ARCHIVED REPORTS_2001_2 - Laserfiche WebLink

Home Browse Search

C� hour, 1,000 -year storm event. A computer program developed by Advanced Engineering Software was used to compute the run-off. The hydrology study map indicating drainage sub -areas and discharge points and calculations for on site and off-site flows is presented on Drawing 10 of the JTD. A summary of the peak discharge rates are included in the hydrology study calculations included in Appendix G of the JTD. 3.6.1.2 PROPOSED FINAL DRAINAGE CONTROL SYSTEM The proposed final drainage control system for the Forward Landfill is shown on Drawing 9 of the JTD. The final surface area of the landfill decks will be graded at a minimum three percent gradient to prevent ponding and promote lateral runoff. The proposed final drainage control system will include exterior slope downdrains, engineered deck area gradients anddrainage,b,erms,..deck.inlets, bench drains and inlets, perimeter trapezoidal channels, and sedimentation basins. Drainage details are presented in Drawing 7 of the JTD. Some of 2the interim drainage control features may be utilized as part of the final drainage control system for the site. 3.6.2 SOIL LOSS ANALYSIS The Universal Soil Loss Equation (USLE) was used to evaluate potential soil losses within the watershed boundary of the Forward Landfill site. The USLE was initially intended for analysis of meadows and cropland soil loss. However, with certain engineered assumptions, it can be applied to soil cover over landfills. The USLE is: A = RKLSCP where A = average soil loss, in tons/acre R = rainfall and run-off erosivity index K = soil erodibility factor, tons/acre L = slope -length factor S = slope -steepness factor C = cover -management factor P = practice factor Forward Landfill PCPCMP 3-9 L:\Allied\2000.193\Reports\FinaIPCPCMP:FL-sec3: 8/20/01 BRYAN A. STIRRAT & ASSOCIATES