Laserfiche WebLink
5. SOURCE CONTROL <br /> This project proposes to construct a new SFR and driveway. Volume IV of the 2014 DOE <br /> Stormwater Management Manual was reviewed for specific BMPs required for this type of <br /> land-use. None of the activities or land uses contained in any of the chapters in Volume IV <br /> applies to this project. Therefore, no'site/development specific source°control BMPs are <br /> 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 Management 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-site soils <br /> were found to be silty fine to medium sands with no water table encountered to a <br /> depth of 6 feet. Therefore, infiltration is feasible and is the selected BMP for this <br /> project. <br /> The roof surfaces shall be infiltrated using an infiltration trench per BMP T5.10A. <br /> According to 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 SFR roof area of approximately 4,542 sf, the <br /> required trench area is 681 sf. Therefore, to infiltrate all roof runoff, a 14'x50' <br /> infiltration trench shall be used for a total trench area of 700 sf. Two perforated <br /> pipe laterals shall be installed within the trench, spaced 7 feet apart on-center to <br /> distribute the runoff effectively into the trench. <br /> 3. Bioretention/Rain Gardens: Higher priority BMP selected. <br /> 4. Downspout Dispersion: Higher priority BMP selected. <br /> McCann SFR 19-0913 <br /> September 2019 <br /> Revised:January 2020 Page 9 <br />