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. 07 November 2000 <br /> AGE-NC Project No. 98-0520 <br /> ' Page 3 of 4 <br /> ' respectively. Maximum ethylbenzene and xylene concentrations were also detected in the sample <br /> from MW-5 at 650 µg11 and 700 µg/l, respectively. <br /> ' The fuel oxygenate TBA was detected by EPA Method 8260B in four of the ground water samples <br /> (MW-2 to MW-5)collected at concentrations ranging from 40 µg/l in MW-4 to 170 µg/1 in MW-3. <br /> tMTBE and 1,2-DCA were not detected above laboratory reporting limits in the ground water <br /> samples collected. <br /> ' Analytical results of ground water samples are summarized on Table 2. The laboratory report(MAI <br /> Lab I.D. No. 47034 through 47038) and chain-of-custody forms are included in Appendix B. <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based upon data collected from'the site, AGE concludes: <br /> • Depth to ground water at the site averaged approximately 21 feet bsg on 07 September 2000. <br /> • On 07 September 2000 the ground water elevation at the site averaged approximately 15.55 <br /> feet above mean sea level and flowed toward the west under an average gradient of 0.0009 <br /> eft. <br /> • TPH-g concentration declined in groundwater samples from MW-4 and MW-5(former UST <br /> area), but TPH-g concentration increased in samples from MW-2 and MW-3 from the <br /> previous quarter monitoring. <br /> • TPH-g and BTEX compounds were detected in all five ground water monitoring wells on- <br /> site.Further lateral definition is necessary to determine the horizontal extent of hydrocarbon- <br /> impact to ground water. <br /> 9 TBA was detected in four of the five ground water monitoring wells at concentrations as high <br /> as 170 4g11. <br /> 5.0. RECOMMENDATIONS <br /> Based upon data collected from the site, AGE recommends: <br /> • Further site assessment to determine the lateral extent of petroleum hydrocarbon-impacted <br /> and TBA-impacted ground water. <br /> Advanced GeoEnvironmental,Inc. <br /> S� <br />