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4.0 DISCUSSION AND RECOMMENDATIONS- <br /> 4 1 <br /> ECOMMENDATIONS41 DISCUSSION <br /> The following discussion is based on the data collected to date- <br /> Ground water flow beneath the site is generally to the south - southwest with a gentle <br />' gradient and any contaminants present in the ground water will likely rmgrate this <br /> direction <br />' BTEX were detected in the ground water samples from an of the <br /> • TPH-D, and a at gr p y <br />' wells during the fourth quarter 1993. <br /> • Remediation by excavation and disposal of impacted soil was completed in 1987. <br /> Additional site investigation and two years of ground water monitoring have been <br /> conducted at the site during the period of 1990 through 1993. <br />' The additional investigations in the unsaturated soil zone at the site did not Hind any <br /> potential source areas for hydrocarbons ESE concludes that the overexcavatnon <br />' performed adequately removed the impacted soil <br />' Ground water monitoring at the site has indicated that sporadic, minor "hits" of TPH- <br /> D and BTX that have been reported during a single monitoring event have not been <br />' verified in previous or subsequent events (Table 2) Table 3 - Regulatory Threshold <br /> Comparison, compares the maximum BTEX results to state and federal MCLS and <br />' Taste and Odor Threshold. The comparison reveals that of the detectable <br /> concentrations of BTX found, only benzene, found at a concentration of 1.3 ug/L in <br />' ground water from MW-2 (a cross gradient well) during one event exceeds the MCL <br /> of 1 ug/L The occurrence of benzene in this well has not been verified in four <br /> subsequent quarters of monitoring <br /> Environmental science <br /> F'\6935186\4gmr 93 6 &Engineering, Inc <br /> 1 <br />