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' 17 April 2002 <br /> . AGE-NC Project No 98-0521 <br /> ' Page 3 of 4 <br /> 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> The results of the March 2002 monitoring event are as follows <br /> • <br /> TPH-g was not detected in the samples collected from monitoring wells MW-1 and MW-3 <br /> TPH-g was detected in the samples collected from momtonng wells MW-2 and MW-4 at <br /> ' concentrations of 54 micrograms per liter(gg/I) and 1,400 µg/l, respectively <br /> • BTEX compounds were detected only in the samples collected from monitoring wells MW-2 <br /> and MW-4, the maximum BTEX concentrations were detected in the sample from MW-4 <br /> at 250 µg/I benzene, 4 9 gg/1 toluene, 35 µg/1 ethylbenzene and 73 gg/l total xylenes <br /> •_ MTBE was detected by EPA Method 8020 in ground water samples MW-1, MW-2 and <br /> MW-4 at concentrations of 18µg/l,370 gg/1 and 1,600µg/1,respectively,the MTBE results <br /> were confirmed by EPA method 8260 Modified at 21 µg/1, 430 µg/1 and 1,600 µg11, <br /> respectively <br /> • TBA was detected in the sample collected from monitoring well MW-4 at a concentration <br /> of 290 µg/1 No other fuel oxygenates were detected in these samples <br /> lie <br /> Analytical results from the monitoring well ground water samples are summarized in Tables 2 and 3 <br /> ' The laboratory report (MAI Lab IDs 0203258-001 through 0203258-004),QA/QC and chain-of- <br /> custody are included in Appendix B <br /> ' 4.0. SUMMARY AND CONCLUSIONS <br /> ' The following conclusions were drawn from the results of this investigation <br /> • Ground water at the site was encountered at approximately 7 8 feet bsg The prevailing <br /> - ground water flow direction at the site has been generally toward the northeast for six <br /> monitoring events The ground water hydraulic gradient was estimated to be 0 011 foot/foot <br /> - Dissolved phase hydrocarbons, including TPH-g, BTEX and MTBE, were present in the <br /> ' samples from wells MW-2, located down-gradient of the former UST area, and MW-4, <br /> located within the former UST area MTBE was also detected in the sample collected from <br /> ' MW-1, cross-gradient from the former UST area <br /> • Additional site assessment will be required to fully assess the down-gradient and vertical <br /> i ' extent of the dissolved hydrocarbons and MTBE <br /> Advanced GeoEnvironmental,Inc <br />