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1 <br /> 10 December 2001 <br /> AGE-NC Project No 98-0465 <br /> Page 3 of 4 <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> Each sample was analyzed for TPH-g, TPH-d, BTEX, and for the suite of five oxygenated fuel <br /> ' additives TPH-g, TPH-d and BTEX were not detected at concentrations at or above the laboratory <br /> reporting limits in any of the ground water samples <br /> ' MTBE was detected by EPA Method 8020 in the ground water samples collected fromMW 1,MW3, <br /> and MW4 at concentrations of 35 µg/1, 55 µg/1 and 5 6 µg11, respectively MTBE detections were <br /> confirmed in the samples by EPA Method 8260 at concentrations of 43 gg/l, 60 µg/1 and 7 8 µg/1, <br /> ' respectively No other fuel oxygenated compounds were detected in the ground water analyses <br /> Figure 4 illustrates the approximate extent of MTBE-Impacted ground water <br /> ' Analytical results of water samples collected during October 2001 are summarized on Table 2, the <br /> laboratory report (MAI Lab No 81660 through 81663), QA/QC report and chain-of-custody form <br /> are Included in Appendix B <br /> ' . 4.0. SUMMARY AND CONCLUSIONS <br /> The following conclusions were drawn from the results of this investigation <br /> ' 0 The ground water elevations ranged from 9 60 to 9 71 feet below MSL Ground water is <br /> generally flowing toward the northwest under an average gradient of 0 001 feet/feet The <br /> relative ground water elevation at the site decreased an average 1 64 feet between the July <br /> 2001 and October 2001 monitoring events <br /> G Concentrations of dissolved MTBE in samples collected from MW-1 and MW-3 have <br /> ' remained relatively stable since ground water monitoring began In July 2000 <br /> U 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 to northwest, east or south <br /> ' 5.0. RECOMMENDATIONS <br /> Based on the findings of this investigation, AGE recommends continued quarterly monitoring of the <br /> ' ground water monitoring wells The next monitoring event should be performed in January 2002 <br /> Additionally, AGE is preparing a work plan to assess the lateral and vertical extent of MTBE- <br /> Impacted ground water <br /> 1 <br /> i <br /> Advanced GcoEnvu'onmental,Inc <br /> 1 <br />