ARCHIVED REPORTS XR0007773 - Laserfiche WebLink

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31 January 1997 AGE-NC Project No 95-0142 Page 3 of 4 VW-1) Additionally, MTBE was detected in samples collected from each vapor well at concentration as high as 700 ppb (VW-1) Detectable concentrations of petroleum hydrocarbons were not present in the sample from MW-4 Analytical results of the ground water samples are summarized in Table 2 -Analytical Results of Ground Water Samples The laboratory report (MAI Laboratory I D Nos 72128 through 72132), chain-of-custody and QA/QC report are included in Appendix B 3 3 ANALYTICAL RESULTS OF PURGED WATER SAMPLES Detectable concentrations of petroleum hydrocarbons were not present in the samples collected from the barrels of purge water stored on-site The laboratory report (MAI Laboratory I D No 72133), chain-of-custody and QA/QC report are included in Appendix B 4.0. CONCLUSIONS AND RECOMMENDATIONS 41 CONCLUSIONS Based upon data collected from the site, AGE has the following conclusions • The ground water surface at the site has remained well above the tops of the screened casings in all monitoring wells for the past year Therefore, samples collected from these wells may not be representative of the actual aquifer conditions • The ground water flow direction in the vicinity of the former UST TKI-90 is toward the east, therefore, MW-4 does not represent actual down gradient conditions at the site • Overall, concentrations of hydrocarbons at the site decreased slightly The greatest concentration of dissolved petroleum hydrocarbons were detected in vapor well VW-1, located immediately adjacent to the former TK1-90 UST • Concentrations of toluene, ethylbenzene and xylenes increased in vapor well VW-3, located immediately down-gradient of the former TKI-90 UST This could indicate an unstable hydrocarbon plume at the site 4 2 RECOMMENDATIONS Based upon past and present site conditions, AGE has the following recommendations for your