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90371-R COT-3 <br /> W,.Award-Clyde Consultants <br /> appended. Only sample E-1 contained hydrocarbons above the detection <br /> levels ; 55 mg/kg TPH. Based on the sample results and observations made <br /> during the excavation, it appeared that the majority of the contamination <br /> had been removed. <br /> On October 21, 1986, the gas dispensing pump was relocated to allow the <br /> removal of material from the southwest corner of the excavation. The <br /> standing water in the hole was pumped into an adjacent portable tank for <br /> temporary storage. No oil or sheen was apparent on the surface of the <br /> water prior to pumping. During the subsequent excavation, the <br /> contamination appeared to be increasing towards the west as the odor from <br /> the soils became significantly stronger. The excavation was extended as <br /> close to the adjacent tank as possible and right up to the loading dock <br /> driveway. A soil sample (E-4) was taken from the southwest corner at a <br /> depth of about 6.5 to 7.0 ft. Although the water table was situated at a <br /> depth of approximately 5.5 to 6.0 ft, the strongest odors came from <br /> material at the above-sampling depth. This was consistent throughout the <br /> contaminated area . A sample ( PW-1) was also taken of the water pumped from <br /> the excavation prior to soil removal . The soil sample was found to contain <br /> 920 mg/kg TPH, 23 mg/kg benzene and 7.8 mg/kg lead whereas the water sample <br /> contained 10 mg/L TPH and 1.0 mg/L benzene. Copies of the lab results are <br /> appended. <br /> Observations made during the second excavation effort and the associated <br /> sample analyses suggested that the primary source of contamination was the <br /> existing 5,000-gal tank and not the removed tank. Because no historical <br /> spills from the existing tank could be confirmed, it was assumed that the <br /> contamination was the result of an occasional overfilling. This is <br /> somewhat supported by the fact that the contamination appears to be present <br /> only around the fill pipe end of the tank. It also appeared that the <br /> spilled product had been there for some time, as much of the contamination <br /> was below the water table indicating that it had been present for at least <br /> one if not several seasonal water table fluctuations. It was apparent that <br />