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• shop building. Other COCs potentially related to activities in these two areas were not detected <br /> in soil or soil gas. Oil-weight petroleum hydrocarbons was detected at a concentration of 234 <br /> mg/kg at a depth of 10 feet bgs at the location of the former hazardous materials storage east of <br /> the carpenter shop, and 123 mg/kg at a depth of five feet bgs adjacent to the carpenter shop <br /> location. Based on these relatively low concentrations of oil, and the absence of other CDCs in <br /> soil and soil gas at these locations, Versar does not believe further investigation is warranted in <br /> this area. <br /> Oil-weight petroleum hydrocarbons, zinc, and lead were detected in composited soil samples <br /> collected at the surface and at a depth of five feet bgs along the ditch providing surface drainage <br /> from vehicle storage areas east of the CSMS and Armory buildings. The soil samples were <br /> composited for this investigation to screen the drainage ditch for the presence of COCs. The <br /> concentrations of oil-weight petroleum hydrocarbons and metals were found to be primarily <br /> present in the surface soil, and are sufficiently elevated to warrant further investigation. Versar <br /> recommends collecting discreet soil samples at randomly selected locations along the length of <br /> the drainage ditch to assess actual concentrations of petroleum hydrocarbons and zinc. <br /> 6.3 OMS <br /> Jet fuel-weight petroleum hydrocarbons were detected in soil at a depth of 10 feet bgs at a <br /> concentration of 10,500 mg/kg, with heavier, oil-weight petroleum hydrocarbons present at the <br /> • same depth at a concentration of 153 mg/kg. The source of the two petroleum hydrocarbons is <br /> likely related to operations of the vehicle inspection rack; VOCs were not detected in soil gas in <br /> this boring. Based on the depth and concentrations of the petroleum hydrocarbons, Versar <br /> recommends further assessment of the vertical and lateral distribution of petroleum hydrocarbons <br /> in this area. SVOCs, and metals associated with used engine oil should be included in the <br /> assessment. <br /> Gasoline and diesel-weight petroleum hydrocarbons were detected in soil samples collected at a <br /> depth of 25 feet bgs at concentrations 25.4 mg/kg TPH-g and 209 mg/kg TPH-d. Versar <br /> recommends further assessment of the vertical and lateral distribution of petroleum hydrocarbons <br /> in this area. <br /> 7.0 REFERENCES <br /> Canonie Environmental. Laboratory Report(for OMS #24 2,000 gallon sump removal)for Mr. <br /> Hassan Pejuhesh, Office of the State Architect. August 18, 1987 <br /> California Army National Guard. 1985 to 1993. Various Environmental Safety and Industrial <br /> Hygiene Surveys of the OSM#24, Stockton. <br /> • 2187-01/3134-100/MAY26'00 17 <br />