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' 08 October 2002 AGE-NC Project 99-0570 ' Page 3 of 4 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES TPH-g and TPH-d were detected in two of the ground water samples TPH-g was detected in samples MW-2 and MW-3 at concentrations of 1,500 micrograms per liter (µg/1) and 350 µg/1, ' respectively TPH-d was detected in the same samples at 1,300 µg/I and 210 µg/l, respectively BTEX compounds were detected in sample MW-2 at concentrations as high as 34 µg/l ' (ethylbenzene),benzene concentration in sample MW-2 was 6 8 µg/1 Except for toluene (3 0 µg/1) in sample MW-3, BTEX compounds were not detected in the remaining ground water samples ' MTBE was detected in samples MW-1, MW-2 and MW-3 at 9 7 µg/1, 30 µg/1 and 540 µg/l, respectively by EPA Method 8260 TBA was detected in the sample from well MW-1 at a ' concentration of 7 5 µg/1 No other fuel oxygenates were detected in any of the samples Laboratory results of water samples ' analyzed for petroleum hydrocarbons are summarized in Table 2 The laboratory reports for the quarterly monitoring event(MAI Laboratory ID No 0206465-01 to 05)QA/QC reports and chain-of- custody form are included in Appendix B 4 0. SUMMARY AND CONCLUSIONS ' Based on the findings from this investigation, AGE draws the following conclusions ' Ground water flow direction was towards the northwest from the former dispenser area at a hydraulic gradient of 0 02 feet/feet • MTBE was detected in three ground water samples,with the highest dissolved concentration ' occurring southeast of the dispenser area and the former UST excavation MTBE concentrations in samples MW-2 and MW-3 were above the DHS' Maximum Contaminant Level of 13 µg/1 in drinking water ' TPH and BTEX compounds were detected in two ground water samples at concentrations up to 1,500 µg/1 ' The up gradient well, MW-3, has the highest MTBE concentration and has had increased contaminant concentrations over the last four quarters I Advanced Ge0Environrnental,Inc I R