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For onsite stormwater management (MR#5) list # 2 was used per Vol 1 section 2.5.5 of the <br /> SWMMWW. Full dispersion was considered first however it was deemed infeasible due to <br /> the lack of native vegetation. Downspout full infiltration was deemed infeasible due to the <br /> presence of iron oxide deposits at shallow depths, indicating poor infiltrating soils and a <br /> shallow low permeable layer. Please refer to the Geotechnical Report for more details. <br /> Bioretention was deemed infeasible as the site lacks the necessary area to accommodate <br /> infiltration facilities within the required setbacks. Downspout Dispersion is infeasible <br /> because the site cannot provide the required vegetated flow paths. Perforated stub out <br /> connections are also not feasible due to the iron oxide deposits found at shallow depths. <br /> The runoff from the roof will be tight lined to a detention system on the east side of the <br /> project to continue to the City's combined sewer system. <br /> 1. The purpose of this SWPPP is to describe the proposed construction <br /> activities and all temporary and permanent erosion and sediment <br /> control (TESC) measures, pollution prevention measures, <br /> inspection/monitoring activities, and recordkeeping that will be <br /> implemented during the proposed construction project. The <br /> objectives of the SWPPP are to: <br /> 2. Implement Best Management Practices (BMPs) to prevent erosion <br /> and sedimentation, and to identify, reduce, eliminate or prevent <br /> stormwater contamination and water pollution from construction <br /> activity. <br /> 3. Prevent violations of surface water quality, ground water quality, or <br /> sediment management standards. <br /> 4. Prevent, during the construction phase, adverse water quality <br /> impacts including impacts on beneficial uses of the receiving water <br /> by controlling peak flow rates and volumes of stormwater runoff at <br /> the Permittee's outfalls and downstream of the outfalls. <br /> 5. This SWPPP was prepared using the Ecology SWPPP Template. <br /> This SWPPP was prepared based on the requirements set forth in the <br /> Construction Stormwater General Permit and in the Stormwater <br /> Management Manual for Western Washington (SWMMWW 2014). <br /> The 13 BMP Elements <br /> Insight Engineering Co. -Stormwater Site Plan 3/25/2021 <br /> - 16- <br />