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05 December 2003 <br /> AGE-NC-99-0570 <br /> Page 3 of 4 <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in samples MW-2 and MW-4 at concentrations of 220 micrograms per liter <br /> (µg/1) and 300 gg/I, respectively <br /> The BTEX compound ethylbenzene was detected at a maximum concentration of 12 ug/1 in samples <br /> collected from MW-2 No other BTEX compounds were detected at or above laboratory reporting <br /> limits in the remaining ground water samples <br /> MTBE was detected in samples MW-1, MW-2, MW-3 and MW-4 at 8 Ogg/1, 7 5 4g/1, 33 µg/1 and <br /> 280 gg/l, respectively No other fuel oxygenates were detected in any of the samples <br /> Laboratory results of water samples analyzed for petroleum hydrocarbons are summarized in <br /> Table 2 The laboratory reports for the quarterly monitoring event(CTEL Laboratory ID No 0309- <br /> 044-1 to 5) QA/QC reports and chain-of-custody form are included in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> • � A�� <br /> Based on the findings from this investigation., AGE draws the following conclusions <br /> Ground water flow direction was towards the north to �from the former dispenser <br /> area at a hydraulic gradient of 0 02 feet/feet This flow direction and gradient are similar to <br /> previous monitoring events <br /> • MTBE was detected in four ground water samples,with the highest dissolved concentration <br /> occurring northeast of the dispenser area(MW-4) MTBE concentrations in samples MW-3 <br /> and MW-4 were above the DHS' MCL of 13 gg/I for drinking water and the MTBE <br /> concentrations in wells MW-I and MW-2 exceed the DHS Secondary MCL. <br /> • Petroleum hydrocarbons (TPH/BTEX)decreased significantly in well MW-2 relative to the <br /> previous quarter In addition,TPH-g and MTBE were detected in the sample from well MW- <br /> 4 for the second consecutive quarter TPH-g was not detected in the sample from well MW-I <br /> for the fourth time is five sampling events <br /> 5.0. RECOMMENDATIONS <br /> Based upon the investigation results during the third quarter 2003, AGE recommends <br /> • Continued quarterly ground water monitoring <br /> Advanced GeoEnvironmental,Inc <br />