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2 The County of San Joaquin intends to continue expansion of the landfill footprint with the addition of Modules within a 200 -foot setback from the current property boundaries. The California Regional Water Quality Control Board (CRWQCB) has requested that one up - gradient well and one down -gradient well be installed to evaluate potential impacts from future landfill operations. The County has proposed two well locations (MW -4 and MW -5) based on the historic west-southwest groundwater gradient direction and the anticipated future landfill expansion limits. The current surface elevations at the proposed locations are approximately 339 feet above MSL for MW -4 and 239 feet above MSL for MW -5. The depth to the groundwater bearing zone is anticipated to be approximately 290 feet bgs in MW -4 and 200 feet bgs in MW -5. Existing and proposed well locations are shown on Plate 9. 6.8. FINAL GRADING PLAN The proposed landfill configuration is shown on the final grading plan for the site (Appendix C, and the Preliminary Closure/Post-Closure Plan in Appendix I). The landfill configuration is controlled by the existing refuse fill, surrounding topography, drainage, stability requirements, aesthetics, visibility, and end-use considerations. Current limitations on landfill bottom elevation and maximum height are discussed in Section 6.2.2. In the future, the County may seek to raise the permitted height limit of the landfill. This will be subject to regulatory approval, satisfactory slope stability analysis and other relevant design issues. This has an impact on the Preliminary Closure/Post Closure Maintenance Plan which will be revised based on the final height. Present permitted height is 432 ft MSL. To facilitate closure of Module I, and to maximize use of the site, the County intends to seek an increase of the height limitation. Final grades will be constructed with slopes no steeper than 3:1 (horizontal: vertical) to reduce erosion, and steep enough to provide sufficient slope for stormwater runoff after refuse consolidation and settlement. The final landfill slopes will be constructed to provide adequate drainage and prevent ponding after settlement of wastes underlying the upper landfill slopes. Drainage swales will be constructed in some areas of landfill slopes to reduce the overland flow velocity and direct overland drainage to the swales thereby reducing erosion problems. The drainage swales will be Foothill Sanitary Landfill Page 37 of 62 Public Works/Solid Waste JTD County of San Joaquin — Revised 10/6/05