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R603 UPDATE-14 3/25/93 1 . 0 INTRODUCTION This update, STATUS UPDATE #14 , represents data collected at the site from January 19, through February 18, 1993 . During this time, a thermal oxidation unit was operating and vapor extraction for soil and ground water remediation was taking place . Lawrence Tank Testing (LTT) was also performing the twice a week purging of selected wells for ground water removal and treatment . The permit to dump treated ground water to the sewer was received and presently we are batch dumping the treated water from the "ConVault" monthly This water is collected from the vapor recovery condensate dropouts and the twice weekly purging of monitor wells MW1, MW2, MW3 , MW8 and MW10 by Lawrence Tank Testing (LTT) pumping service . Once the ground water recovery - treatment system has been completed, pumping will occur from monitor wells MW1 and MW3 . 1 . 1 LOCATION The station is located at 6425 Pacific Avenue at the intersection of Douglas Road, in San Joaquin County, Stockton, California. The site lies in Section 21 , T2N; RGE; MDB&M at approximately 12 feet above mean sea level (MSL) (see Figures 1, 2, 3) . The parcel is # 31 and can be located in Assessor' s Book 97 on page 41 (97-041-31) On October 2 , 1992 , a licensed surveyor with Nolte & Assoc . surveyed all monitoring well locations and top of casing elevations to a known datum, City of Stockton Bench Mark Number 12 , elevation 11 . 74 ' above mean sea level 1 2 PREVIOUS REPORT (UPDATE STATUS REPORT #12, DECEMBER , 1992- JANUARY 1993 UPDATE STATUS REPORT The following are the conclusions and recommendations of the previously submitted UPDATE STATUS REPORT #12 . 4 . 0 DISCUSSION AND CONCLUSIONS As stated in earlier reports, the soil is contaminated with gasoline range hydrocarbons Deneath the tank field (MW10) and along the capillary fringe of the ground water, (MW1, MW2 , MW3 and MW10) , see Figure 6 Ground water beneath the site contains the dissolved constituents of gasoline range hydrocarbons and had spread to the north (MW-6) , to the south (MW-7) to the west (MW- 9) and to the eagr__ (MW-12) . The latest ground water sampling, mb Deceer 9 , 1992, shows the continual decline in the lateral extent of the plume, see Table 1 and Figures 5A and 5B . Vapor extraction started October 17, 1991 and has operated for 5388 hours (December 18 , 1992) out of a possible 8821 5 hours, 61% run time, destroying 48310 pounds of gasoline range hydrocarbons Since the last status report, November 17, 1992 , 8768 pounds of gasoline range hydrocarbons have been removed/destroyed and an estimated 6573 pounds of oxidized PAGE 1