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' 30 July 2002 AGE-NC Project No 99-0624 ' Page 3 of 5 depicted and contoured in Figure 3 The general ground water gradient in the area of wells MW-1 through MW-4 was calculated to be approximately 0 002 ft/ft or less, or approximately 11 feet per mile and inferred to be flowing towards the south-southwest ' 3 2 LABORATORY RESULTS OF GROUND WATER SAMPLES A total of three ground water samples were submitted to a DHS-certified laboratory TPH-g was ' detected in water samples collected from wells MW-2 and MW-3 at concentrations of 800 micrograms per liter (ug/1) and 61 ug1l, respectively The laboratory indicated that the sample ' chromatograms from MW-2 and MW-3 had significant unmodified or weakly modified gasoline BTEX constituents were detected in ground water samples collected from wells MW-2 and MW-3 tat concentrations ranging as high as 79 pg/1 (xylene, MW-2) . MTBE was detected (EPA 8260) in ground water samples collected from wells MW-1,MW-2 and ' MW-3 at concentrations ranging as high as 11,000 pg/1 (MW-2) No other constituents of concern were detected above laboratory reporting limits in the analyzed samples Previous and current analytical results of ground water monitoring well samples are summarized in Tables 3 and 4 The ' laboratory reports (McCampbell Analytical Inc Lab I D No 0203200-1, 2 and 3) and chain-of- custody forms are presented in Appendix B ' 4.0. SUMMARY AND CONCLUSIONS ' The implications from the findings of the March 2002 investigation are • The average depth to ground water and ground water elevation on-10 March 2002 in monitoring wells on-site was approximately 50 feet below surface grade and 11 feet below MSL, respectively • Ground water flow direction 1n the area of wells MW-1 through MW-4 was inferred to be towards the south-southeast at an approximate gradient of 0 002 ft/ft Due to the low hydraulic gradient at the site, slight variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction I • TPH-g was detected in ground water samples from wells MW-2 and MW-3, the highest • concentration was detected in the sample collected from MW-2 at 800 µg/l,a steady increase Advanced GeoEnvironmental,Inc