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Table 3 is a summary of the depths to ground water and the calculated elevations of the top <br /> of ground water that were gauged on 15 November 1988. The elevations of the top of <br /> ground water are also summarized on Figure 2. First water was encountered at depths <br /> below the ground surface between 36 and 43 feet. The static depth to water has since risen <br /> to between 36 and 37 feet below the top of casing and ground surface. The top of ground <br /> water or potentiometric surface is rather flat. The indicated direction of flow is to the <br /> northeast,but the gradient between MW 1 and MW3 is 0.002. <br /> The stratigraphy beneath Chevron SS 9-1918 is dominated by a thick section of sandy to <br /> silty clay that overlies a well sorted, medium to coarse sand. This sand appears to contain <br /> the ground water and occurs at depths below the ground surface of 36 to 43 feet. This <br /> sand is immediately underlain by an olive gray clay that is very tight and plastic. <br /> Petroleum hydrocarbon contamination was identified in the soils and ground water in each <br /> of the wells except MW l; MW 1 contains no detectable hydrocarbons. The highest <br /> concentrations were encountered in MW3 and MW4 north and within the former tank field. <br /> Concentrations of petroleum hydrocarbons in both the ground water and the soils diminish <br /> at MW2, MW5,and MW6, to the southeast,east, and northeast of the former tank field <br /> respectively. <br /> 3 <br />