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Nov . 19. 2004 3:23PM0 <br /> No.9751 P. 26 <br /> _. — <br /> page 3 <br /> Mr.Robert McClellon <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 an from 5 feet to 4 feet bgs. The remainder <br /> nument was installed at the top of each <br /> of the annulus was filled with neat cement. A stove pipe/mo <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 I <br /> methane,oxygen, and carbon dioxide using a hand-held portable landfill gas monitor. Before collecting I <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 1S.9%, weva a actme a C�llya developing <br /> vel p6in a plan to adequately <br /> address this situation. if you.have any questions,please g <br /> Sincerely, <br /> URS Corporation Americas <br /> ..( y �ne <br /> eni r Civil Engineer <br /> sures: Table 1--Summary of Results <br /> Figure 1—Vicinity <br /> Figure 2--Site Location Map <br /> Boring Logs <br /> K:1Wprvcvi5L55321GMMP1R\0816W.doc <br />