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11 September 2003 <br /> • AGE-NC Protect No 99-0624 <br />�. Page 3 of 5 <br /> The general ground water gradient in the area of wells MW-1 through MW-4 was calculated to be <br /> approximately 0 002 ft/ft or less, or approximately 16 feet per mile and inferred to be flowing <br /> towards the south <br /> 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> A total of four ground water samples were submitted to a DHS-certified laboratory TPH-g was <br /> detected in the water sample collected from well MW-2 at a concentration of 23,000 micrograms per <br />' liter (µg/1) The laboratory indicated that the sample chromatogram from MW-2 had significant <br /> unmodified or weakly modified gasoline BTEX compounds were detected from the same well at <br /> concentrations as high as 13 µg/l (benzene) <br />' MTBE was detected (EPA 8260) in ground water samples collected from wells MW-1, MW-2 and <br /> MW-3 at concentrations of between 34 µg/l(MW-4) and 19,000 µg/l(MW-2) Tame was detected <br /> (EPA 8260) in ground water samples collected from MW-2 at concentrations of 130 µg/1 No other <br /> constituents of concern were detected above laboratory reporting limits in the analyzed samples <br /> Previous and current analytical results of ground water monitoring well samples are summarized in <br />' . Tables 3 and 4 The laboratory reports (McCampbell Analytical Inc Lab I D No 0303039) and <br /> chain-of-custody forms are presented in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The implications from the findings of the June 2003 investigation are <br /> • The depth to ground water at the site was approximately 52-53 feet below surface grade, or <br /> Iapproximately 13 80 feet below mean sea level <br /> • Ground water flow direction in the area of wells MW-1 through MW-4 was inferred to be <br />' towards the south-southwest at an approximate gradient of 0 002 ft/ft Due to the low <br /> hydraulic gradient at the site, slight variations in ground water measurements or changes of <br /> recharge/discharge of the local ground water could greatly modify the inferred ground water <br />' flow direction <br /> • TPH-g was detected in the ground water sample collected from well MW-2, between <br /> November 1999 and June 2003,TPH-g concentrations have fluctuated from MW-2 between <br />' 140 µg/1 and 23,000 µg/1 <br /> • BTEX constituents were detected in the water sample collected from MW-2 Benzene <br /> I concentrations were above the DHS's Maximum Contaminant Level (MCL) of 10 go In <br /> drinking water <br /> Advanced GeoEnvironmentat,Inc <br />