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. Former Beacon Station 494 <br /> Stockton, Calxforma October 8, 1996 <br /> Appendix B Closure Report <br /> the northern and southeastern edge of the former UST cavity, south of VW-1, and an angle <br /> boring originating north of the dispenser islands and terminating between the dispensers at <br /> approximately 50 feet vertical bsg Benzene in all samples analyzed from these bonngs was <br /> below the laboratory detection limits, and TPHg was reported above 100 mg/Kg in the <br /> samples collected from 40 and 45 feet bsg in CB-2 Laboratory results are compiled in <br /> Table 1, August 8, 1995 Assessment Report (Appendix B) Using these data an <br /> Isoconcentration map depicting the final TPHg distribution in soil (Figure 5) was created <br /> and included with this report It appears that the VES has been successful in removing the <br /> gasoline-range hydrocarbons from the soil <br /> Current Distribution of Petroleum Constituents in Groundwater <br /> Groundwater samples collected on May 30, 1996 were submitted for Iaboratory analyses of <br /> . TPHg, BTEX, and MTBE Because the depth to groundwater had risen above the tops of the <br /> monitoring well screened interval, a pump was utilized that could effectively drawdown the <br /> water level below the screened intervals prior to sampling and thereby assure a <br /> representative sample of groundwater The sampling results along with the previous results <br /> from Horizon and AMV groundwater monitoring are included within Appendix C During <br /> the May 30, 1996 sampling, benzene was reported in MW-3 at a concentration of 12 ug/L <br /> and below the laboratory detection Iimit of 0 50 ug/L in the other monitoring wells MTBE <br /> was below the laboratory detection limit (5 0 ug/L) in all monitoring well samples The <br /> current distribution of benzene in groundwater is depicted on the Benzene Isoconcentration <br /> Map (Figure 6) <br /> 1494 APB 9 HORIZON ENVIRONMENTAL INC <br />