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' the report of this work was completed, a Work Plan for an additional subsurface investigation <br /> ' was submitted to PHS/EHD (USTEC, August 1990) <br /> 3.1.1 Soil Stockpile <br /> ' Two samples were collected from the tank excavation soil stockpile, and analyzed for- heavy <br /> metals, industrial solvents (by EPA Method 381018015), hazardous waste characteristics of <br /> ' reactivity, pH, flashpoint, and hazardous waste bioassays using flathead minnows <br /> ' The 17 industrial solvents tested were all nondetectable Flashpoint was nonhazardous and <br /> was greater than 100 OC (212 OF) The pH was normal at 8 2 and 8 7 The fish bioassays <br /> indicated the soil was nonhazardous, and had an LC-50 (Lethal Concentration at 50% kill) of <br /> greater than 1,000 ppm The heavy metals detected were arsenic, barium, chromium III, <br /> cobalt, copper, lead, mercury, nickel, vanadium, and zinc After review of normal soil <br /> ' background concentrations reported in the scientific literature (Lindsay, 1979, Scott, 1991) it <br /> was determined that the heavy metal concentrations detected were at or below normal <br /> background concentrations <br /> ' USTEC obtained a Permit for Uncontrolled Aeration from the San Joaquin Valley Unified Air <br /> Pollution Control Distnct (APCD) for aeration of the tank excavation soil stockpile, with the <br /> ' exception of the drums containing soil from the upper 20 feet from borings B-1, B-2, and B-5 <br /> (USTEC, November 1990) This upper 20 feet of soil was transported to Ogden <br /> Environmental Services in Stockton, California where it was incinerated <br /> 1 <br /> 3.2 Assessment of Soil Contamination <br /> ' 3.2.1 Soil Gas Survey <br /> In May 1990, a soil gas survey was conducted by USTEC to assist in determining the locations <br /> ' of proposed groundwater monitoring wells and soil borings (USTEC, October 1990) Twenty- <br /> eight soil probe vapor points were sampled for concentrations of petroleum hydrocarbons <br /> ' Soil gas TPHg concentrations ranged from nondetectable to 90 ppm, weight to volume The <br /> majority of vapors appeared to be located immediately south of the former gasoline UST <br /> 1 <br /> n 10540061reports\CLO1195 doe 3 <br /> • <br /> 1 <br /> SMTN <br />