COMPLIANCE INFO_JTD APPENDIX A -L 2024

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Preliminary Closure and Postclosure Maintenance Plan 2-6 Department of Public Works/Solid Waste North County Recycling Center and Sanitary Landfill County of San Joaquin Soils will be excavated as needed for landfill operations, in sequence from lined areas 5 through 11. In general, each area will be excavated to approximate base grade of the next lined area by removing soil for daily and intermediate soil cover soil. According to the soil use analysis performed for the vertical expansion of the landfill to 320 ft MSL, the NCRC&SL has a surplus of soil for this use (Table 1). The existing central access corridor will be extended south with ramps down to the base of each area for initial equipment and refuse vehicle access. After each lined area is developed and filled above original ground level, access roads will be extended up the interior slopes of the refuse fill to upper fill elevations. To facilitate construction, operation, and closure of the final landfill area, soils excavated from the lined areas will be stockpiled at a location that facilitates use during closure. At this time, the County contemplates this stockpile north of the permitted footprint and east of the landfill access road (Figure 3). Approximately 1 million cubic yards of soil will be required for cover soil the final closure project of the final lined area and. Based on landfill development with the currently approved base liner system and the allowance for a 4.5-foot-thick final ET soil cover, the proposed excavation plan provides sufficient soil for development at refuse-to-soil ratio of 5:1 (v/v). Lower refuse-to-soil ratios will cause the final height of the landfill to be reduced or be addressed by importing soil. 2.5.4 Erosion Control Based on the U.S. Department of Agriculture’s Revised Universal Soil Loss Equation, the potential for soil loss from well-vegetated final slopes can control soil loss to below the 2-tons- per-acre criterion established in the U.S. Environmental Protection Agency (EPA) Guideline Manual for Landfill Design Liner Systems and Final Cover (EPA, 1982) (Appendix B of this PC/PCMP). When final soil cover is placed over completed landfill areas, the proposed soil cover will include organic materials, track-walked straw mulch, and hydroseeding. After vegetation is established, these measures will control soil loss to within the 2-tons-per-acre criterion established for landfills (EPA, 1982). 2.5.5 Stability Analysis The proposed final configuration of the site is found to have factors of safety greater than 1.5 under present conditions and design, and is therefore stable. In fact, the seismic analyses showed that the potential for permanent displacement does not exist during the maximum probable earthquake event along the critical cross-sections analyzed for the landfill (Appendix C). Stability of existing Areas 1 and 3 were analyzed assuming conservative shear strength parameters based on testing of actual liner materials. The results of the most critical global