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. 14 October 1997 AGE-NC Project No. 95-0106 Page 3 of 4 dichloroethene in MW-4. BTE&X concentrations detected by EPA Method 8260 were similar to the concentrations detected by EPA Method 8020.The BTE&X concentrations detected by EPA Method 8260 are presented in Table 3. Oxygenated volatile organic compounds were not detected in any of the ground water samples. Analytical results of ground water samples are summarized on Table 2. The laboratory report (MAI Laboratory ID 80569 through 80574) and chain-of custody are in Appendix B. 4..0. SUMMARY/CONCLUSIONS The following conclusions were drawn from the results of this investigation: • On 05 September 1997, ground water flow direction at the site was generally convexly toward the north. Based on data from other sites in the area, it is likely that the flow direction varies seasonally from northeast to northwest. • Petroleum hydrocarbons were detected only in wells MW-4, located down-gradient (north) of the former UST excavation, and in MW-1 located near the former UST excavation. • Suspected MTBE, detected in MW-4, was not confirmed by EPA Method 8260, however, low concentrations of vinyl acetate were detected in both MW-1 and MW-4, and a low concentration of 1,2-dichloroethene was detected in MW-4. • Maximum contaminant levels (MCLS) have not been established for vinyl acetate. The 4.4 ppb 1,2-DCA detected in MW-4 exceeds the State Department of Health Services 0.5 ppb maximum contaminant level (MCL) for that compound. • Oxygenated volatile organic compounds were not present at detectable concentrations in any of the ground water samples. • Analytical data from well MW-3 limits the extent of dissolved hydrocarbons toward the northeastward of the site. Analytical data from monitoring well MW-5 limits the extent of dissolved hydrocarbons westward of the site. • In general, most analytes detected in the ground water samples have declined by approximately one order of magnitude or more since the first round of sampling in July 1996. Benzene in wells MWl and MW4, while currently at lower concentrations than originally detected, have not demonstrated quite as large a reduction in concentration. Advanced GeoEnvironmental,Inc.