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LFG Evaluation Memo , December 4, 2013 Page 4 of 9 ' Results of the CO testing, indicated a range of 0 to 74 ppmv. These CO results are considered to be normal background readings for waste decomposition gases. Based on observed normal range ' extraction well operating temperatures and normal background CO concentration test results there is no indication of subsurface oxidation occurring within the landfill site. However, SCS does recommend that operational goals be re-evaluated to decrease the levels of oxygen within the waste ' mass to reduce the potential for future oxidation. Finally, SCS performed Hydrogen Sulfide (H2S)testing at each individual LFG extraction well to , verify that the wellfield and flare can be monitored safely in accordance with OSHA and SCS requirements. The maximum H2S reading observed at was 2.0 ppmv which is well below the 100 ppmv threshold for additional health and safety controls to be implemented. ' LFG EXTRACTION SYSTEM INSPECTION AND MAPPING During the inspection, all above-grade wellhead components, valves, flex hoses, fittings and sample , ports were inspected for proper operation. During this monitoring, SCS utilized a global positioning system (GPS) capable Landtec GEM-5000 instrument to create a site map with the monitoring data which is also stored in the SCS Data Services®and Management System. A PDF copy of the map has been provided in Attachment B, and an interactive version, which will show the monitoring results, obtained along with GPS data is available to the County through the SCS Data , Services®and Management System. With the exception of the blower/flare station and extraction well risers, all LFG extraction system , components including extraction header and lateral piping, isolation valves,well control valves and condensate traps are installed below grade. Therefore our observations were limited to the piping, valves and instrumentation in the blower/flare station, and accessible condensate system , components. Results of the visual inspection of the above ground accessible components indicated that most of the current LFG extraction system control valves, hoses and associated lateral pipelines are in good condition. We saw no evidence of conditions that would compromise overall LFG collection system integrity. However SCS observed some locations that are in need of minor maintenance ' described below as follows: • Accumulated debris was observed within several extraction well monitoring vaults which ' inhibit proper monitoring and inspection and we recommend the material be removed as needed(see attached photos). • Several LFG extraction well test ports are age deteriorated and in need of replacement,to r restore proper monitoring capabilities (see attached photos). LFG CONVEYANCE PIPELINE MONITORING AND VISUAL , INSPECTION SCS performed a visual inspection of all above-ground LFG components to determine if any ' upgrades or maintenance was required. Any surging in pressure, low points in the pipeline with accumulated liquids (condensate)or any other components requiring maintenance are also described below.