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i <br /> Andyses <br /> Soil and ground water samples collected during the various <br /> investigations were analyzed for some or all of the following <br /> constituents of concern: <br /> • Total Petroleum Hydrocarbons (TPH) as Gasoline and Diesel; <br />' • Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX); <br />' • Ethylene Dibromide (EDB), <br /> • Total Lead and Organic Lead; and <br />' • Coliform Bacteria. <br /> The results of the laboratory analyses for these constituents of <br />' concern are discussed below <br /> TPH and BTEX. The laboratory analyses summarized in Tables 4-1 <br />' and 4-2 indicate the presence of gasoline and associated compounds <br /> (BTEX) in both soil and ground water. The extent of TPH and BTEX <br /> compounds in soils was delineated during the investigations <br /> conducted by both Kleinfelder and ERM-West. The lateral and <br /> vertical extent of TPH and BTEX in soil is limited to a localized area <br /> in the vicinity of the former tank, in a zone between approximately <br />' 6 and 11 feet bgs (see Figure 4-2). This zone of affected sods is above <br /> the clay-sand contact but below the ground water potentiometric <br /> surface. <br />' The extent of TPH and BTEX in ground water is also limited. The <br /> maximum concentrations of TPH-gasoline and benzene detected in <br /> ground water are illustrated in Figure 4-3. The highest <br />' concentrations of these compounds detected were in ground water <br /> samples collected at soil gas probe location M and monitoring wells <br /> MW4 and MWS. The ground water sample from location M was a <br /> one-time sampling event conducted in March 1990. The highest <br /> concentrations of TPH-gasoline and benzene detected in ground <br /> water in MW4 and MW5 were from samples collected in Apnl 1991. <br />' However, the results of quarterly ground water samples collected <br /> from monitoring wells MW4 and MW5 since April 1991 have shown a <br /> steady decline in the concentrations of TPH-gasoline and benzene in <br /> ground water. Table 4-3 presents a summary of the quarterly ground <br /> water sample results for Site #1. The concentrations of TPH-gasoline <br /> and benzene detected in MW5 have decreased significantly over time, <br />' and the most recent samples collected from MW4 in December 1992 <br /> and March 1993 were non-detect. Based on the ground water data, <br /> 4-4 <br />