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• TABLE I• Analytical results of soil samples from UST excavation and stockpile Sample Date TPH-D Benzene Ethylbenzene Toluene Xylenes Identification Sampled (mg/kg) (mg/kg) (mg/kg) (mg/kg) (mg/kg) T1-NW-10'4" 3/20198 < < < < < T1-SE-10'4"#2 3/20198 < < < < < D1-4' 3/20/98 < < < < < SP1-S 3/20/98 220 < < < < SPI-N 3/20/98 35 < < < < Method Detection 0 5 0 005 0 005 0 005 0 010 Limit Notes mg/kg=milligrams per kilogram TPH-D=Total Petroleum Hydrocarbons as Diesel TABLE 2 Analytical results of groundwater samples from UST excavation Sample Date TPH-D Benzene Ethylbenzene Toluene Xylenes Identification Sampled (mg/L) (µg/L) (µg/L) (µg/L) 41g/L) Excavation 3/18/98 53 <2 5 <2 5 <2 5 <5 0 Pit Water 3/20/98 41 <0 005 2 2 27 Notes . mg/L=milligrams per Liter µg/L=micrograms per Liter TPH-D=Total Petroleum Hydrocarbons as Diesel The SJCo PHS/EHD filed an "Underground Storage Tank Unauthorized Release (Leak)/Contaminated Site Report" and ordered an investigation to determine the extent of soil and groundwater contamination A total of 136 6 tons of petroleum hydrocarbon-contaminated soil was transported from the site for treatment and disposal at the Forward, Incorporated Class Il certified landfill in Manteca CAL INC submitted an "Underground Storage Tank Closure Report" to ABF Freight System, Inc in May 1998 On August 20, 1998, CAL INC installed three groundwater monitoring wells at the site in order to determine whether the soil and groundwater had been impacted by the storage of diesel fuel in the UST The SJCo PHS/EHD approved the site characterization work plan by CAL INC on August 11, 1998 Monitoring well MW-1 was installed at the* site of the former UST The other wells, MW-2 and MW-3, were install about 40 feet down the inferred hydraulic gradient from the UST(Figure 2) The wells are 25 feet deep and constructed of 2-inch diameter PVC plastic with 0 010-inch slotted well screens between depths of 5 and 25 feet below surface grade (see attached well logs) The results of the investigation were submitted by CAL INC to ABF Freight System, Inc in a report titled "Site Characterization Report, ABF Freight System, In , 2427 West Yosemite Avenue, Manteca, California" and dated November 1998 These are summarized below The borings intersected medium-grained sands with a layer of silty clay between depths of 20 and 22 feet below grade Soil samples were collected in 6-inch long brass sample tubes lining a split-spoon sampler generally at 5-foot intervals down the borehole A total of 14 soil samples from the three boreholes were analyzed for TPH-D and BETX On August 24, groundwater samples were collected from the three wells . with disposable polyethylene bailers with volatile organic compound sample ports, after purging at least three well casing volumes These samples were analyzed for TPH-0, TPH-G, BETX, methyl tert-butyl