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R603 UPDATE-10 11/09/92 <br /> 1 .0 INTRODUCTION <br /> This update, STATUS UPDATE 110 , represents data collected at the <br /> site for the month of September, 1992 ( from September 3 , thru <br /> October 16, 1992 ) . During this time, a thermal oxidation unit has <br /> been operating and vapor extraction for soil and ground water <br /> remediation is taking place. Also presented in this report is the <br /> completion of the July 6 , 1992, offsite monitor well work plan. <br /> With the installation and sampling of monitoring wells MW11 and <br /> MW12 . - - <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, 3A and 3B) . The <br /> parcel is # 31 and can be located in Assessor' s Book 97 on page 41 <br /> ( 97-041-31 ) . On October 2 , 1992, a licenced surveyor with Nolte & <br /> Assoc . surveyed in all monitoring well locations, top of casing <br /> . elevations to a known datum, City of Stockton Bench Mark Number <br /> 12, elevation 11. 74 ' above mean sea level, see Appendix A. <br /> 1 . 2 PREVIOUS REPORT (UPDATE STATUS REPORT #9, JULY - AUGUST, 1992 <br /> UPDATE STATUS REPORT) . <br /> The following are the conclusions and recommendations of the <br /> UPDATE STATUS REPORT #9 : <br /> 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 <br /> the west (MW-9) and to the east (MW-8 ) . The latest ground water <br /> sampliag, March 10 and Julie 18 , 1992, llave shown a decline in the <br /> lateral extent of the plume, see Figure 5 ( 6-18-92 ) . <br /> Vapor extraction commenced on October 17 , 1991 and up until <br /> September 3, 1992 has operated for 4201. 5 hours out of a possible <br /> 7024 for a 60% run time, destroying 27, 554 pounds of gasoline <br /> range hydrocarbons. Since the last status report, June 22, 1992, <br /> a total of 3114 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 /> PAGE 1 <br />