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1 - <br /> 29 December 1999 <br /> AGE-NC Project No 96-0229 <br />' Page 3 of 5 <br />' water elevation at the site decreased an average 1 58 feet between the July 1999 and the October <br /> 1999 ground water monitoring events The ground water elevation data for MW-1 through MW-10 <br /> during the October 1999 ground water monitoring event is depicted in Figure 3 <br />' Ground water monitoring data collected in the area of wells MW-I through MW-10 indicated that <br /> the ground water flow direction was generally toward the northeast at a gradient of 0 003 ft/ft, or <br />' approximately 15 feet per mile (Figure 3) Ground water was approximately 20 to 22 feet above the <br /> screen intervals at MW-1 and MW 10-B Therefore these wells are "drowned", and yield samples <br /> more representative of deeper ground water conditions <br /> I <br /> 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> I <br /> A total often ground water samples were submitted to aDHS-certified laboratory in October 1999 <br /> TPH-g was detected in water samples collected from wells MW-1, MW-2,MW-3, MW-6 and MW- <br /> 7 at concentrations ranging as high as 60,000 micrograms per liter(µg/I) <br /> BTEX compounds were detected in ground water samples collected from wells MW-1,MW-2,MW- <br /> 3,MW-6, and MW-7 at concentrations ranging as high as 8,900 Ftg/l (benzene, MW-1) MTBE was <br /> detected in ground water samples collected from wells MW-1, MW-7 and MW-8 at concentrations <br />' ranging as high as 760�cg/l <br /> MTBE was confirmed utilizing EPA Method 8260 in samples collected from wells MW-1, MW-2, <br />' MW-6, MW-7 and MW-8 at concentrations ranging as high as 320 ggll, TBA was detected in <br /> ground water samples collected from well MW-7 at a concentration of 27 µg/1 No other fuel <br /> oxygenated additives were detected above laboratory reporting limits from the analyzed samples <br /> Analytical results of the ground water samples are summarized in Table 2 The laboratory reports <br /> (Castle Analytical Laboratory Reference No 2534 and McCampbell Analytical Inc I D No 23541 <br />' through 23550) and chain-of-custody forms are presented in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The implications from the findings of the October 1999 investigation are <br /> • The dissolved BTEX and MTBEP lume is at least 20 feet thick in the area of MW-1 and <br /> MW-2,with depth,the dissolved BTEX and MTBE plume grades from lower concentrations <br /> to higher concentrations <br /> • • The highest benzene and MTBE concentrations were encountered in the ground water <br /> Advanced CeoEnvironmental,Inc <br />