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County Response: The County proposes the following schedule: • Installation of four (4) LFG extraction wells and associated piping by June 30, 2015 • Startup and monitoring of the 4 new LFG extraction wells within five (5) days following completion of installation of wells and piping tie-ins to the existing system • Conducting a field ROI investigation of the existing wellfield within 90 days of approval of the revised EFS • Installation of five (5) triple -probe vadose zone soil gas wells by June 30, 2015 • Complete delineation of LFG plume in the vadose zone — dependent upon results of monitoring new tri -level wells anticipated to be completed by August 30, 2015. Although, the design and schedule of Phase 2 will be impacted by the monitoring results acquired during Phase 1, Phase 2 wells if necessary will be installed by June 30, 2016. This installation will also require approval from San Joaquin County Environmental Health Department and perhaps other agencies. However, the County believes the required permitting by these agencies can be obtained to meet this schedule. Water Board Question: What is the condition of the existing wells? County Response: The wellfield was inspected by SCS Field Services in March 2013, under contract to Ameresco, the third party LFGTE operator. This inspection indicated that of the nine (9) existing wells, only one (Dwell, GX-09, potentially has a partially damaged casing. All nine (9) wells were sounded to check their depth in 2013 versus their as -built depth in 2007. The sounding results for well GX-09 indicate that SCS personnel were only able to reach a depth of 49 feet below the top of the well's vertical casing, which suggests that there may be a partial pinch or other damage at that depth prohibiting the sounder from reaching the well's installed depth of 75 feet. It is also possible that unless this well was lowered to account for settlement, Regardless, based on recent monitoring data however, the well appears to continue to function normally. In addition, there was no significant water found within the well casings to cause concern. Water Board Question: What is the system capacity for the gas to energy plant? What is the historical daily average flow into the plant? County Response: The LFGTE power plant has a design capacity of approximately 1,500 standard cubic feet per minute (scfm) of LFG depending on LFG quality. Typically, the LFGTE power plant utilizes all the LFG collected by the LFG collection system, approximately 1,200 scfm of LFG daily on average. Foothill Sanitary Landfill 10 Department of Public Works, Solid Waste Division Revised Engineering Feasibility Study County of San Joaquin — December 19, 2014