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R603 UPDATE-11 11/19/92 <br /> 1 .0 INTRODUCTION <br /> This update, STATUS UPDATE #11, represents data collected at the <br /> site for the month of October, 1992 ( from October 16 , thru <br /> November 17, 1992 ) . During this time, a thermal oxidation unit <br /> has been operating and vapor extraction for sail and ground water <br /> remediation is taking place. <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, 3 ) . The parcel is # <br /> 31 and can be located in Assessor' s Book 97 on page 41 ( 97-041- <br /> 31 ) . On October 2 , 1992 , a licenced surveyor with Nolte & Assoc. <br /> 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 . <br /> 1 . 2 PREVIOUS REPORT (UPDATE STATUS REPORT #1 O, SEPTEMBER - <br /> OCTOBER, 1992 UPDATE STATUS REPORT) . <br /> The following are the conclusions and recommendations of the <br /> UPDATE STATUS REPORT #10: <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 ) , see Figure 6 . Ground water beneath the site contains the <br /> dissolved constituents of gasoline range hydrocarbons and has <br /> spread out from beneath the site to zhe north (14W-6 ) , to the south <br /> (MW-7 ) to the west (MW-9 ) and to the east (MW-8 ) . The latest <br /> ground water sampling, September 22, 1992 , has shown a decline in <br /> the lateral extent of the plume, see Figure 5A ( 12-17-91 ) and <br /> Figure 5B ( 9-22-92) . <br /> Vapor extraction commenced on October 17 , 1991 and up until <br /> October 16, 1992 has operated for 4864 hours out of a possible <br /> 8063 . 25 for a 60% run time, destroying 35 , 132 pounds of gasoline <br /> range hydrocarbons. Since the last status report, September 3 , <br /> f 7 78 ounds of gasoline ranee h drocarbons have <br /> 1 J9L � I.i totall VY -J pv g y hydrocarbons�/ <br /> been removed/destroyed in 662 . 5 hours of operation ( 11 . 44 pounds <br /> per hour or 274 . 52 pounds per day of operation) . DCE, TCE and PCE <br /> . screening indicates that these compounds are not present in the <br /> vapor stream at this site . <br /> PAGE 1 <br />