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Case Closure Report Former Tosco(Unocal) SS No 5421, Stockton,California July 8, 1998 and UX-2-25 were collected at depths of 22 and 25 feet bgs, respectively Each soil sample was analyzed for TPH as gasoline, BTEX, and MtBE and oxygenate compounds These samples contained 16 and 15 ppm TPHg, 0 32 and 0 41 ppm benzene, respectively MTBE was not detected in either sample On April 21, 1998, the northern center of the pit was over-excavated and samples UX-7-26 and UX-8-26 were collected from the bottom at a depth of 26 feet bgs The samples contained 10 and 24 ppm TPH as gasoline, and 0 068 and 0 77 ppm benzene, respectively. MTBE was not detected in either sample Oxygenate compounds were not detected in any of the over-excavation samples. In total, an area approximately 26 feet north-south by 20 feet east-west by 8 to 12 feet deep was over- excavated from the bottom of the UST complex excavation (approximately 250 cubic yards) Upon removal of the waste oil UST on April 15, 1998, one soil sample was collected from beneath the center of the UST at a depth of approximately 11 feet bgs The soil sample was analyzed for TPH as gasoline, BTEX, MTBE, oxygenate compounds, TPH as diesel, Oil and Grease (O&G), volatile organic compounds (VOCs), semi-volatile compounds (SVOCs), and ICRP 5 metals No petroleum hydrocarbons were detected in the sample Four soil samples were collected in native material immediately beneath the four dispenser locations at a depth of 4 to 6 feet bgs on April 15, 1998 Each soil sample was analyzed for TPH as gasoline, BTEX, and MtBE and oxygenate compounds Petroleum hydrocarbon • concentrations ranged from not detected to 19 ppm TPH as gasoline, not detected to 0 82 ppm benzene and not detected to 0 089 ppm MtBE All samples were reported as not detected for oxygenate compounds Two soil samples were collected in native material immediately beneath the former hydraulic lifts at a depth of 8 feet bgs on April 21, 1998 Each soil sample was analyzed for Total Petroleum hydrocarbons calculated as hydraulic fluid (TPH as hydraulic fluid) and reported as not detected One soil sample was collected in native material immediately beneath the former sand/water separator at a depth of 4 feet bgs on April 21, 1998 The soil sample was analyzed for TPHg, BTEX, MTBE, oxygenate compounds, TPH as diesel, O&G, VOCs, SVOCs, and ICRP 5 metals The sample was reported as not detected for petroleum hydrocarbons except for 0 016 ppm toluene and 0 023 ppm xylenes Soil removed from the UST complex excavation and over-excavation, waste oil UST excavation, product piping trenches, hydraulic lift excavations and sand/water separator excavation were stockpiled at the site pending disposal profiling and approval from the SJCPHS A total of 630 yards of stockpiled soil was transported from the site by Den Beste Transportation, Inc of Windsor, California to the Forward Inc Landfill in Stockton, California for disposal on May 19, 1998 Upon completion of excavation activities, clean imported fill material was used to backfill the excavations to the original grade The material was placed to lifts and mechamcally compacted to Tosco specifications 140162 03 9