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V - 09 October 2003 AGE-NC Project 99-0570 ' Page 3 of 4 ' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES ' TPH-g was detected In samples MW-1,MW-2 and MW-4 at concentrations of 110 micrograms per liter (µg/1), 2,200 µg/1 and740 µg/l, respectively TPH--d was detected in samples MW-2 at 3 6 milligrams per liter(mg/1) ' BTEX compounds were detected at a maximum concentration of 260 ug/1 (xylene), while benzene was detected in sample MW-2 at a concentration of 14 ug/I BTEX compounds were not detected in the remaining ground water samples MTBE was detected in samples MW-1, MW-2 and MW-4 at 6 7 gg/l, 37 µg/1 and 190 µg/l, respectively 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 (CTEL Laboratory ID No 0305113-1 to 5) QA/QC reports and chain-of-custody form are included in Appendix B lie 4.0. SUMMARY AND CONCLUSIONS IBased on the findings from this investigation, AGE draws the following conclusions • Ground water flow direction was towards the north from the former dispenser area at a I hydraulic gradient of 0 02 feet/feet This flow direction and gradient are similar to previous monitoring events • The benzene concentrations in samples MW-2 exceed the DHS Maximum Contaminant ' Level (MCL) for drinking water • MTBE was detected in three ground water samples,with the highest dissolved concentration ' occurring northeast of the dispenser area(MW-4) MTBE concentrations In samples MW-2 and MW-4 were above the DHS' MCL of 13 µg/1 for drinking water and the MTBE concentration of 6 7 µg/1 in well MW-1 exceeds the DHS Secondary MCL • Petroleum hydrocarbons (TPH/BTEX) increase significantly in well MW-2 relative to the previous quarters In addition, TPH-g and MTBE were detected in the sample from well I MW-4 for the first event and TPH-g was detected in the sample from well MW-1 after three consecutive quarter of non-detect However,petroleum hydrocarbons and MTBE were non detected in the sample from well MW-3, after five successive quarters I • Advanced GeoEnvironlnefntal,Inc I