SITE INFORMATION AND CORRESPONDENCE

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Lead was detected in all groundwater samples at concentrations between 0.008 parts per million (ppm; MW-10) and 0.013 ppm (MW-13). The analytical results are summarized in Table 3. The laboratory report and chain-of-custody are included in Appendix A. 1,2-Dichloroethane was detected in EW-1, MW-13 and MW-14 at concentrations of 33 ppb, 14 ppb and 93 ppb, respectively. No other volatile balocarbons were detected in any of the water samples. The analytical results of the volatile halocarbons are summarized in Table 4. The laboratory report and chain-of-custody are included in Appendix A. 5.0 CONCLUSIONS AND RECOMMENDATIONS 5.1 Groundwater Depth and Flow Direction The depth to groundwater has decreased approximately 2 feet throughout the site area since measurements were made in September of 1993. This is in accordance with seasonal variations of groundwater depth in the region. The groundwater flow direction continues to be to the south-southwest. 5.2 Petroleum Hydrocarbon Contamination There have been several changes in the distribution of contaminants since the September 1993 sampling event. Concentrations of TPH and BTE&X have decreased significantly in both MW-14 and EW-1. These two wells are nearest the center of the plume of soil contamination, and groundwater contamination continues to be greater in these wells. In contrast, three wells that are located beyond the limits of the soil plume exhibited increases in groundwater contamination in this quarter. These include two down-gradient wells (MW-7 and MW-11) and one up-gradient well (MW-10). No contamination was detected in soil samples when these wells were drilled. None of these wells were contaminated in the September event, although contamination has been detected in all of these wells in one or more previous monitoring events. It is therefore difficult to discern a consistent pattern of contamination in the data, but it does not appear that fluctuations in groundwater contamination are related to seasonal fluctuations in the water table. 5.3 Volatile Halocarbon Contamination For the second consecutive quarter, 1,2-Dichloroethane (1,2-DCA) was detected only in samples from EW-1, MW-13 and MW-14. The concentration in each well has increased since the previous quarter. In June of 1993, Sun-Tech Environmental reported several volatile halocarbons in MW-6, MW-10, MW-11 and MW-12 in addition to EW-1, MW-13 and MW-14. It appears that although the number of wells containing detectable concentrations of halocarbons has Cmbpol AedServ:va,Inc. 12 13M.0. MM QR