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, <br /> 10 September 2001 <br /> AGE-NC Project No 95-0142 <br />' Page 3 of 4 <br />' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in samples collected from wells MW-6, VW-1, VW-3 and-VW-4 at , <br />' concentrations of 2,900 micrograms per liter (ug/l), 160,0001.cg/l, 2,700,ug/l and 98 /.tg/l, <br /> respectively Benzene was reported in samples collected from wells MW-6, VW-1 and VW-3 at <br /> concentrations of l l Ag/l,23,000 4el and 110,ug/l, respectively Toluene, ethylbenzene and xylenes <br />' were variously detected in the same samples at concentrations as high as 34,000 ,ug/l (toluene in <br /> VW-1) <br />' MTBE was detected by EPA Method 8020 in wells MW-7 and VW-2 and VW-4 at concentrations <br /> of 8 7 ,ugll, 10 µg11, 9 7 µg11, respectively MTBE was detected by EPA Method 8260 in wells <br /> MW-5,MW-7 and VW-1,VW-2,VW-3 and VW-4 at concentrations of 3 0µg/l, 6 9 ,ug/l, 460 µg/l, <br />' <br /> 12 4g/l, 100µg1 1 and 8 0,ug/l, respectively MTBE was the only oxygenated fuel additive detected <br /> in the ground water samples this quarter <br />' The analytical results are summarized on Tables 2 and 3 The laboratory report (MAI Laboratory <br /> I D Nos 67589 through 67597), quality assurance and quality control (QA/QC)report and chain-of- <br /> custody form are included in Appendix B <br /> 1 4.0. CONCLUSIONS <br /> Based upon data collected from the site during the current and preceding ground water monitoring <br />' events, AGE concludes <br /> • Ground water flow direction appeared to be toward the northwest in the area defined by the <br /> shallow-screened well network on-site and toward the northwest on-site <br /> • The highest concentration of dissolved petroleum hydrocarbons continues to be in the area <br />' the former location of TK1-90 UST <br /> • Low concentration BTEX compounds and MTBE were reported in samples collected from <br /> vapor well VW-4, which is located in the current down-gradient direction from the former <br />' location of TK1-90 UST, the area with the known highest concentration of dissolved <br /> petroleum hydrocarbons <br />' 0 TPH-g and BTEX concentrations were reduced in the samples collected from the deep <br /> screened well MW-6 (screened 70 to 80 feet bsg) Presently, MW-6 is screened <br /> approximately 45 feet below the surface of first-encountered ground water <br />