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L <br /> 09 January 1998 <br /> i AGE-NC Project No. 95-0185 <br /> ' Page 3 of 4 <br /> ' and MW-4 at concentrations of 8,200 parts per billion (ppb, reported as micrograms per liter), 110 <br /> ppb, 520 ppb and 19,000 ppb,respectively. TPH-g was detected in the ground water samples from <br /> wells MW-1 and well MW-4 at a concentrations of 330 ppb and 220 ppb, respectively. The 110 ppb <br /> TPH-d is the first detected petroleum hydrocarbon in monitoring well MW-2. <br /> BTE&X compounds were detected in samples collected from wells MW-1 and MW-4 at <br /> concentrations as high as 5.0 ppb (benzene, MW- 4). <br /> MTBE was detected by EPA method 8260m in the sample collected from wells MW-4 at 6.5 ppb <br /> ' and tert butanol was detected in the samples collected from wells MWA and MW-4 at <br /> concentrations of 27 ppb and 8.5 ppb, respectively. <br /> Analytical results of monitoring well ground water samples are summarized in Table 2 for analyses <br /> by EPA Methods 8015M and 8020, and Table 3 for analyses by EPA Method 8260. The laboratory <br /> report (MAI Laboratory T.D. Nos. 82612 to 82615), and chain-of-custody form are included in <br /> Appendix B. <br /> M4.0. SUMMARY AND CONCLUSIONS <br /> ' The following conclusions were drawn from the results of this investigation: <br /> • Ground water elevation at the site decreased an average 3.44 feet since the last quarterly <br /> monitoring event. <br /> • Concentrations of TPH-g and BTE&X hydrocarbons have fluctuated over a wide range in <br /> ' MW-1 and MW-4, and have increased slightly in MW-2 and MW-3. <br /> • Well MW-2 appears to be located at the southern edge of the dissolved TPH-d plume and <br /> ' monitoring well MW-3 lies near the western margin of the plume. ' <br /> The northern and eastern margins of the dissolved phase plume have not been fully <br /> delineated. <br /> 5.0. RECOMMENDATIONS <br /> Based upon data collected at the site, AGE-recommends the following; <br />' To reduce the concentration of TPH-d in theg round water at the site AGE recommends an <br /> interim active remediation of the remaining petroleum hydrocarbon-impacted soil. Removal <br /> Advanced GeoEnvtronmental,Inc. <br />