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�h <br /> i I 1 <br /> 31 July 2003 <br /> AGE-NC Project No 98-0465 <br /> Page 3 of 4 <br /> Wells MW through MW4 and wells MW2 through MW7, on the adjacent site were used'to Infer <br /> groundwater flow direction and gradient The groundwater flow direction was inferred to be toward <br /> the north at an average gradient of 0 0009 feet/feet Figure 3 Illustrates the contoured ground water <br /> ` elevation's as measured on 22 May 2003 <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g, TPH-d and BTEX were not detected at concentrations at or above the laboratory reporting <br /> limits In any of the ground water samples <br /> MTBE was detected In samples collected from MW1, MW3 and MW4 by EPA Method 8260B at <br /> concentrations of 640µg/l, 8 5 µg/1 and 1 1 µg/l,respectively No other fuel oxygenated compounds <br /> were detected In the ground water analyses at or above laboratory detection limits Figure 4 <br /> Illustrates the approximate extent of MTBE-Impacted ground water <br /> Analytical results of water samples collected during May 2003 are summarized on Table 2 the <br /> Yt p g Y <br /> laboratory report(MAI Lab IDs 0305373-001 through 0305373-004), QA/QC report and chain-of- <br /> custody form are included In Appendix C <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based on the findings from this Investigation, AGE concludes <br /> • The ground water elevations on-site ranged from 7 20 to 7 31 feet below MSL Ground water <br /> E was Inferred to be towards the north under an average gradient of 0 0009 feet/feet Ground <br /> water gradient and direction remained stable between the 'March'2002 and May 2003 <br /> monitoring events <br /> E0 TPH-g, TPH-d and BTEX were not detected In the ground water samples collected and <br /> analyzed during the first quarter 2003 <br /> • MTBE was detected In samples collected from MW1,MW3 and MW4 at concentrations of <br /> 640 µg/1, 8 5 µg/1 and 1 1 µg/l, respectively Detected concentrations of MTBE In wells i <br /> MW 1,MW3 and MW4 have remained relatively stable compared to the previous monitoring 1 ' <br /> event ' <br /> • The lateral extent of MTBE-Impacted ground water has,been defined to the northeast of the <br /> ,former UST area, but not toward the west-northwest, east`or south <br /> i~I <br /> I <br /> Advanced GeoEnvironmental,Inc <br /> , I i <br /> i <br />