ARCHIVED REPORTS XR0001333 - Laserfiche WebLink

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ZMA January 7, 1993 Working To Restore Nature ARCO Service Station 2168, Stockton, California analyzed for halogenated volatile organic compounds using EPA Methods 5030/601, and the sample from well MW-2 was analyzed for TOG using EPA Method 5520B These samples were analyzed at Columbia Analytical Services, Inc in San Jose, California (Hazardous Waste Testing Laboratory Certificate No 1426) The sample from well MW-3 was also submitted to Sequoia Analytical in Sacramento, California, for analysis of total and fecal coliform bacteria. The results of analyses are summarized in Tables i and 2 Copies of the laboratory analysis reports are in the Appendix Results of analyses of water samples indicated TPHg, BTEX, and 1,2-dichloroethane were `detected in ground-water samples from the three wells The highest concentrations of TPHg and benzene were detected in well MW-3 (77,000 to 15,000 ppb, respectively) TOG and 1,2,-dichloropropane were detected in well MW-2 Total and fecal coliform bacteria were not detected in well MW-3 WORK IN PROGRESS On July 14, 1992, RESNA performed a vapor-extraction test (VET) at the site to evaluate the feasibility of vapor extraction as a remediation alternative for the vadose zone soil A report on this test is forthcoming At ARCO's request, RESNA will conduct further work at the site during January 1993 The work will be conducted to evaluate whether gasoline hydrocarbons are present in soil beneath the dispenser islands, and to install ground-water monitoring wells to further delineate gasoline hydrocarbons in ground water beneath the site CONCLUSIONS AND RECOMMENDATIONS The ground-water flow direction was to the northeast during this monitoring event Dissolved gasoline hydrocarbons and 1,2-dichloroethane were detected in samples from the ` three wells. TOG and 1,2-dichloropropane were detected in well MW-2 Total and fecal coliform bacteria were not detected in well MW-3 On this basis, we recommend continued quarterly evaluation of ground water beneath the site to include analyzing water samples from all morutoring wells for halogenated volatile organics in addition to TPHg and BTEX We understand that Emcon will conduct the next quarterly monitoring event in November 1992 We recommend that a copy of this report be forwarded to Mr Michael Infurna, San Joaquin Public Health Services, 445 North San Joaquin, Stockton, California 95202 and Mr Jim Manghan, California Regional Water Quality Control Board, 3443 Routier Road, Suite A, „ Sacramento, California 95827-3098 102&-cu 31009-6 3 i