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f <br /> 2.3 DISCUSSION <br /> Results of the shallow vapor samples indicate that the soil from <br /> 3 to 23 feet below land surface does not contain significant <br /> hydrocarbon levels. <br /> E <br /> The absence of hydrocarbon vapor in the soil at the site suggests <br /> that recently increasing contamination found in the ground water <br />` did not emanate from the confines of the site. The apparent <br /> Product line leak in November 1985, was followed by excavation of <br /> the site and removal of contaminated soils surrounding the tanks <br /> and line trenches. The SVCA results indicate that any soil <br /> contamination from the on-site leak was either removed during <br /> excavation or naturally biodegraded in the past 2 years. At the <br /> time of excavation, the tanks were noted to be in good condition <br /> (GTI 1986) . <br /> Subsequent welI. monitoring has shown decreasing contaminant <br /> levels in wells '2 and 3 located on the do <br /> wngradient borderN <br /> Of the site and in the former tank ,field, respectively. 'hisEr <br /> Suggests that through biodegradation and/or dilution, than <br /> constituents introduced to t' i` . <br /> f ground water via on-site losses <br /> .have dissipated. Well number;:`. however, located on the <br /> upgradient border of the site (SW) has recently exhibited higher <br /> hydrocarbon <br /> concentrations. Base <br /> und on available data it seems <br /> reasonable that these newly elicited contaminant levels are the <br /> result of downgradient site losses which occurr <br /> s ed 2 years prior. ' <br /> This data could, however, suggest that an off-site contaminant <br /> i <br /> plume is movin <br /> .onto thesite influenced by the local <br /> northeasterly- <br /> • _ $ - _ ground-water gradient, <br /> s , <br /> �r <br /> EXXON9:84L <br /> r <br />