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ENVIRONMENTAL INVESTIGATION REPORT Unocal Service Statin No 5886 2701 West March Lane Stockton California t Delta Project No D095-066 Page 15 ' On October 27, 1995, the three new 15,000 gallon USTs were installed Approximately 10,000 gallons of ground water entered the excavation between October 26, 1995, and the completion of the tank tplacement on October 30, 1995 This ground water was pumped Into a Baker tank and removed from the site by RUST on November 2, 1995, and transported to Unocal's facility in Rodeo, California for ' recycling A copy of RUST's transport/disposal information is presented in Appendix H A final ground water sample was collected on November 2, 1995, from the 10,000 gallons of ground water stored in the ' Baker tank prior to disposal by RUST ' 4 7 4 Soil Sample Analytical Results Each sample was submitted to Sequoia for analysis of TPH as gasoline, TPH as diesel, and BTEX using ' the previously described methods Reported concentrations of benzene, toluene, ethylbenzene, total xylenes, TPH as gasoline, and TPH as diesel were all below the laboratory's limits of detection in each soil sample collected, with the exception of two sidewall soil samples which reported TPH as diesel at 1 9 mg/kg and 2 0 mg/kg A tabulation of the soil sample analytical results collected during the tank ' removal activities are presented in Table 8, Tank Removal Soil Sample Analytical Results Copies of the laboratory analytical reports and chain-of-custody documentation are presented in Appendix C ' 4 7 5 Ground Water Grab Samole Analytical Results Ground water grab samples collected on October 25 and 26, 1995, were analyzed for TPH as gasoline, ' TPH as diesel, and BTEX using the previously described methods In addition, the ground water grab sample collected from the tank cavity on October 25, 1995, was analyzed for toxicity for disposal ' characterization The concentration of benzene in each sample was reported at 7 3 /ig/L and 0 75 µg/L, respectively Concentrations of toluene, ethylbenzene, total xylenes, TPH as gasoline, and TPH as diesel were also reported for each sample The results from the ground water grab sample collected on November 2, 1995, were below the laboratory's limits of detection for BTEX and TPH as gasoline, but ' did report TPH as diesel at 180 /g/L A summary of the ground water analytical results collected from the tank excavation are presented in Table 7 Copies of the laboratory analytical reports and chairs-of- custody documentation are presented in Appendix C ' RPT 160 SJS