sediment accumulated in the pre-treatment chamber. Utilizing a tape measure or measuring stick estimate the amount of trash, debris and sediment in this chamber. Record this depth on the inspection form. www.modularwetlands.com 1--,, WETLANDS • Through visual observation inspect the condition of the pre -filter cartridges. Look for excessive build-up of sediments on the cartridges, any build-up on the top of the cartridges, or clogging of the holes. Record this information on the inspection form. The pre -filter cartridges can further be inspected by removing the cartridge tops and assessing the color of the BioMediaGREEN filter cubes (requires entry into pre-treatment chamber — see notes above regarding confined space entry). Record the color of the material. New material is a light green in color. As the media becomes clogged it will turn darker in color, eventually becoming dark brown or black. Using the below color indicator record the percentage of media exhausted. New Exhausted RinMPdIaGRFFN I BioMediaGREEN 0% -- Percent Clogged -- 100% • The biofiltration chamber is generally maintenance free due to the system's advanced pre- treatment chamber. For units which have open planters with vegetation it is recommended that the vegetation be inspected. Look for any plants that are dead or showing signs of disease or other negative stressors. Record the general health of the plants on the inspection and indicate through visual observation or digital photographs if trimming of the vegetation is needed. • The discharge chamber houses the orifice control structure and is connected to the outflow pipe. It is important to check to ensure the orifice is in proper operating conditions and free of any obstructions. Generally, the discharge chamber will be clean and free of debris. Inspect the water marks on the side walls. If possible, inspect the discharge chamber during a rain event to assess the amount of flow leaving the system while it is at 100% capacity (pre- treatment chamber water level at peak HGL). The water level of the flowing water should be compared to the watermark level on the side walls which is an indicator of the highest discharge rate the system achieved when initially installed. Record on the form is there is any difference in level from watermark in inches. www.modularwetlands.com 1--,' WETLANDS • NOTE: During the first few storms the water level in the outflow chamber should be observed and a 6" long horizontal watermark line drawn (using a large permanent marker) at the water level in the discharge chamber while the system is operating at 100% capacity. The diagram below illustrates where a line should be drawn. This line is a reference point for future inspections of the system: Water Level Marks i Water Level Mark Using a permanent marker draw a 6 inch long horizontal line, as shown, at the i higher water level in the MWS Linear discharge chamber. • Water level in the discharge chamber is a function of flow rate and pipe size. Observation of water level during the first few months of operation can be used as a benchmark level for future inspections. The initial mark and all future observations shall be made when system is at 100% capacity (water level at maximum level in pre-treatment chamber). If future water levels are below this mark when system is at 100% capacity this is an indicator that maintenance to the pre -filter cartridges may be needed. • Finalize inspection report for analysis by the maintenance manager to determine if maintenance is required. www.modularwetlands.com WETLANDS Maintenance Indicators Based upon observations made during inspection, maintenance of the system may be required based on the following indicators: • Missing or damaged internal components or cartridges. • Obstructions in the system or its inlet or outlet. • Excessive accumulation of floatables in the pre-treatment chamber in which the length and width of the chamber is fully impacted more than 18". • Excessive accumulation of sediment in the pre-treatment chamber of more than 6" in depth. www.modularwetlands.com WETLANDS • Excessive accumulation of sediment on the BioMediaGREEN media housed within the pre- filter cartridges. The following chart shows photos of the condition of the BioMediaGREEN contained within the pre -filter cartridges. When media is more than 85% clogged replacement is required. New BioMediaGREEN 0% -- Percent Clogged -- 100% • Overgrown vegetation. Exhausted BioMediaGREEN • Water level in discharge chamber during 100% operating capacity (pre-treatment chamber water level at max height) is lower than the watermark by 20%. www.modularwetiands.com WETLANDS Inspection Notes 1. Following maintenance and/or inspection, it is recommended the maintenance operator prepare a maintenance/inspection record. The record should include any maintenance activities performed, amount and description of debris collected, and condition of the system and its various filter mechanisms. 2. The owner should keep maintenance/inspection record(s) for a minimum of five years from the date of maintenance. These records should be made available to the governing municipality for inspection upon request at any time. 3. Transport all debris, trash, organics and sediments to approved facility for disposal in accordance with local and state requirements. 4. Entry into chambers may require confined space training based on state and local regulations. 5. No fertilizer shall be used in the Biofiltration Chamber. 6. Irrigation should be provided as recommended by manufacturer and/or landscape architect. Amount of irrigation required is dependent on plant species. Some plants may not require irrigation after initial establishment. www.modularwetlands.com WETLANDS Maintenance Guidelines for Modular Wetland System - Linear Maintenance Summary o Remove Sediment from Pre -Treatment Chamber - average maintenance interval is 12 to 24 months. ■ (10 minute average service time). o Replace Pre -Filter Cartridge Media - average maintenance interval 12 to 24 months. ■ ( 90- 95 minute per cartridge average service time). o Trim Vegetation - average maintenance interval is 6 to 12 months. ■ ( Service time varies) . System Diagram Access to separation chamber and pre -filter cartridge Individual Media Filters Cartridge BioMediaGREEN kErlond D I A' OPre-treatment Chamber 0 Biofiltration Chamber O3 Discharge Chamber www.modularwetlands.com U Maintenance Overview WETLANDS The time has come to maintain your Modular Wetland System Linear (MWS Linear). To ensure successful and efficient maintenance on the system we recommend the following. The MWS Linear can be maintained by removing the access hatches over the systems various chambers. All necessary pre -maintenance steps must be carried out before maintenance occurs, especially traffic control and other safety measures to protect the inspector and near -by pedestrians from any dangers associated with an open access hatch or manhole. Once traffic control has been set up per local and state regulations and access covers have been safely opened the maintenance process can begin. It should be noted that some maintenance activities require confined space entry. All confined space requirements must be strictly followed before entry into the system. In addition the following is recommended: • Prepare the maintenance form by writing in the necessary information including project name, location, date & time, unit number and other info (see maintenance form). • Set up all appropriate safety and cleaning equipment. • Ensure traffic control is set up and properly positioned. • Prepare a pre -checks (OSHA, safety, confined space entry) are performed. Maintenance Equipment Following is a list of equipment required for maintenance of the MWS Linear: • Modular Wetland Maintenance Form • Manhole hook or appropriate tools to access hatches and covers • Protective clothing, flashlight and eye protection. • 7/16" open or closed ended wrench. • Vacuum assisted truck with pressure washer. • Replacement BioMediaGREEN for Pre -Filter Cartridges if required (order from manufacturer). low www.modularwetlands.com WETLANDS Maintenance Steps 1. Pre-treatment Chamber (bottom of chamber) A. Remove access hatch or manhole cover over pre-treatment chamber and position vacuum truck accordingly. B. With a pressure washer spray down pollutants accumulated on walls and pre -filter cartridges. C. Vacuum out Pre -Treatment Chamber and remove all accumulated pollutants including trash, debris and sediments. Be sure to vacuum the floor until pervious pavers are visible and clean. D. If Pre -Filter Cartridges require media replacement move onto step 2. If not, replace access hatch or manhole cover. Removal of access hatch to gain access below. Removal of trash, sediment and debris. Insertion of vacuum hose into separation chamber. Fully cleaned separation chamber. www.modularwetiands.com 2. Pre -Filter Cartridqes (attached to wall of pre-treatment chamber A. After finishing step 1 enter pre-treatment chamber. B. Unscrew the two bolts holding the lid on each cartridge filter and remove lid. A " TZ �= =1 Pre -filter cartridges with tops on. WETLANDS Inside cartridges showing media filters ready for replacement. C. Place the vacuum hose over each individual media filter to suck out filter media. Vacuuming out of media filters. D. Once filter media has been sucked use a pressure washer to spray down inside of the cartridge and it's containing media cages. Remove cleaned media cages and place to the side. Once removed the vacuum hose can be inserted into the cartridge to vacuum out any remaining material near the bottom of the cartridge. www.modularwetlands.com WETLANDS E. Reinstall media cages and fill with new media from manufacturer or outside supplier. Manufacturer will provide specification of media and sources to purchase. Utilize the manufacture provided refilling trey and place on top of cartridge. Fill trey with new bulk media and shake down into place. Using your hands slightly compact media into each filter cage. Once cages are full removed refilling trey and replace cartridge top ensuring bolts are properly tightened. Refilling trey for media replacement. Refilling trey on cartridge with bulk media. F. Exit pre-treatment chamber. Replace access hatch or manhole cover. 3. Biofiltration Chamber (middle vegetated chamber) A. In general, the biofiltration chamber is maintenance free with the exception of maintaining the vegetation. Using standard gardening tools properly trim back the vegetation to healthy levels. The MWS Linear utilizes vegetation similar to surrounding landscape areas therefore trim vegetation to match surrounding vegetation. If any plants have died replace plants with new ones: www.modularwetlands.com WETLANDS Inspection Notes 1. Following maintenance and/or inspection, it is recommended the maintenance operator prepare a maintenance/inspection record. The record should include any maintenance activities performed, amount and description of debris collected, and condition of the system and its various filter mechanisms. 2. The owner should keep maintenance/inspection record(s) for a minimum of five years from the date of maintenance. These records should be made available to the governing municipality for inspection upon request at any time. 3. Transport all debris, trash, organics and sediments to approved facility for disposal in accordance with local and state requirements. 4. Entry into chambers may require confined space training based on state and local regulations. 5. No fertilizer shall be used in the Biofiltration Chamber. 6. Irrigation should be provided as recommended by manufacturer and/or landscape architect. Amount of irrigation required is dependent on plant species. Some plants may not require irrigation after initial establishment. www.modularwetlands.com WETLANDS Inspection Form Modular Wetland System, Inc. P. 760.433-7640 F. 760-433-3176 E. Info@modularwetlands.com www.modularwetlands.com WETLANDS Maintenance Report Modular Wetland System, Inc. P. 760.433-7640 F. 760-433-3176 E. Info@modularwetlands.com www.modularwetlands.com No. 5 — Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed General Trash & Trash or debris which is located immediately No Trash or debris located Debris in front of the catch basin opening or is immediately in front of blocking inletting capacity of the basin by catch basin or on grate more than 10%. opening. Trash or debris (in the basin) that exceeds 60 No trash or debris in the percent of the sump depth as measured from catch basin. the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of six inches clearance from the debris surface to the invert of the lowest pipe. Trash or debris in any inlet or outlet pipe Inlet and outlet pipes free blocking more than 1/3 of its height. of trash or debris. Dead animals or vegetation that could No dead animals or generate odors that could cause complaints vegetation present within or dangerous gases (e.g., methane). the catch basin. Sediment Sediment (in the basin) that exceeds 60 No sediment in the catch percent of the sump depth as measured from basin the bottom of basin to invert of the lowest pipe into or out of the basin, but in no case less than a minimum of 6 inches clearance from the sediment surface to the invert of the lowest pipe. Structure Top slab has holes larger than 2 square Top slab is free of holes Damage to inches or cracks wider than 1/4 inch and cracks. Frame and/or Top Slab (Intent is to make sure no material is running into basin). Frame not sitting flush on top slab, i.e., Frame is sitting flush on separation of more than 3/4 inch of the frame the riser rings or top slab from the top slab. Frame not securely and firmly attached. attached Fractures or Maintenance person judges that structure is Basin replaced or repaired Cracks in unsound. to design standards. Basin Walls/ Bottom Grout fillet has separated or cracked wider Pipe is regrouted and than 1/2 inch and longer than 1 foot at the secure at basin wall. joint of any inlet/outlet pipe or any evidence of soil particles entering catch basin through cracks. Settlement/ If failure of basin has created a safety, Basin replaced or repaired Misalignment function, or design problem. to design standards. Vegetation Vegetation growing across and blocking more No vegetation blocking than 10% of the basin opening. opening to basin. Vegetation growing in inlet/outlet pipe joints No vegetation or root that is more than six inches tall and less than growth present. six inches apart. Contamination See "Detention Ponds" (No. 1). No pollution present. and Pollution Volume V — Runoff Treatment BMPs — December 2014 4-38 No. 5 — Catch Basins Maintenance Defect Conditions When Maintenance is Needed Results Expected When Component Maintenance is performed Catch Basin Cover Not in Cover is missing or only partially in place. Catch basin cover is Cover Place Any open catch basin requires maintenance. closed Locking Mechanism cannot be opened by one Mechanism opens with Mechanism maintenance person with proper tools. Bolts proper tools. Not Working into frame have less than 1/2 inch of thread. Cover Difficult One maintenance person cannot remove lid Cover can be removed by to Remove after applying normal lifting pressure. one maintenance person. (Intent is keep cover from sealing off access to maintenance.) Ladder Ladder Rungs Ladder is unsafe due to missing rungs, not Ladder meets design Unsafe securely attached to basin wall, standards and allows misalignment, rust, cracks, or sharp edges. maintenance person safe access. Metal Grates Grate opening Grate with opening wider than 7/8 inch. Grate opening meets (If Applicable) Unsafe design standards. Trash and Trash and debris that is blocking more than Grate free of trash and Debris 20% of grate surface inletting capacity. debris. Damaged or Grate missing or broken member(s) of the Grate is in place and Missing. grate. meets design standards. N*-Q — Debris Barriers (e.g., Trash Racks) Maintenance Defect Condition When Maintenance is Results Expected W Components Needed Maintenance i rformed General Trash an Trash or debris that is plugging more Bar " cleared to design flow Debris 20% of the openings in the barrier. apacity. Metal Damaged/ Bars are be ut of shape mo an 3 Bars in place with no bends more Missing inches. than 3/4 inch. Bars. Bars ar ssing or entire barrier Bars in place according to design. g. Bars are loose and rust is causing 50% Barrie laced or repaired to deterioration to any part of barrier. design stan s. Inlet/Outlet Debris barrier missing or not attached to Barrier firmly attache i e Pipe pipe Volume V — Runoff Treatment BMPs — December 2014 4-39 No. 18 — Catchbasin Inserts Maintenance Defect Conditions When Maintenance is Results Expected When Component Needed Maintenance is Performed General Sediment When sediment forms a cap over the No sediment cap on the insert Accumulation insert media of the insert and/or unit. media and its unit. Trash and Trash and debris accumulates on insert Trash and debris removed Debris unit creating a blockage/restriction. from insert unit. Runoff freely Accumulation flows into catch basin. Media Insert Not Effluent water from media insert has a Effluent water from media Removing Oil visible sheen. insert is free of oils and has no visible sheen. Media Insert Catch basin insert is saturated with water Remove and replace media Water Saturated and no longer has the capacity to insert absorb. Media Insert -Oil Media oil saturated due to petroleum spill Remove and replace media Saturated that drains into catch basin. insert. Media Insert Use Media has been used beyond the typical Remove and replace media at Beyond Normal average life of media insert product. regular intervals, depending on Product Life insert product. Volume V — Runoff Treatment BMPs — December 2014 4-51 S406 MR* for Streets/ Highways Applicable BMPs: • Select de and anti-icers that cause the least erse environmental i act. Apply only as needed using mi um quantities. • Wher acticable use roadway d ' ers, such as calcium magnesium acetate, p acetate, or filar materials, that cause less adverse environment�si�m act th rea, and sodium chloride. • Store and transfer nd anti -icing materials on an impervious containment p n acc ance with BMP Storage or Transfer Outside o olid Raw Ma als By -Products, or Finished Products in this ume. • eep/clean up accumulated de and i-icing materials and grit from roads as soon as possible after the roads ace clears. Recommended Additional BMPs • Intensify roadway cleaning in early spring to help re ve particulates from road surfaces. • Include limits on toxic metals in the specifications for de/anti-' rs. S407 BMPs for Dust Control at Disturbed Land Areas and Unpaved Roadways and Parking Lots Description of Pollutant Sources: Dust can cause air and water pollution problems particularly at demolition sites and in and areas where reduced rainfall exposes soil particles to transport by air. Pollutant Control Approach: Minimize dust generation and apply environmentally friendly and government approved dust suppressant chemicals, if necessary. Applicable Operational BMPs: • Sprinkle or wet down soil or dust with water as long as it does not result in a wastewater discharge. • Use only local and/or state government approved dust suppressant chemicals such as those listed in Ecology Publication #96-433, Techniques for Dust Prevention and Suppression. • Avoid excessive and repeated applications of dust suppressant chemicals. Time the application of dust suppressants to avoid or minimize their wash -off by rainfall or human activity such as irrigation. • Apply stormwater containment to prevent the conveyance of sediment into storm drains or receiving waters. Volume IV - Source Control BMPs — December 2014 2-15 S408 • Ecology prohibits the use of motor oil for dust control. Take care when using lignin derivatives and other high BOD chemicals in areas susceptible to contaminating surface water or ground water. Consult with Ecology and the local permitting authority on discharge permit requirements if the dust suppression process results in a wastewater discharge to the ground, ground water, storm drain, or surface water. Recommended Additional Operational BMPs for Roadways and Other Trafficked Areas: • Consider limiting use of off -road recreational vehicles on dust generating land. • Consider graveling or paving unpaved permanent roads and other trafficked areas at municipal, commercial, and industrial areas. • Consider paving or stabilizing shoulders of paved roads with gravel, vegetation, or local government approved chemicals. • Encourage use of alternate paved routes, if available. • Vacuum sweep fine dirt and skid control materials from paved roads soon after winter weather ends or when needed. • Consider using pre -washed traction sand to reduce dust emissions. Additional Recommended Operational BMPs for Dust Generating Areas: • Prepare a dust control plan. Helpful references include: Control of Open Fugitive Dust Sources (EPA-450/3-88-088), and Fugitive Dust Background Document and Technical Information Document for Best Available Control Measures (EPA-450/2-92-004). • Limit exposure of soil (dust source) as much as feasible. • Stabilize dust -generating soil by growing and maintaining vegetation, mulching, topsoiling, and/or applying stone, sand, or gravel. • Apply windbreaks in the soil such as trees, board fences, tarp curtains, bales of hay, etc. Dust Control at Manufacturing Areas tion of Pollutant Sources: can genera nsiderable amounts exhaust systems. ce n powdered materials _cawe s era idustrial real handling activities at is typically removed using concrete products and handling dust. Particulate materials that can cause air po 2>lierinclude grain du wdust, coal, gravel, crushed rock, ceme , d boiler fly ash. Air emissions ca taminate stormwater. The <ective of this BMP is to reduce the stormwater p nts caused by dust generation and control. Volume IV - Source Control BMPs — December 2014 2-16 Applicable Operational BMPs: • Eliminate unpermitted wastewater discharges to water, or surface water. , • Convey unpermitted discharges to a local sewer authority, or to other ap] Obtain appropriate state and local RecXnmended Additional Operati indus ' 1 facilities, conduct a survey to storm Zkains and to surface water/ sewer, ground if allowed by the for these discharges. BMPs: At commercial and wastewater discharge connections follows: • Conduct Xleld survey of bu' dings, particularly older buildings, and other Indust ' 1 areas to to to storm drains from buildings and paved surfaces. Note here thgAe join the public storm drain(s). • During non -storm r conditions inspect each storm drain for non- 0 dischar�allitted rd the locations of all non -stormwater discharges. Incl e discharges. • If useful, pre re a map of Nkch location of orm sewers, sani unpermit d discharges. Aerial such a iping schematics to fide and ow these on the map. Co an ysis tests to detect connecti .g., process water and stormw inspections of the storm drains area. Show on the map the known sewers, and permitted and p tos may be useful. Check records nti own side sewer connections Compare the observed locations of connections 'th the information on the map and revise the map accordingly. Note s ect connections that are inconsistent with the field survey. • Identify all connections to storm sewers or to surface wai'$f and take the actions specified above as applicable BMPs. S411 BMPs for Landscaping and Lawn/ Vegetation Management Description of Pollutant Sources: Landscaping can include grading, soil transfer, vegetation removal, pesticide and fertilizer applications, and watering. Stormwater contaminants include toxic organic compounds, heavy metals, oils, total suspended solids, coliform bacteria, fertilizers, and pesticides. Lawn and vegetation management can include control of objectionable weeds, insects, mold, bacteria, and other pests with pesticides. Examples include weed control on golf course lawns, access roads, and utility corridors and during landscaping; sap stain and insect control on lumber and logs; rooftop moss removal; killing nuisance rodents; fungicide application to patio decks, and residential lawn/plant care. It is possible to Volume IV - Source Control BMPs — December 2014 2-21 release toxic pesticides such as pentachlorophenol, carbamates, and organometallics to the environment by leaching and dripping from treated parts, container leaks, product misuse, and outside storage of pesticide contaminated materials and equipment. Poor management of the vegetation and poor application of pesticides or fertilizers can cause appreciable stormwater contamination. Pollutant Control Approach: Control of fertilizer and pesticide applications, soil erosion, and site debris to prevent contamination of stormwater. Develop and implement an Integrated Pest Management Plan (IPM) and use pesticides only as a last resort. Carefully apply pesticides/ herbicides, in accordance with label instructions. Maintain appropriate vegetation, with proper fertilizer application where practicable, to control erosion and the discharge of stormwater pollutants. Where practicable grow plant species appropriate for the site, or adjust the soil properties of the subject site to grow desired plant species. Applicable Operational BMPs for Landscaping: • Install engineered soil/landscape systems to improve the infiltration and regulation of stormwater in landscaped areas. Do not dispose of collected vegetation into waterways or storm sewer systems. Recommended Additional Operational BMPs for Landscaping: • Conduct mulch -mowing whenever practicable • Dispose of grass clippings, leaves, sticks, or other collected vegetation, by composting, if feasible. • Use mulch or other erosion control measures on soils exposed for more than one week during the dry season or two days during the rainy season. • Store and maintain appropriate oil and chemical spill cleanup materials in readily accessible locations when using oil or other chemicals. Ensure that employees are familiar with proper spill cleanup procedures. • Till fertilizers into the soil rather than dumping or broadcasting onto the surface. Determine the proper fertilizer application rate for the types of soil and vegetation encountered. • Till a topsoil mix or composted organic material into the soil to create a well -mixed transition layer that encourages deeper root systems and drought -resistant plants. • Use manual and/or mechanical methods of vegetation removal rather than applying herbicides, where practical. Volume IV - Source Control BMPs — December 2014 2-22 Applicable Operational BMPs for the Use of Pesticides: • Develop and implement an IPM (See section on IPM in Applicable Operational BMPs for Vegetation Many ems) and use pesticides only as a last resort. • Implement a pesticide -use plan and include at a minimum: a list of selected pesticides and their specific uses; brands, formulations, application methods and quantities to be used; equipment use and maintenance procedures; safety, storage, and disposal methods; and monitoring, record keeping, and public notice procedures. All procedures shall conform to the requirements of Chapter 17.21 RCW and Chapter 16-228 WAC (Appendix IV-D R.7). • Choose the least toxic pesticide available that is capable of reducing the infestation to acceptable levels. The pesticide should readily degrade in the environment and/or have properties that strongly bind it to the soil. Conduct any pest control activity at the life stage when the pest is most vulnerable. For example, if it is necessary to use a Bacillus thurin ig'ens application to control tent caterpillars, apply it to the material before the caterpillars cocoon or it will be ineffective. Any method used should be site -specific and not used wholesale over a wide area. • Apply the pesticide according to label directions. Do not apply pesticides in quantities that exceed manufacturer's instructions. • Mix the pesticides and clean the application equipment in an area where accidental spills will not enter surface or ground waters, and will not contaminate the soil. • Store pesticides in enclosed areas or in covered impervious containment. Do not discharge pesticide contaminated stormwater or spills/leaks of pesticides to storm sewers. Do not hose down the paved areas to a storm sewer or conveyance ditch. Store and maintain appropriate spill cleanup materials in a location known to all near the storage area. • Clean up any spilled pesticides. Keep pesticide contaminated waste materials in designated covered and contained areas. • The pesticide application equipment must be capable of immediate shutoff in the event of an emergency. • Spraying pesticides within 100 feet of open waters including wetlands, ponds, and rivers, streams, creeks, sloughs and any drainage ditch or channel that leads to open water may have additional regulatory requirements beyond just following the pesticide product label. Additional requirements may include: Obtaining a discharge permit from Ecology. Obtaining a permit from the local jurisdiction. Using an aquatic labeled pesticide. Volume IV - Source Control BMPs — December 2014 2-23 obtain a publication entitled "Suspended, Canceled, and Restricted Pesticides" which lists all restricted pesticides and the specific uses that are allowed. Applicable Operational BMPs for Vegetation Management: Use at least an eight -inch "topsoil' layer with at least 8 percent organic matter to provide a sufficient vegetation -growing medium. Amending existing landscapes and turf systems by increasing the percent organic matter and depth of topsoil can substantially improve the permeability of the soil, the disease and drought resistance of the vegetation, and reduce fertilizer demand. This reduces the demand for fertilizers, herbicides, and pesticides. Organic matter is the least water-soluble form of nutrients that can be added to the soil. Composted organic matter generally releases only between 2 and 10 percent of its total nitrogen annually, and this release corresponds closely to the plant growth cycle. Return natural plant debris and mulch to the soil, to continue recycling nutrients indefinitely. Select the appropriate turfgrass mixture for the climate and soil type. Certain tall fescues and rye grasses resist insect attack because the symbiotic endophytic fungi found naturally in their tissues repel or kill common leaf and stem -eating lawn insects. However, they do not, repel root -feeding lawn pests such as Crane Fly larvae, and are toxic to ruminants such as cattle and sheep. The fungus causes no known adverse effects to the host plant or to humans. Endophytic grasses are commercially available; use them in areas such as parks or golf courses where grazing does not occur. Local agricultural or gardening resources such as Washington State University Extension office can offer advice on which types of grass are best suited to the area and soil type. • Use the following seeding and planting BMPs, or equivalent BMPs to obtain information on grass mixtures, temporary and permanent seeding procedures, maintenance of a recently planted area, and fertilizer application rates: Temporary and Permanent Seeding, Mulching, Plastic Covering, and Sodding as described in Volume II. Adjusting the soil properties of the subject site can assist in selection of desired plant species. For example, design a constructed wetland to resist the invasion of reed canary grass by layering specific strata of organic matters (e.g., composted forest product residuals) and creating a mildly acidic pH and carbon -rich soil medium. Consult a soil restoration specialist for site -specific conditions. • Aerate lawns regularly in areas of heavy use where the soil tends to become compacted. Conduct aeration while the grasses in the lawn are growing most vigorously. Remove layers of thatch greater than 3/4-inch deep. Volume IV - Source Control BMPs — December 2014 2-25 Mowing is a stress -creating activity for turfgrass. Grass decreases its productivity when mown too short and there is less growth of roots and rhizomes. The turf becomes less tolerant of environmental stresses, more disease prone and more reliant on outside means such as pesticides, fertilizers, and irrigation to remain healthy. Set the mowing height at the highest acceptable level and mow at times and intervals designed to minimize stress on the turf. Generally mowing only 1/3 of the grass blade height will prevent stressing the turf. Irrigation: The depth from which a plant normally extracts water depends on the rooting depth of the plant. Appropriately irrigated lawn grasses normally root in the top 6 to 12 inches of soil; lawns irrigated on a daily basis often root only in the top 1 inch of soil. Improper irrigation can encourage pest problems, leach nutrients, and make a lawn completely dependent on artificial watering. The amount of water applied depends on the normal rooting depth of the turfgrass species used, the available water holding capacity of the soil, and the efficiency of the irrigation system. Consult with the local water utility, Conservation District, or Cooperative Extension office to help determine optimum irrigation practices. Fertilizer Management: Turfgrass is most responsive to nitrogen fertilization, followed by potassium and phosphorus. Fertilization needs vary by site depending on plant, soil, and climatic conditions. Evaluation of soil nutrient levels through regular testing ensures the best possible efficiency and economy of fertilization. For details on soils testing, contact the local Conservation District, a soils testing professional, or a Washington State University Extension office. Apply fertilizers in amounts appropriate for the target vegetation and at the time of year that minimizes losses to surface and ground waters. Do not fertilize when the soil is dry. Alternatively, do not apply fertilizers within three days prior to predicted rainfall. The longer the period between fertilizer application and either rainfall or irrigation, the less fertilizer runoff occurs. Use slow release fertilizers such as methylene urea, IDBU, or resin coated fertilizers when appropriate, generally in the spring. Use of slow release fertilizers is especially important in areas with sandy or gravelly soils. • Time the fertilizer application to periods of maximum plant uptake. Ecology generally recommends application in the fall and spring, although Washington State University turf specialists recommend four fertilizer applications per year. Volume IV - Source Control BMPs — December 2014 2-26 Treatment BMPs: Install biofiltra les er strips — (See Chapter 9, Volume V) to treat roadside ere cticable and use engineered topsoils w necessary to maintain adequa tation. These systems can improve infiltration and stormwater pollutant con t ream of roadside ditches. S417 BMPs for Maintenance of Stormwater Drainage and Treatment Systems Description of Pollutant Sources: Facilities include roadside catch basins on arterials and within residential areas, conveyance systems, detention facilities such as ponds and vaults, oil/water separators, biofilters, settling basins, infiltration systems, and all other types of stormwater treatment systems presented in Volume V. Oil and grease, hydrocarbons, debris, heavy metals, sediments and contaminated water are found in catch basins, oil and water separators, settling basins, etc. Pollutant Control Approach: Provide maintenance and cleaning of debris, sediments, and oil from stormwater collection, conveyance, and treatment systems to obtain proper operation. Applicable Operational BMPs: Maintain stormwater treatment facilities per the operations and maintenance (O&M) procedures presented in Section 4.6 of Volume V in addition to the following BMPs: • Inspect and clean treatment BMPs, conveyance systems, and catch basins as needed, and determine necessary O&M improvements. • Promptly repair any deterioration threatening the structural integrity of stormwater facilities. These include replacement of clean -out gates, catch basin lids, and rock in emergency spillways. • Ensure adequacy of storm sewer capacities and prevent heavy sediment discharges to the sewer system. • Regularly remove debris and sludge from BMPs used for peak -rate control, treatment, etc. and discharge to a sanitary sewer if approved by the sewer authority, or truck to an appropriate local or state government approved disposal site. • Clean catch basins when the depth of deposits reaches 60 percent of the sump depth as measured from the bottom of basin to the invert of the lowest pipe into or out of the basin. However, in no case should there be less than six inches clearance from the debris surface to the invert of the lowest pipe. Some catch basins (for example, WSDOT Type 1 L basins) may have as little as 12 inches sediment storage below the invert. These catch basins need frequent inspection and cleaning to prevent scouring. Where these catch basins are part of a stormwater collection and treatment system, the system Volume IV - Source Control BMPs — December 2014 2-3 7 owner/operator may choose to concentrate maintenance efforts on downstream control devices as part of a systems approach. • Clean woody debris in a catch basin as frequently as needed to ensure proper operation of the catchbasin. • Post warning signs; "Dump No Waste - Drains to Ground Water," "Streams," "Lakes," or emboss on or adjacent to all storm drain inlets where possible. • Disposal of sediments and liquids from the catch basins must comply with "Recommendations for Management of Street Wastes" described in Appendix IV-G of this volume. Additional Applicable BMPs: Select additional applicable BMPs from this chapter depending on the pollutant sources and activities conducted at the facility. Those BMPs include: • S425 BMPs for Soil Erosion and Sediment Control at Industrial Sites • S427 BMPs for Storage of Liquid, Food Waste, or Dangerous Waste Containers • S406 BMPs for Spills of Oil and Hazardous Substances • 5410 BMPs for Illicit Connections to Storm Drains • S430 BMPs for Urban Streets BMPs for Manufacturing Activities - Outside Description of Pollutant Sources: Manufacturing pollu t sources include outside process areas, stack emissions, and ar s where manufacturing activity has taken place in the past d significant exposed llutant materials remain. Poll ' n Control Approach: Cover an ontain outside manufacturing and prey stormwater run-on and c amination, where feasible. Applicable • Sweep paved stormwater. • Alter the BMP: ly, as needed, to prevent contamination of by elimiXing or minimizing the contamination of AppKable Structural Source Co of BMPs: Enclose the activity e Figure 2.2.6): If possible, enclose manufacturing activity in a • Cover the activity and connect floor drains to a s tary sewer, if approved by the local sewer authority. Berm or slop e floor as a needed to prevent drainage of pollutants to outside are i re 2.2.7) Volume IV - Source Control BMPs — December 2014 2-38 Disc ar ' ation System PD at e uirements, Ecology, March 2011,websi .wa. ov/biblio/94146.html. Apply the B guidance�docu!5enCo scr 1 recycling facilities J.depending on the pollutant sources existing at those ac S424 BMPs for Roof/ Building Drains at Manufacturing and Commercial Buildings Description of Pollutant Sources: Stormwater runoff from roofs and sides of manufacturing and commercial buildings can be sources of pollutants caused by leaching of roofing materials, building vents, and other air emission sources. Research has identified vapors and entrained liquid and solid droplets/particles as potential pollutants in roof/building runoff. Metals, solvents, acidic/alkaline pH, BOD, and organics, are some of the pollutant constituents identified. Ecology has performed a study on zinc in industrial stormwater. The study is presented in Ecology Publication 08-10-025 Suggested Practices to reduce Zinc Concentrations in Industrial Stormwater Discharges, website: http://www.ecy.wa.gov/biblio/0810025.html. The user should refer to this document for more details on addressing zinc in stormwater. Pollutant Control Approach: Evaluate the potential sources of stormwater pollutants and apply source control BMPs where feasible. Applicable Operational Source Control BMPs: • If leachates and/or emissions from buildings are suspected sources of stormwater pollutants, then sample and analyze the Stormwater draining from the building. • Sweep the area routinely to remove any zinc residuals. If a roof/building stormwater pollutant source is identified, implement appropriate source control measures such as air pollution control equipment, selection of materials, operational changes, material recycle, process changes, etc. Applicable Structural Source Control BMPs: Paint/coat the galvanized surfaces as described in Ecology Publication # 08-10-025. Applicable Treatment BMPs: Treat runoff from roofs to the appropriate level. The facility may use enhanced treatment BMPs as described in Volume V of the SWMMWW. Some facilities regulated by the Industrial Stormwater General Permit, or local jurisdiction, may have requirements than cannot be achieved with enhanced treatment BMPs. In these cases, additional treatment measures may be required. A treatment method for meeting stringent requirements such as Chitosan-Enhanced Sand Filtration may be appropriate. Volume IV - Source Control BMPs — December 2014 2-46 Port of Edmonds Admin Building - CG 421160.20 Drainage Report April 01, 2022 Section VII, Page 5 SAMPLE ACTIVITY LOG DATE FACILITY MAINTENANCE PERFORMED RESULTS / NOTES 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph.425.778.8500 1 f.425.778.5536 www.cgengineering.com