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REG 603 UPDATE-8 7/17/92 <br /> 1.0 INTRODUCTION <br /> This update, STATUS UPDATE #8, represents data collected at the <br /> site for quarterly ground water sampling and remedzatton <br /> documentation during the months of April, May and June, 1992. <br /> During this time a thermal oxidation unit has been operating and <br /> vapor extraction for soil and ground water remediation is taking <br /> place Also represented in this report are quarterly ground water <br /> sampling results from samples obtained on June 8, 1992 <br /> 1 1 LOCATION <br /> The station is located at 6425 Pacific Avenue at the intersection <br /> of Douglas Road, in San Joaquin County, Stockton, California. The <br /> site lies in Section 21, T2N; R6E, MDS&M at approximately 12 feet <br /> above mean sea level (MSL) (see Figures 1, 2, and 3) The parcel <br /> is # 31 and can be located in Assessor's Book 97 on page 41 (97- <br /> 041-31) . <br /> 1.2 PREVIOUS REPORT (UPDATE STATUS REPORT #6, July, 1991 - <br /> . January, 1092) . <br /> The following are the conclusions and recommendations of the <br /> UPDATE STATUS REPORT #7: <br /> 4.0 DISCUSSION AND CONCLUSIONS <br /> As stated in earlier reports, the soil is contaminated -with <br /> gasoline range hydrocarbons beneath the tank field (MW10) and <br /> along the capillary fringe of the ground water, MW1, MW2, MW3 and <br /> MW10 Ground water beneath the site contains the dissolved <br /> constituents of gasoline range hydrocarbons and has spread out <br /> from beneath the site to the north MW-6, to the south MW-7 to the <br /> west MW-9 and to the east MW-8. <br /> Vapor extraction commenced on October 17, 1991 and up until March <br /> 18, 1992 has operated for 2611 hours out of a possible 3674 for a <br /> 71% run time, destroying 16, 156 pounds of gasoline range <br /> hydrocarbons_ Si-ce the !act statwo report, February 3, 1992, a <br /> total of 4884 pounds of gasoline range hydrocarbons have been <br /> removed/destroyed. DCE, TCE and PCE screening indicates that <br /> these compounds are not present in the vapor stream at this site <br /> Ground water elevation measurements show the ground water is being <br /> mounded at the lower K value wells MW3 and MW10, while the overall j <br /> flow direction is to the northeast and southeast <br /> . Ground water sample results obtained on December 17, 1991, <br /> PAGE 1 <br />