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One soil sample was collected from boring B11, located near the sandblasting area. Laboratory <br /> analysis did not detect concentrations of heavy metals that exceeded the USEPA Region 9 PRGs <br /> for direct contact exposure pathway for industrial soil. <br /> Thirty soil samples were collected from 10 borings along the north boundary drainage ditch. <br /> Laboratory analysis detected 20 mg/kg of oil-range hydrocarbons in one near-surface sample <br /> (Boring DD6 at 0.5 foot bgs). Laboratory analysis did not detect concentrations of extractable <br /> hydrocarbons in any of the other 29 samples. Metals concentrations detected in the samples <br /> were all below applicable regulatory guidelines (Table 3). No evidence was found to confirm the <br /> presence of petroleum hydrocarbons, lead, and zinc detected in previous surface samples. The <br /> likelihood of extensive lateral or vertical impacts from the previously detected contamination is <br /> considered very low. No further investigation is recommended for the north boundary drainage <br /> ditch. <br /> The bluish white crystalline powder identified beneath the pavement upwelling areas was <br /> determined to contain high copper concentrations and was tentatively identified as copper <br /> sulfate. The powder reportedly has no hazardous properties, but is toxic if ingested. The extent <br /> of the buried chemical was not determined, but is not expected to extend beyond the upwelling <br /> areas. Versar recommends removal of an estimated 100 cubic yards of soil for disposal at a Class <br /> I landfill. <br /> 4.3 OMS <br /> Areas of concern at the OMS comprise the former vehicle fueling station in the parking lot <br /> between the OMS and CSMS, and the vehicle wash rack south of the OMS building. Elevated <br /> concentrations of petroleum hydrocarbons were detected at depths of 10 to 25 feet bgs in March <br /> 2002. <br /> Three soil borings (1330 through B32)were advanced adjacent to the former location of a 10,000- <br /> gallon diesel UST and 5,000-gallon gasoline UST associated with the former vehicle fueling <br /> station southeast of the OMS. Previous investigations had determined that petroleum <br /> hydrocarbons identified in shallow soils (from 10 feet to 25 feet bgs) may have the potential to <br /> impact groundwater. The findings of the 2004 investigation identified petroleum hydrocarbons <br /> in deeper soils (from 35 to 45 feet bgs) and in groundwater. The lateral extent of groundwater <br /> impact was not determined to the north, east, or south. The lateral extent of groundwater impact <br /> was tentatively defined to the west by soil borings B33 and B34. Further investigation is <br /> recommended to determine the lateral extent of petroleum hydrocarbons in groundwater. <br /> Two soil borings (1333 and B34) were advanced adjacent to the vehicle inspection rack located <br /> south of the OMS building to further define the extent of petroleum hydrocarbons detected at 10 <br /> feet bgs in previous investigations. Evidence of extensive impacts from the previously detected <br /> petroleum hydrocarbon contamination was not encountered. Evidence of groundwater impact <br /> was not detected. No further investigation is recommended for the Vehicle Inspection Rack. <br /> 104700.4766.230/085EPT2004 12 <br />