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24 October 2003 <br /> AGE-NC Project No. 98-0497 <br /> Page 3 of 4 <br /> 3.2. ANALYTICAL RESULTS FROM GROUND WATER SAMPLES <br /> The analytical results from the 16 June 2003 ground water sampling event are as follows: <br /> • TPH-g was detected in well MW-1 at concentration of 480 micrograms per liter(µg/1). The <br /> laboratory report noted that strongly-aged gasoline or diesel compounds were significant; <br /> • TPH-d was detected at a concentration of 14,000 gg/1 in MW-1; <br /> • Toluene and total xylenes were detected in the sample from well MW-1 at concentrations <br /> of 0.73 µg/1 and 1.8 µg11, respectively; <br /> • Fuel additives were not detected in the five ground water samples analyzed. <br /> 'r Laboratory results of water samples analyzed for petroleum hydrocarbons are summarized in <br /> Table 2. Copies of the laboratory reports for the quarterly monitoring event(MAI Lab IDs 0306350- <br /> 001 through 0306350-005), QA/QC reports and chain-of-custody form are in. Appendix B. <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The findings of the 16 June 2003 ground water monitoring event include the following: <br /> • Measured ground water elevation was approximately 39.0 feet below MSL, and was within <br /> the screened interval of each monitoring well. Ground water flow direction near the former <br /> UST location was to the east-northeast with an average gradient of 0.002 foot/foot. <br /> — Historically, flow direction at the site has been toward the east or has had no observable <br /> gradient. <br /> • Contamination by TPH-g, TPH-d, toluene and total xylenes was encountered in the ground <br /> water sample collected and analyzed from MWA. The detected concentrations ofTPH-d in <br /> samples collected from MW-1 have fluctuated significantly during the past six monitoring <br /> — events.Prior to June 2002,the TPH-d concentrations in well MW-1 had exhibited an overall <br /> declining trend. TPH-g and TPH-d were not detected in wells MW-2 through MW-5. <br /> • TPH-g, TPH-d, BTEX compounds and fuel additives were not detected in ground water <br /> samples analyzed from wells MW-2 through MW-5. <br /> • The hydrocarbon-impacted ground water plume appears to be limited to the area immediately <br /> surrounding MWA. The inferred areal extent of hydrocarbon-impacted ground water is <br /> illustrated in Figure 4. <br /> Advanced Geo Environmental,Inc. <br />