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------------------- <br /> Extended Site Characterization Report: 7500 West Eleventh Street, Tracy, CA. Page 30 <br /> xylene isomers at 370 gg/L, 11 gg/L, and 3.6 gg/L, respectively. There were no <br /> '.� detectable concentrations of toluene. <br /> Further to the north, and down-gradient from the former locations of the underground <br /> tanks, no detectable concentrations of analytes of concern were detected in samples <br /> recovered from Monitoring Wells ATCMW-4 and ATCME-5. Historically, MTBE, at <br /> ` concentrations up to 31 gg/L, had been detected in samples of groundwater recovered <br /> from Monitoring Well ATCMW-2 at this site, but none was detected in any of the <br /> groundwater samples recovered on June 14, 2001. Although that site remains under the <br /> i oversight of the SJCEHD, given its distance from the plume of affected groundwater <br /> emanating from the site at 7500 West Eleventh Street, its essentially co-gradient location <br /> to that site, and the limited area over which the groundwater has been found to be <br /> affected by analytes of concern, it is SJC's opinion that fuel hydrocarbons released there <br /> have not commingled with those released at the 7500 West EIeventh Street site. <br /> 7.2.4 7474 West EIeventh Street <br /> On June 2, 1988, two underground fuel tanks were removed from the property at 7474 <br /> :-, West Eleventh Street at the locations shown on Figure 12. That site, previously owned by <br /> C&B Equipment, is now the site of Troy's Body and Paint. Following removal of the <br /> .:' tanks, concentrations of gasoline at 2,880 mg/Kg, with benzene, toluene, ethyl benzene <br /> and total xylene isomers at 9.73 mg/Kg, 6.41 mg/Kg, 42.4 mg/Kg and 79.5 mg/Kg, <br /> respectively, were found in soil at a depth of 5.5 to 6 ft BGS near the former location of <br /> the tanks. A trace of MTBE, at a concentration of 5.2 gg/L, was detected in groundwater <br /> recovered from a groundwater-quality monitoring well (Well TGIMW-1 - see Figure 12 <br /> installed a short distance down gradient from the former location of the tanks, but was not <br /> subsequently detected in groundwater samples recovered from that well or any of the <br /> others installed at the site. <br /> Results of a round of groundwater-quality sampling and analysis performed on March, <br /> - 18, 1998 indicated the presence of 909.0 gg/L of TPH(g), with benzene, toluene, ethyl <br /> ___ benzene and total xylene isomers at 3.0 gg/L, 3.0 gg/L, 12.0 gg/L and 39.0 gg/L, <br /> -:. respectively, in groundwater recovered from Well TGIMW-101 located close to the <br /> former tank pits, but there were no detectable analytes of concern in samples recovered <br /> from Well TGIMW-4, the most westerly well on that site and the closest to the property <br /> at 7500 West Eleventh Street. Nor were there any detectable analytes of concern in the <br /> sample from Well TGIMW-5, the well installed at the greatest distance down the <br /> hydrogeologic gradient from the former tank pits on the 7474 West Eleventh Street <br /> property. <br /> F. The SJCEHD and the RWQCB closed the case file for 7474 West Eleventh Street site on <br /> November 21, 2000. The area of the subsurface affected by the release of gasoline at the <br /> 7474 West EIeventh Street site is hydrogeologically co-gradient to the locations on the <br /> 7500 West Eleventh Street property where fuel hydrocarbons were released and, as <br /> indicated by the data presented above, is of limited lateral extent. In SJC's opinion, fuel <br /> lost to the subsurface at 7474 West Eleventh Street has not commingled with the plume <br /> sic <br />