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URS <br /> Mr. Robert McClellon Page 3 <br /> Supervisor R.E.H.S. <br /> August 16, 2004 <br /> The screened interval for each probe was installed at a depth from 6 feet to 15 feet below ground surface <br /> (bgs). The gas-migration monitoring probes, VW-1, VW-2, VW-3, and VW-4, were installed within <br /> boreholes BH-1, BH-2, BH-3, and BH-4, respectively. The annulus between the probe casing and the <br /> boring wall from the bottom of the boring (15.5 feet bgs) to 5 feet bgs was filled with pea gravel filter <br /> pack material. One-foot of bentonite was placed in the annulus from 5 feet to 4 feet bgs. The remainder <br /> of the annulus was filled with neat cement. A stove pipe/monument was installed at the top of each <br /> probe. The construction details of the probes are provided in the probe's corresponding boring log. <br /> Since discolored soil or odorous soil was not encountered during our activities, the soil cuttings were <br /> placed on the ground surface of the site as specified in the approved work plan. <br /> Quarterly Monitoring Activities <br /> On July 9, 2004, the monitoring activities at the site were completed. Each probe was measured for <br /> methane, oxygen, and carbon dioxide using a hand-held portable landfill gas monitor. Before collecting <br /> these measurements, the top of each probe was fitted with a stainless steel valve assembly, as requested <br /> by Mr. Tasiopoulos. Mr. Tasiopoulos was present during the measurement activities. These <br /> measurements were recorded in a field book. <br /> RESULTS <br /> The methane concentrations in VW-1, VW-2, and VW-3 were 0%. The methane concentration in VW-4 <br /> was 18.9%. The oxygen concentration in the probes ranged from 0% to 17.9%. The carbon dioxide <br /> concentration in the probes ranged from 0.9 to 29%. The results for each probe are summarized in <br /> Table 1. <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> Since the methane concentration in VW-4 was 18.9%, we are actively developing a plan to adequately <br /> address this situation. If you have any questions,please give me a call at(916)679-2081. <br /> Sincerely, <br /> URS Corporation Americas <br /> jEnmine <br /> Civil Engineer <br /> res: Table 1 —Summary of Results <br /> Figure 1 —Vicinity <br /> Figure 2—Site Location Map <br /> Boring Logs <br /> K:\Wprocess\25532\GMMPIR\081604.doc <br />