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5. SOURCE CONTROL <br /> This project proposes to construct a new , yse IV <br /> of the 2014 DOE Stormwater Management ManualSFRdetached was reviewedgarage forand drivewa specific BM.PsVolum required <br /> for this type of land-use. None of the activities or land uses contained in any of the chapters <br /> in Volume IV applies to this project. Therefore, no site/development specific source control <br /> BMPs are required for this project. <br /> 6. PRESERVATION OF NATURAL DRAINAGE SYSTEM <br /> By not grading or compacting the pervious and amended surfaces to remain after <br /> construction in the area of disturbance a maximum amount of site runoff from the developed <br /> project will be absorbed and infiltrated into the existing on-site soils. This will mimic the <br /> existing conditions by maintaining the existing direction and condition of flow from this site. <br /> 7. ON-SITE STORMWATER MANAGEMENT <br /> List #2 in the SWMM volume 1 section 2.5.6 provides multiple BMP options for runoff <br /> management, conveyance BMPs and Discharge BMPs. Each option was reviewed for this <br /> project and the most suitable was selected. <br /> Standard Project Runoff Manage Options <br /> Lawn and Landscaped Areas: <br /> 1. Post-Construction Soil Quality and Depth: Required <br /> Roofs: <br /> 1. Full Dispersion: Not feasible due to not having 65% preserved vegetation. <br /> 2. Downspout Infiltration Systems: As mentioned in Section 2 of this report, on- <br /> site soils were found to be sandy loam underlain by fine sand with a depth to <br /> water table of approximately 36 inches. Therefore, infiltration is feasible and <br /> is the selected BMP for this project. <br /> The roof surfaces shall be infiltrated using infiltration trenches. According to <br /> the DOE SWMMWW, a 2-foot-wide infiltration trench installed in soil <br /> classified as 'fine sand' shall be sized with a length of 75 feet per 1,000 sf of <br /> contributing roof area. For a total garage roof area of approximately 994 sf, <br /> the required trench area is 149 sf. Therefore, to fit the available space, a <br /> 25'x6' infiltration trench shall be used to infiltrate the garage roof area for a <br /> total trench area of 150 sf. For a total SFR roof area of 2,679, the required <br /> trench area is 402 sf. To fit the available space and keep the infiltration <br /> trenches as narrow as possible, three 6-foot wide infiltration trenches shall <br /> be used to infiltrate the entire SFR roof area runoff. Trench#1 will be 18 feet <br /> long, trench #2 will be 34 feet long, and trench #3 will be 16 feet long for a <br /> total trench area of 408 sf. <br /> Fogg-LEXAR SLDS 19-0506 <br /> July 2019 <br /> Revised:September 2019 Page 9 <br />