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in MW -5 and MW -8 and carbonate in MW -4 indicate the prime cause of <br />contamination to be LFG. The new LFG wells will be installed to collect LFG and <br />will provide better extraction of LFG, thus reducing the VOC impact on the ground <br />water. The Regional Water Quality Control Board has approved the installation of <br />the new LFG wells as corrective action to mitigate the impact to ground water. <br />The contractor will be required to comply with this work plan and construct new <br />LFG wells per the construction drawings and specifications. <br />2.1 WELL LOCATION <br />Three LFG wells EW -40, EW -41, EW -42 will be installed near the northern <br />property boundary of CHSL (Figure 2). Two wells EW -43 and EW -44 will be <br />installed within the footprint of the landfill. <br />2.2 DRILLING <br />Solid Waste Division (SWD) will obtain drilling permits from San Joaquin County <br />Environmental Health Department (EHD). The wells will be drilled by a licensed <br />contractor. A boring log will be compiled during drilling by the contractor using a <br />form provided by SWD (Appendix A). <br />Wells EW -40, EW -41, EW -42 will be drilled into the refuse outside the existing <br />closure cap to the depths specified in the well schedule (Figure 5). Wells EW -43; <br />EW -44 will be drilled inside the footprint of the landfill. Depths of all wells will be <br />above seasonal ground water table. Drilling of the wells will include excavation of <br />refuse and minor contact with refuse. Excavated refuse and soil with refuse and <br />construction debris will be placed in a bin and disposed off-site. <br />A. Abondoned Borings <br />Abondoned borings will be backfilled with clean soil, compacted in two -foot lifts, up <br />to four feet below grade. A bentonite seal, four inches thick, will be placed in the <br />borehole four feet from the surface. The borehole will then be capped with <br />compacted clean soil. <br />2.3 WELL CONSTRUCTION <br />It is anticipated all wells will be constructed immediately after drilling. <br />A. Well Laterals <br />The new LFG wells will be connected to the existing landfill gas system with a 4" <br />Work Plan — LFG Extraction Well Installation San Joaquin County <br />Corral Hollow Sanitary Landfill Public Works Department <br />Solid Waste Division <br />