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VVZI �N C <br /> The exploratory excavation was terminated at a depth of approximately 18 feet bgs where <br /> groundwater was encountered Four soil samples and one water grab sample were <br /> collected from the excavation The soil samples were collected from all four quadrants of <br /> the excavation by lowering the backhoe bucket to approximately 17 feet bgs and removing <br /> the petroleum hydrocarbon-contaminated soil from the sidewall of the excavation (McLaren, <br /> 1989a) <br /> The water grab sample was collected from groundwater that accumulated in the bottom of <br /> the excavation over a period of approximately 45 minutes Both sidewall and groundwater <br /> samples from the excavation were reportedly collected from the area immediately below the <br /> former tank location and represent an area of maximum petroleum hydrocarbon <br /> concentration in the soil from leakage or spillage <br /> The soil samples were taken from the capillary fringe area, a semi-saturated unit directly <br /> above the groundwater table Relatively high concentrations of petroleum hydrocarbons <br /> detected in these soils appear to reflect downward migration of petroleum hydrocarbon <br /> compounds through the vadose zone soils (McLaren, 1989x) <br /> The groundwater sample taken from the capillary fringe/groundwater table interface in the <br /> open excavation is semi-quantitative Factors contributing to the samples semi-qualitative <br /> nature may include 1) volatilization of contaminants from the groundwater surface, 2) <br /> adsorbed contaminants on suspended solids from other locations within the excavation, and <br /> 3) globules of petroleum hydrocarbon free product floating on the groundwater surface <br /> In addition to the excavation sidewall soil samples, two composite soil samples were <br /> collected from the excavated soil piles by McLaren personnel Analysis for TPH by EPA <br /> Test Method 8015 (modified) and for aromatic volatile organics by EPA Test Methods 8020 <br /> and 602 were conducted by Enseco Mobile Laboratories Soil and water samples were <br /> also analyzed for organic lead content by the California Department of Health Services <br /> ' approved test method and for total lead concentration by EPA Test Method Results of the <br /> 19150011005 9 <br />