ARCHIVED REPORTS XR0001722 - Laserfiche WebLink

Home Browse Search

. 18 April 1997 AGE-NC-95-0109 Page 3 of 5 microbiological data for ground water are summarized on Table 2 and Table 3. The laboratory report (A. Keith Kaufman - March 31, 1997) and chain-of custody form are included in Appendix B. 3.3. PETROLEUM HYDROCARBON-IMPACTED GROUND WATER During the March 1997 sampling event, petroleum hydrocarbons were detected in ground water samples from seven of the fifteen wells sampled. TPH-g concentrations ranged from below laboratory method detection limits to 2,900 parts per billion(ppb; reported as micrograms per liter). BTE&X were detected at concentrations as high as 9.7 ppb benzene (MW-1), 9.2 ppb toluene (MW- 14), 9.3 ppb ethylbenzene (MW-9), and 200 ppb xylenes (MW-14). TPH-g and BTE&X were not detected in samples collected from MW-2, MW-3, MW-6, MW-7, MW-10, MW-11, MW-12 and MW-13 during the March 1997 sampling. Charts 1 - 6 (Appendix D) illustrate benzene concentrations verses time for monitoring wells MW-6, MW-8, MW-9, MW-10, MW-14 and EW-1. EDB was detected in the sample from MW-14 at the detection limit of 0.50 ppb. 1,2-dichloroethane was detected in samples from MW-8, MW-9, MW-13 and MW-14 at concentrations of 1.2 ppb, 2.2 ppb, 1.3 ppb and 5.7 ppb, respectively, a concentration increase in two of seven wells compared to the previous monitoring results. Chloroethane, I,2-dichloropropane, tetrachloroethene and other volatile halocarbons were not detected in any of the water samples analyzed. Analytical results of ground water samples are summarized on Tables 4 and 5. The laboratory report (MAI Laboratory 1. D. Nos. 74562 through 74576) and chain-of-custody forms are included in Appendix C. 4.0. CONCLUSIONS AND RECOMMENDATIONS 4.1. CONCLUSIONS Based upon data collected during the March 1997 sampling event, AGE has the following conclusions: • Petroleum hydrocarbons were not detected in wells MW-2, MW-3, MW-6, MW-7, MW-10, MW-11, MW-12 and MW-13, indicating that the hydrocarbon plume has not migrated beyond the known plume boundaries. • TPH-g and benzene concentrations decreased in each well except for TPH-g in MW-1 between the December 1996 and March 1997 monitoring events. TPH-g concentrations increased in MW-1 compared to the 1991 monitoring event,although benzene concentrations decreased significantly during the same time span. . 0 Concentrations of 1,2-Dichloroethane decreased in three wells, increased in two wells and