ARCHIVED REPORTS XR0001705 - Laserfiche WebLink

Home Browse Search

1`h • 10 March 2000 AGE-NC Project No. 95-0109 Page 3 of 4 3.2. MICROBIOLOGICAL ACTNITY IN GROUND WATER Concentrations of dissolved oxygen generally increased slightly between the September 1999 and January 2000 monitoring events in water samples collected from the wells. General subpopulations decreased slightly in MW-14 and increased in MW-9 while selective subpopulations increased in both samples. Nutrient concentrations generally increased slightly or remained stable. Field measurement for indicators of microbiological activity are summarized on Table 2; microbiological and physicochemical analytical results are summarized on Table 3. The laboratory report (A. Keith Kaufman February 1, 2000) and chain-of-custody form are included in Appendix B. 3.3. PETROLEUM HYDROCARBON-IMPACTED GROUND WATER Petroleum hydrocarbons were detected in ground water samples from four of the seven wells sampled. TPH-g concentrations ranged up to 2,400 parts per billion (ppb; reported as micrograms per liter). Benzene, toluene, ethylbenzene and xylenes were detected at concentrations as high as 67 ppb, 31 ppb, 50 ppb and 180 ppb, respectively. The highest concentrations were detected in samples collected from MW-8 and MW-14. Only TPH-g was detected in the sample collected from MW-7. . Petroleum hydrocarbons were not detected in the samples collected from MW-6, MW-11 and MW- 12. The results of analysis by EPA Method 8015m/602 for the January 2000 monitoring event are presented on Table 4. Historical analytical results by EPA Method 8015m/602 are summarized in Table 5. Graphs illustrating the concentrations of TPH-g and benzene over time are presented in Appendix C. TBA was detected in the samples collected from MW-8 and MW-9 at concentrations of 27 ppb and 16 ppb, respectively. Other oxygenated compounds were not detected in the samples collected. 1,2- Dichloroethane(1,2-DCA)was detected in MW-8, MW-9 and MW-14 at concentrations of 5.2 ppb, 25 ppb and 12 ppb, respectively. Twelve additional analytes, detected by EPA Method 8260, are noted in Table 6.The laboratory report(MAI Laboratory I. D.Nos. 29315 through 29321) and chain- of-custody forms are included in Appendix B. 4.0. DISCUSSION AND CONCLUSIONS Based upon data collected from the site, AGE finds: • Ground water elevation increased at the site during the fourth quarter of 1999. Ground water flow direction continues to be toward the south-southwest at the site. • Hydrocarbon concentrations in ground water generally decreased at the site between the September 1999 and January 2000 sampling events. Advanced GeolEnvironmental,Inc.