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' 10 January 2005 AGE-NC Project No 95-0184 ' Page 4of5 4.0. SUMMARY AND CONCLUSIONS Based upon data collected from the site, AGE concludes the following ' • Ground water elevations at the site averaged approximately 24 68 feet below MSL All ground water wells except VW-3,VW-4, and VW-5B were"drowned",with water levels as ' high as 17 feet above the screened intervals of the drowned wells (MW-1) • The ground water was inferred to flow generally northeast across much of the site at a gradient of approximately 0 004 ft/ft This ground water flow direction is consistent with the last 23 of 24 monitoring events (Table 4) • Detectable concentrations of TPH-g were found in all of the ground water wells sampled Generally,concentrations remained stable s omp�ed to the previous quarter One or more BTEX compounds were found in all groun water samples collected These samples contained one or more analytes at concentrations above the DHS' Maximum Contaminant Levels (MCL) for drinking water VW-1 • MTBE was detected in samples from wellsAMW-4, VW-2B, and VW-4 at concentrations ranging from 140 lig/l(MW-4)to 300 gg/l(VW-4) 1,2-DCA was detected in MW-2,MW-4, VW-2B, VW- VW-4, V -5B, and VW-5C at concentrations ranging from 5 7 µg/1 (MW-2) to �ig/1 (VW-- EDB was detected in MW-4, VW-2B, VW-5B, and VW-5C at concentrations ranging from 35 µg/1 (VW-5C) to 220 gg/l (VW-2B) The concentrations of MTBE, 1,2-DCA, and EDB in the ground water samples exceed their respective MCLs for drinking water • Naphthalene, 1,2,4-tnmethylbenzene, 1,3,5-tnmethylbenzene, and n-propylbenzene were detected in ground water samples at concentrations above the DHS-recommended dunking ' water Action Levels • The vertical and lateral extent of impacted soil and ground water has not yet been defined The concentration of dissolved constituents collected in samples from deeper monitonng wells have been documented to be lower than the shallow, vapor well samples Therefore, the maximum concentration of the release appears to reside in the upper 50 feet of the ' subsurface 5.0. RECOMMENDATIONS Based upon data collected from the site, AGE recommends continued quarterly ground water monitoring AGE is currently preparing a work plan to further delineate the vertical and lateral extent of impacted ground water on-and off-site,as requested in the EHD in a letter dated 31 August 2004 Advanced GeoEnvironmental,Inc r