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Corral Hollow LFG System Audit and Upgrade Report • Perform one (1) complete round of LFG extraction well field monitoring. SCS monitored the all LFG extraction wells for the following: methane, carbon dioxide, oxygen, balance , gas and VOCs concentrations. Temperature, wellhead pressure, system pressure, and flow were measured and recorded. During the well field monitoring event, all above grade wellhead components, valves, hoses, and fittings were inspected for proper ' operation, leaks/damage, and condition noted. • Perform a visual inspection of all above-grade gas extraction wellheads and BFS piping. ' • Perform flow rate and pressure verification monitoring at select locations of the GCCS conveyance piping(header) system, where possible. ' • Perform field testing and inspection of perimeter LFG monitoring wells. • Perform field testing and inspection of the gas handling portion of the Site's GCCS, ' including the condensate injection system. Details on monitoring and testing procedures, results and conclusions are provided in ' Appendix A (Operations Review). A summary of key findings is as follows: • During the interval monitored, we found no evidence of physical damage, blockage, or , other factors that would compromise overall system performance of the GCCS main header or lateral systems. This was verified via inspection of accessible above-grade ' components and gas flow and vacuum testing at various points on header systems. • CCTV findings concluded that perforated zones of the inspected extraction wells are not ' restricted due to possible elevated liquid levels, including in the newly-installed wells. • Methane concentrations measured at extraction points ranged from non-detect to 34.9% , v/v. Please note that 24 of the 51 extraction wells (47% of the wellfield) were found to have methane concentrations below 10% v/v. The average methane concentration for all 51 wells equates to 12.4% v/v (not considering individual flows for each well). This is ' indicative of a low LFG generation rate, which is to be expected at an older landfill site (see below). For comparison, during the initial stages of waste decomposition, as- generated LFG typically contains methane at concentrations between 40 to 50% v/v. ' This low methane content also reflects the County's efforts to both reduce impact to groundwater and control perimeter LFG migration. • During the interval monitored, the gas condensate handling and injection system appears ' to be properly functioning; no leaks or significant liquids accumulation were observed. • Both extraction wells (EW-48 and -49) placed in the 1.6 acres expanded closure area on ' the northern edge of the landfill appear to be properly functioning; we saw no evidence that these wells are watered in or that extraction capabilities are compromised. ' 8 December 2013