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0 3.6.1.2 PROPOSED FINAL DRAINAGE CONTROL SYSTEM <br />The proposed final drainage control system for the Forward Landfill Stage IA <br />is shown on Drawing Sheets 3, 4, 5, 6 and 7. Runoff is directed to the natural <br />drainage course. <br />The proposed final drainage control system for Stage IA will include exterior <br />slope AC downdrains, and topdeck drainage berms, deck inlets, bench drains <br />and inlets. Runoff is directed to the natural drainage course. Stage IA <br />drainage improvements will also include placement of additional soils along <br />the perimeter road to increase the elevation of the road above historic and <br />potential flood levels. Drainage details are presented in Drawing Sheets D-1, <br />D-2, and D-3. <br />3.6.2 SOIL LOSS ANALYSIS <br />The Universal Soil Loss Equation (USLE) was used to evaluate potential soil <br />losses within the watershed boundary of the Forward Landfill site. The USLE <br />was initially intended for analysis of meadows and cropland soil loss. <br />However, with certain engineered assumptions, it can be applied to soil cover <br />over landfills. <br />The USLE is: <br />A = RKLSCP <br />where A = average soil loss, in tons/acre <br />R = rainfall and run-off erosivity index <br />K = soil erodibility factor, tons/acre <br />L = slope -length factor <br />S = slope -steepness factor <br />C = cover -management factor <br />P = practice factor <br />The soil loss analysis performed is based on a "closed landfill' condition as <br />required by CCR Title 27, and for a post final closure construction condition to <br />estimate sediment amounts as a basis for sizing the sedimentation basins. <br />At closure, the potential soil loss is minimal because the landfill will have a <br />compacted final cover, an erosion control surface of vegetation and a storm <br />drain system installed which all contribute to controlling soil erosion. The <br />landfill soil loss analysis data is presented in Appendix F. <br />Forward Landfill PFCPCMP 3-12 <br />Z:\PROJECTS\Allied Waste\Forward\Reference Files Prior JTD\June 05 Stage IA Partial FCPCMP\FL-sec3.doc: 6/16/2008 <br />