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5. SOURCE CONTROL <br /> This project proposes to install a manufactured home in place of an existing SFR. Volume <br /> IV of the 2014 DOE Stormwater Management Manual was reviewed for specific BMPs <br /> required for this type of land-use. None of the activities or land uses contained in any of the <br /> chapters in Volume IV applies to this project. Therefore, no site/development specific <br /> source control BMPs are required for this project. <br /> 6. PRESERVATION OF NATURAL DRAINAGE SYSTEM <br /> By grading and then amending the site soils in the area of disturbance while ensuring the <br /> proposed grades maintain slopes in same direction as the current conditions, this will allow <br /> the site to absorb some of the future runoff and provide sheet flow of runoff to the south- <br /> southeast. This will mimic the existing conditions by maintaining the existing direction and <br /> condition of flow from this site. <br /> 7. ON-SITE STORMWATER MANAGEMENT <br /> List #1 in the SWMM Volume 1 section 2.5.5 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. 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 the site not containing at least 65% native <br /> vegetation. <br /> 2. Downspout Infiltration Systems: As mentioned in,Section 2 of this report,. the soil <br /> analysis on site found gravelly sandy loam with mottling at approximately 18 inches <br /> and hardpan at approximately 25 inches below grade. Therefore, infiltration is <br /> infeasible due to the shallow depth to seasonal water table and hardpan, with less <br /> than 36 inches of available permeable soils. <br /> 3. Bioretention/Rain Gardens: Not feasible (see above). <br /> 4. Downspout Dispersion: Minimum flow paths can be provided, so downspout <br /> dispersion is feasible and selected for this project. Splash blocks shall be used to <br /> disperse all proposed roof runoff. This project proposes to construct approximately <br /> 2,178 sf of new roof surfaces. According to the DOE Manual, a maximum of 700 sf <br /> of roof surface may drain to each splash block. Therefore, a minimum of 4 splash <br /> blocks shall be used to disperse runoff from the new roof. <br /> 5.. Perforated Stub-Out Connections: Higher priority BMP selected. <br /> Lucas MFH 20-0715 <br /> March"2021 Page 9 <br />