COMPLIANCE INFO_JTD 7-14-25 - Laserfiche WebLink

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North County RC&SL Page 27 of 64 Public Works/Solid Waste Joint Technical Document County of San Joaquin – Revised July 14, 2025 and Plate 6). Leachate seepage from the landfill is monitored at five unsaturated zone points. Off-site migration of LFG is monitored at perimeter migration monitoring wells (Plate 6) in accordance with the Methane Monitoring Program (Appendix I). 5.8 FINAL GRADING PLAN The proposed final landfill grading plan reflects the maximum fill elevation of 320 ft MSL (Appendix B Drawing 1). The height of fill over existing Areas 1 through 4 is constrained by the materials used in the construction of the LCRS of those areas. Unless otherwise approved, the final grades will be constructed with slopes averaging no steeper than 3:1 (horizontal: vertical) to reduce erosion and for slope stability. The slopes will be constructed with 15-foot minimum width benches to limit landfill slope lengths and to provide for surface runoff without promoting excessive erosion. Surfaces will be provided with a minimum 3 percent slope to provide sufficient slope for storm water runoff after refuse consolidation and settlement. The cover will be designed to meet Title 27 prescriptive standards or an approved engineered alternative. The County contemplates using an evapo-transporative (ET) closure cover as an engineered alternative based on experience at the Foothill Sanitary Landfill, where the ET cover was demonstrated to be twice as effective as an intact prescriptive closure cap. The final design will include a system of surface drainage facilities to control storm water run-on and runoff during construction and operation, and after completion of the landfill. These facilities will consist of ditches, culverts, down-coming drains and benches. The design will address erosion issues by limiting water velocities and using erosion control structures (down drains, etc.) where necessary. Both the initial construction and final cover and any later repair work that involves the cover low- hydraulic-conductivity layer (if present) will be completed in accordance with an approved construction quality assurance plan.