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10 January 2003 <br /> • AGE-NC Project No 96-0229 <br /> Page 4 of 5 <br /> summarized in Tables 3 and 4 The laboratory reports (Castle Analytical Laboratory reference no <br /> 4974) and chain-of-custody forms are presented in Appendix C <br /> 4 0. SUMMARY AND CONCLUSIONS <br /> IThe Implications from the findings of the August 2002 investigation are <br /> • Ground water flow direction in the area of wells MW-1 through MW-10 was inferred to be <br /> towards the northeast at an approximate gradient of 0 003 ft/ft This appears to be the <br /> prevailing flow direction for the area <br /> • Due to the low hydraulic gradient at the site, slight variations in ground water measurements <br /> or changes of recharge/discharge of the local ground water could greatly modify the inferred <br /> 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 /> lie <br /> bsg) is impacted by significant TPH-g, BTEX, 1,2-DCA and MTBE, deeper ground water <br /> In the area of downgradient well MW-10B is impacted by minor MTBE <br /> • Significant MTBE concentrations were detected in the sample collected from deep well <br /> MW-1 (screened48to 53 feet bsg),however only minor MTBE concentrations were detected <br /> in the samples collected from on-site water table wells,including MW-2(located only 5 feet <br /> from MW-1),implying that a deeper,vertically undelineated MTBE-impact may be present <br /> I (Figure 5) <br /> • The highest concentrations of dissolved MTBE were detected in off-site down-gradient well <br /> I MW-6, a trend of increasing off-site MTBE concentrations has generally been noted since <br /> March 2001 <br /> I • TPH-g, BTEX and MTBE were reported for the fifth consecutive quarter in water samples <br /> collected from MW-9, suggesting that the plume of petroleum-Impacted ground water may <br /> have shifted towards the east <br /> • Increasing MTBE concentrations have been reported from MW-l0A since at least March <br /> 2001, suggesting that the plume of MTBE-impacted ground water is migrating towards the <br /> northeast and beyond well MW-l0A <br /> • The elevated concentrations of petroleum hydrocarbons detected in samples collected from <br /> wells MW-1, MW-2, MW-3, MW-6 and MW-7 indicate that these wells are within or near <br /> the dissolved petroleum hydrocarbon"core area"of the plume (Figure 4) <br /> • <br /> IAdvanced GeoEnvironmental,Inc <br /> I <br />