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AN <br /> inoculation. On most occasions, the highest concentration was recorded in VW-6. After <br /> inoculation,concentrations fluctuated somewhat,rising on days when the vacuum blower was <br /> disconnected and decreasing to near zero when the blower operated. Overall, inoculated <br /> wells showed an increase in carbon dioxide concentrations. However, those wells receiving <br /> air did not show as great of an increase of carbon dioxide concentrations. injection of <br /> ambient air into the well system apparently forces carbon dioxide away from the wells and <br /> lowers the concentration at the well head. <br /> Summa Canisters <br /> Vapor samples were collected from VW-1, VW-4, VW-5, VW-6, VW-7, MW-1, MW-4, and <br /> MW-14 in Summa Canisters on February 14 and 28. These were transmitted to Air Toxics <br /> %in Folsom, and analyzed for oxygen and carbon dioxide. Oxygen concentrations were similar <br /> in all wells except MW-1, where concentrations are considerably lower. Carbon dioxide <br /> concentrations are much higher in MW-1 than in the other wells, and all laboratory <br /> measurements exceed the CO2 concentrations measured in the field. The results are shown <br /> in Table 4, and the laboratory reports are presented as Attachment D. <br /> Air samples from VW-1, VW-4, MW-14, and MW-4 were analyzed for total petroleum <br /> hydrocarbons in the gasoline range (TPH) and benzene, toluene, ethylbenzene, and xylenes <br /> (BTE&X). However, after the initial samples were collected, it was decided (by GeoAudit <br /> and the CVRWQCB) that MW-1 and not VW-4 should undergo the hydrocarbon analysis. <br /> The results of the hydrocarbon analysis are shown in Table 5; the laboratory reports are <br /> presented as Attachment E. <br /> For VW-1, the blower was on prior to the initial sampling on February 14 and was off <br /> during the February 28 sampling. For MW-4 and MW-14, the blower was on for the entire <br /> month. - <br /> Hydrocarbon concentrations were very Iow in all the wells monitored.During the February <br /> 14 sampling, MW-14 had the greatest concentration of TPH; VW-4 had the greatest <br /> concentration on February 28. In VW-1, concentrations of TPH, ethylbenzene and xylenes <br /> increased, while concentrations of benzene and toluene decreased. In MW-4 and MW-14, <br /> all concentrations of TPH and BTE&X decreased. MW-1 and VW-4 were only sampled <br /> once, so no comparison could be made during February. <br /> SOIL MONITORING <br /> Boring P1 was drilled on February 28, 1994 to collect soil samples for direct monitoring of <br /> bacterial activity and hydrocarbon degradation. This boring was located 5 feet northwest of <br /> vapor well VW-1, and was continuously cored from 10 to 40 feet, where it terminated within <br /> the clay bed that separates the upper and lower sand beds. Samples were collected for <br /> analysis intermittently throughout the boring. <br /> G-bSW A.& 3 <br /> GEWEKE <br />