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<br />Preliminary Closure and Postclosure Maintenance Plan 2-7 Department of Public Works/Solid Waste <br />North County Recycling Center and Sanitary Landfill County of San Joaquin <br /> <br />slope stability cross-sections for Areas 4 through 11 also showed adequate static factors of safety. <br />The results for the static slope stability of the most critical interim waste slope within Areas 5 through 11 yielded an acceptable static factor of safety if each future liner system design and construction satisfies specified shear strength values (Appendix C). <br />The results of the slope stability analysis indicate the existing and planned slopes meet the acceptance criteria of CCR Title 27. <br />2.5.6 Landfill Gas (LFG) Migration Monitoring <br />Title 27 CCR (20921) requires that owners or operators of all municipal solid waste landfill units implement routine LFG migration monitoring programs to ensure that concentrations of methane do not reach the lower explosive limit (LEL = 5% methane by volume in air) at the facility monitoring perimeter or exceed 25 percent of the LEL in facility structures. To comply with this regulation, the County has installed 18 monitoring wells at maximum 1,000-foot centers along a monitoring perimeter (Figure 3 and JTD Plate 6), and monitors on-site structures within the perimeter. These wells will continue to be monitored and maintained in the postclosure period per the Gas Monitoring and Control Plan (JTD Appendix I). On-site structures, if any, will also be monitored. <br />Analysis of samples from the perimeter migration monitoring network for VOC concentration may be required by regulatory agencies. <br />2.5.7 LFG Emission Control <br />LFG emissions will be controlled by an active LFG collection system. The first portion of this system was installed in 2006, and will be extended into the landfill as the landfill is developed such that little additional construction is anticipated at closure; however, a portion of the system will be reconstructed at closure. LFG condensate will continue to be delivered to the LCRS system and returned to the landfill with leachate in accordance with the current WDRs. Treatment of the collected gas may be by combustion in a flare (as it is today) or by utilization as fuel in a landfill-gas-to-energy facility. The closure cost estimate assumes combustion in a flare relocated to the south-west corner of the property sometime before closure. <br />Projected costs for operations and maintenance of an LFG collection and control system are included in the postclosure maintenance cost estimate. <br />2.5.8 Groundwater, Surface Water, NPDES, and Unsaturated Zone Monitoring <br />Groundwater Water quality is monitored consistent with the current WDRs (JTD Appendix A). The groundwater monitoring network presently consists of 13 groundwater monitoring wells (Figure 3 and JTD Plate14).