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yl yl a x. = y • 17 July 1997 AGE-NC Project No 95-0142 - t 1 ' t i Page 3 of 4 f were detected in samples from each vapor well at concentrations as high,as 40,000 ppb (toluene, , I `I{�T- �. , 4 �� 1) ''r Benzene was detected iii the same sample at a concentration of 29,000 ppb-MTBE was detected in ' samples collected from each vapor well at concentrations'as high as,1,100 ppb (VW-1r) 1 y ry I 4 I TPH-g was detected in the sample collected from well MW-5 at a concentration of 470 ppb BTE&X compounds were detected in the same sample at concentrations as high as 9 2 ppb (benzene) MTBE , was detected in the sample at a concentration of 15 ppb Detectable concentrations of petroleum z hydrocarbons were present in the sample from MW-,4 Analytical results of all ground water samples are summarized in Table 2 - Analyncal,ResuI6 of- Ground Water Samples The laboratory report (MAI Laboratory ) D Nos 78175 through 78181), ' chain-of-custody and QA/QC report are included iii Appendix B t A I 33 ANALYTICAL;RESULTS OF PURGEDWATER SAMPLES I , I4 Detectable concentrations of TPH-g were not present in the sample collected from the barrel of purge water stored on-site However, total xylene was detected at 0 85 ppb The laboratory report (NIAI Laboratory I D No 78182), chain-of-custody and QA/QC report are included in Appendix B r � 1 ' — _ • I a 4.0. SUMMARY 1 CONCLUSIONS r �' Based upon data collected from the site, AGE has made the following conclusions The ground watei surface at thesitehas remained approximately ten feet above the tops of 1'a t the screened casings an`grbund monitoring wells,MW-1 thirough,MW-3 for the past year, therefore;"samples collected from these wells may not be representative of the upper aquifer conditions where the maximum impact of fuel hydrocarbons would be expected ` '1' . ,f ` • ' Ground water,' ftow'direction is generally toward the east in the vicinity of the hydrocarbon release (TK1-90), therefore'wellTMW-5 represent the down-gradient wells at the M ! site ti Detectable concentrations of hydrocarbons were present in both down gradient well`s W-4 and MW-5 Concentrations in both wells have remained constant over the past quarter F { w The highest concentration of dissolved petroleum hydrocarbons were detected in vapor well 4 VW-l; tlocated immediately adjacent 'to the former TK1=90 UST Concentrations of „ ` hydrocarbons detected in the sample collected from this well increased compared,to the previous quarterly samplmgyesults Concentrations'of TPH-4 and BTE&X in the ground water samples collected from vapor Ilk °