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I13 August 2003 <br /> AGE-NC Project 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 0 003 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 340 micrograms per <br /> liter (gg/1) The laboratory indicated that the sample chromatogram from MW-2 had significant <br /> unmodified or weakly modified gasoline <br /> BTEX compounds were detected from the same well at concentrations as high as 27 µg/1(benzene) <br /> MTBE was detected8260 EPA les collected from wells MW-1 MW-2 and <br /> ( ) in ground water samples <br /> MW-3 at concentrations of between 5 9µg/l(MW-1)and 9,200µg/l(MW-2) No other constituents <br /> of concern were detected above laboratory reporting limits in the analyzed samples Previous and <br /> current analytical results of ground water monitoring well samples are summarized In Tables 3 and 4 <br /> • The laboratory reports (McCampbell Analytical Inc Lab I D No 0303039) and chain-of-custody <br /> forms are presented in Appendix B <br /> 4.0. SUMMARY AND CONCLUSIONS <br />' The implications from the findings of the March 2003 investigation are <br /> • The depth to ground water at the site was approximately 53 feet below surface grade, or <br /> approximately 14 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 0 003 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 March 2003, TPH-g concentrations have fluctuated from MW-2 <br /> between 140 µg/1 and 8,900 µgll <br /> • BTEX constituents were detected in the water sample collected from MW-2 Benzene <br /> concentrations were above the DHS's Maximum Contaminant Level (MCL) of 1 0 µg/l In <br /> . drinking water <br />' Advanced GeoEnvironmental,Inc <br /> I <br />