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REG 603 UPDATE-6 2/21/92 <br /> 1 . 0 INTRODUCTION <br /> This update, STATUS UPDATE #6, represents data collected at the <br /> site for quarterly ground water sampling and remediation <br /> documentation during the months of July, 1991 through January, <br /> 1992. During this time a thermal oxidation unit has been <br /> installed and vapor extraction for soil and ground water <br /> remediation has been started. Also addressed in this report are <br /> the comments presented in a letter review of this site from San <br /> Joaquin County Health, dated December 5, 1991 . <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; MDB&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 #5 , January - June, <br /> 1991) . <br /> The following are the conclusions and recommendations of the <br /> UPDATE STATUS REPORT #5: <br /> CONCLUSIONS <br /> 1 . Ground water beneath the site is conatminated with <br /> dissolved gasoline range hydrocarbons, with a sheen of <br /> floating product found at monitor wells MW1, MW3 and <br /> MW10 . <br /> 2 . Soil contaminated with gasoline range hydrocarbons <br /> exists beneath the tank field from the 25 foot depth to <br /> top of ground water. <br /> 3 . A vapor extraction source test indicates that a vapor <br /> stream consisting of approximately 37, 867 ppm gasoline <br /> range and 14% methane will be produced from the <br /> formation. <br /> 4. Ground water gradient is presently to the north and east <br /> and indicates a discharge cycle (June 27, 1991) after <br /> the recent rains in the area during the months of April <br /> and May, 1991. <br /> PAGE 1 <br />