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I in Appendix H Historical TPH concentrations in wells MW-6 through MW-14 and EW-1 are also shown graphically in Figures 5 through 14 (full scale inoculation was completed on Iday 1,500) Between September and December 1994, TPH and BTE&X concentrations decreased in each well at the site except MW-14 Dramatic decreases were observed in off-site wells MW-6 and MW-9 A significant decrease in petroleum hydrocarbon was also observed in EW-1, which at one time had the greatest concentrations of hydrocarbons Both TPH as I BTE&X were reported at Just above the detection limits in samples MW-7, MW-10 and MW-11 I Only the sample from MW-14 was analyzed for EDB, EDB was reported at the detection limit of 0 50 ppb 1,2-Dichloroethane was detected in samples from MW-S, MW-9, MW-13 and MW-14 at concentrations of 2 9 ppb, 24 ppb, 2 5 ppb and 25 ppb, respectively This represents a decrease from the previous sampling in MW-13 and an increase in MW-8, MW- 9 and MW-14 No apparent pattern can be seen from the HVOC concentrations IChloroethane was detected for the first time at the site in MW-9 and MW-14, tetrachloloetliene, a substance used in dry cleaning processes, was detected in MW-7 and MW-13 No other volatile halocaibons were detected in any of the water samples The analytical results are summarized in Table 7 The laboratory results and chain-of-custody are included in Appendix H 5.0 CONCLUSIONS AND RECOMMENDATIONS 51 Hydrocarbon Impacted Gi oundwater I Groundwater elevation has increased (risen) about 25 feet throughout the site since September 1994 (see Table 3) Dunng the pi evious monitoring a 2 foot deci ease «as noted throughout the site Gioundwater elevation fluctuations at the site appear to be in I accordance with seasonal variations of groundwater depth in the region The groundwater flow direction continues to be to the south-southwest I Historically, hydrocarbon concentrations in groundwater samples have fluctuated widely at the site However, towaids the end of 1994 concentrations appear to stabilize and, during the December 1994 sampling, were significantly reduced in most wells Microbiological data from the monitoring wells indicate that bacteria are present in significantly increased numbers Combined with the reduction of hydrocat bons in the vadose zone, we anticipate concentrations in the groundwater to continue a downward trend Samples from MW-11, MW-12 and MW-13 seem to indicate that the hydrocaibon plume Ihas not migrated beyond the known plume boundaries Concentrations of hydrocarbons in GwbgaF qudu Servcv ]nr Quanaly RcFm.VL2 W1 33 GEWQM6 I