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AD SYSTEMS EXPANSION EVERETT,WA <br /> The BMPs in List#1 (below) was evaluated for feasibility for each type of surface. The first BMP that <br /> was determined feasible was selected for on-site use. <br /> List#1 BMPs: <br /> Lawn and Landscaped Areas: <br /> • Post-Construction Soil Quality and Depth:Determined feasible. <br /> Roofs: <br /> • Full Dispersion: Determined infeasible due to the vegetated flowpath setbacks from the <br /> existing and proposed pavements, building and property line, which leaves an <br /> insufficient on-site area to provide the required vegetated pervious area. <br /> • Bioretention:Determined infeasible due to shallow impermeable layer and perched <br /> groundwater <br /> • Downspout Dispersion Systems: Determined infeasible, as there is insufficient area to <br /> provide the required vegetated flowpath on-site with the required vegetated flowpath <br /> setbacks from the existing and proposed pavements and property line. <br /> • Perforated Stub-out Connections:Infiltration on this site is not recommended due to <br /> reasonable concerns regarding shallow impermeable layer and perched groundwater <br /> Other Hard Surfaces: <br /> • Full Dispersion:Determined infeasible, as there is insufficient area to provide the <br /> required vegetated flowpath on-site with the required vegetated flowpath setbacks from <br /> the existing and proposed pavements and property lines. <br /> • Permeable pavement:Infiltration on this site is not recommended due to reasonable <br /> concerns regarding shallow impermeable layer and perched groundwater. <br /> • Bioretention BMPs:Infiltration on this site is not recommended due to reasonable concerns <br /> regarding shallow impermeable layout and perched groundwater. <br /> • Sheet Flow Dispersion:Determined infeasible, as there is insufficient area to provide the <br /> required vegetated flowpath on-site with the required vegetated flowpath setbacks from <br /> the existing and proposed pavements and property line. <br /> NOVEMBER 20, 2017 STORMWATER DRAINAGE SUMMARY PAGE 8 <br />