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1 ' 02 February 2004 • AGE-NC Project No 99-0624 Page 7of8 ' analyzed samples Previous and current analytical results of ground water monitoring well samples are summarized in Tables 5 and 6 The laboratory report(CAL Reference No 612 1) and chain-of- custody forms are presented in Appendix G 1 4.0 SUMMARY AND CONCLUSIONS The following conclusions were drawn from the results of this investigation • Generally, silty sand and fine sand were encountered in boring MW-6, gray to brown silt ' with sand was encountered at 30 feet and 70 feet bsg, and gray to reddish brown silty sand and poorly graded fine sand were recovered at all other sampling depths in boring MW-7 ' Stratigraphic cross sections are depicted in Figures 3 and 4 • MTBE was detected by EPA method 8260 in the soil sample collected from 50 feet, 70 feet, ' 80 feet and 90 feet bsg in boring MW-7 at concentrations of 28 mg/kg, 2 1 mg/kg, 0 022 mg/kg and 0 086 mg/kg,respectively The vertical extent of MTBE-impacted soil has not been defined and may possibly extend beyond 90 feet bsg Cross sections illustrating the lie extent of impacted soil are depicted in Figures 5 and 6 • The lateral extent of MTBE-impacted soil has been defined in every direction, except ' towards the south beyond well MW-3 • The depth to ground water at the site was approximately 54-55 feet below surface grade, or approximately 13 30 feet below mean sea level ' 0 Ground water flow direction in the area of wells MW-1 through MW-4 and MW-6 was Inferred to be towards the south-southwest 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 ' 0 TPH-g was detected at 51 µg/1,dust above laboratory reporting limits,In the sample collected from well MW-1 This is the first detection of TPH-g in the previous five quarters ' 0 TPH-g was detected in the ground water sample collected from well MW-2 at a concentration of 2,800µg/1,between November 1999 and June 2003,TPH-g concentrations have fluctuated from 140 µg/1 to as high as 23,000 gg/l in samples from well MW-2 ' BTEX constituents were detected in the water sample collected from MW-2 and the Initial water sample(24 July 2003) from well MW-7 The benzene concentration in sample MW-2 ' was above the DHS's Maximum Contaminant Level (MCL) of 1 0 µg/1 in drinking water IAdvanced GeoEnvironmental,Inc t 1 '