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<br /> Onsite and Offsite Assessment Report 2
<br /> j The Southland Corporation,2725 Country Club Boulevard,Stockton,California „_,._._.... November 30,1998
<br /> The soil samples were analyzed for benzene,toluene, ethylbenzene,total xylenes(BTEX), methyl tert-
<br /> butyl ether(MTBE),and total petroleum hydrocarbons-as-gasoline (TPH-G) by EPA methods
<br /> 8 02 018 01 5 modified and oxygenates tert butanol (TBA), MTBE,diisopropyl ether(DIPE), ethyl-tert-butyl
<br /> ether(ETBE),tert-amyl methyl ether(TAME) by EPA method 8260. Two soil samples were also i
<br /> analyzed for total lead by EPA method 6010. Maximum benzene and TPH-G concentrations of 63
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<br /> milligrams per kilogram (mg/kg)and 7,200 mg/kg, respectively were detected beneath the south end of
<br /> ` the central UST. The highest MTBE concentration (40 mglkg)was detected beneath the southern end
<br /> of the western UST.TAME was detected in one sample at 2 mglkg. TBA, DIPE, ETRE, and total lead
<br /> were not detected.
<br /> The former Southland tank pit was subsequently overexcavated to a depth of 14 feet below grade,
<br /> removing the majority of the soil hydrocarbon source. About 230 (total) cubic yards of soil from the
<br /> former tank pit were removed by Belshire Environmental,a licensed waste hauler,to TPS (Richmond,
<br /> California),a licensed soil recycling facility. About 280 cubic yards of clean soil (as verified by analytical
<br /> results) removed from the new tank pit area were used as backfill material in the former tank pit. The
<br /> remaining clean soil from the new tank pit(about 700 tons, or approximately 500 cubic yards)was
<br /> hauled by a licensed waste hauler to a licensed disposal facility as it was geophysically unsuitable for
<br /> recompaction purposes.
<br /> { One soil sample was collected on July 30, 1998, from the southwest corner of the base of Southland's
<br /> new tank pit area. Benzene and TPH-G levels were 0.092 mg/kg and 1.5 mg/kg, respectively. MTBE,
<br /> TBA, and methanol concentrations were 23 mg/kg, 98 mg/kg,.and 240 mg/kg, respectively:. I
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<br /> The groundwater samples from beneath Southland Is former underground storage tanks were analyzed
<br /> for BTEX, MTBE, and TPH-G by EPA methods 8020/8015 modified and the oxygenates TBA,MTBE,
<br /> DIPE, ETBE, and TAME by EPA method 8260. In addition, one sample was analyzed for total lead by
<br /> EPA method 6010.Maximum dissolved benzene,TPH-G, and MTBE concentrations were 5,000
<br /> micrograms per liter u /L 140 000 u /L and 68,000 u /L respectively. Concentrations of TBA and
<br /> 9 P ( g )� � 9 � g
<br /> TAME ranged up to 23,000 pg/L and 1,200 pg/L, respectively. Total lead concentrations ranged up to
<br /> 0.82 milligrams per liter(mg/L). DIPE and ETBE were not detected. The Highest levels of dissolved
<br /> constituents were observed beneath the western UST. ;
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<br /> One grab groundwater sample was also collected from the base of Southland's new underground
<br /> storage tank pit area on July 27, 1998. Benzene and TPH-G were detected at concentrations of 300
<br /> pg/L and 3,100 pg/L, respectively. MTBE was detected at a concentration of 27 ug/L. `
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<br /> Dewatering of Southland's new underground storage tank pit was required prior to setting of the new
<br /> tanks. A total of 30,900 gallons(approximately) of groundwater were pumped from the new tank pit
<br /> area prior to completion of construction. The groundwater was hauled by a licensed waste hauler to a
<br /> - licensed recycling facility. Three conductor casings are present in the center of the new UST pit,to
<br /> facilitate groundwater monitoring well installation if needed during subsequent site assessments. The
<br /> 14117sar.rpt
<br /> FLUOR DANIEL GTI j
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