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22 March 2001 <br /> AGE-NC Project No 96-0229 <br /> Page 3 of 5 <br /> contoured In Figure 3 <br /> The general ground water gradient at the site was calculated to be approximately 0 004 ft/ft or <br /> approximately 21 feet per mile and directed towards the northeast The ground water surface <br /> elevation at the site Is approximately 20 to 22 feet above the slotted screen intervals In wells MW-1 <br /> and MW-10B <br /> 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> A total of eleven ground water samples were submitted to a DHS-certified laboratory TPH-g was <br /> detected in water samples collected from wells MW-1, MW-2, MW-3, MW-6 and MW-7 at <br /> concentrations ranging between 2,200 and 82,000 micrograms per liter(,ug/1) <br /> BTEX compounds were detected in ground water samples collected from wells MW-1, MW-2, <br /> MW-3, MW-6 and MW-7 at concentrations as high as 12,000 yg/l (benzene, MW-1) <br /> . MTBE was detected in ground water samples collected from wells MW-1,MW-6,MW-7 and MW-8 <br /> at concentrations as Pugh as 580 µg11, DIPE was detected in a water sample collected from MW-1 <br /> at a concentration of 11 ,ugll No other fuel oxygenated additives were detected above laboratory <br /> reporting limits from the analyzed samples <br /> Previous and current analytical results of ground water monitoring well samples are summarized in <br /> Tables 2 and 3 The laboratory reports (Castle Analytical Laboratories Reference No 3355 and <br /> McCampbell Analytical Inc Lab ID 55271 through 55279)and chain-of-custody forms are presented <br /> in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The implications from the findings of the December 2000 investigation are <br /> • Groundwater monitoring data collected in the area of wells MW-1 through MW-10 indicated <br /> a ground water flow direction generally toward the northeast at a gradient of 0 004 ft/ft This <br /> appears to be the prevailing flow direction for the area Due to the low hydraulic gradient at <br /> the site, slight variations in ground water measurements or changes of recharge/discharge of <br /> the local ground water could greatly modify ground water flow direction <br /> Monitoring wells MW-1 and MW-10B are "drowned", and yield samples representative of <br /> deeper ground water conditions Deeper ground water In the area of MW-1 (48 to 53 feet <br /> 49 bsg) Is impacted, but is not impacted In the down-gradient area of MW-10B (50 to 55 feet <br /> Advanced GeoEnvironmental,Inc <br />