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` , R fr ' 20 April 2005 . AGE-NC Project No 96-0235 f ;, ' Page 4 of 5 f 4.0. SUMMARY AND CONCLUSIONS Based on the data collected from the forme_r UST areas, AGE finds ' The shallow-screened data infer a net flow towards the west to southwest at a gradient of 0 003 ft/ft or southeast at the UST #3 area , the intermediate-screened data delineated a ' ground water flow direction toward the south to southwest at a gradient of 0 005 ft/ft to 0 008 ft/ft Ground water gradient and flow direction in the intermediate-screened water wells observed during the first quarter 2005 was similar to the previous quarter,yet flow direction ' observed from the shallow-screened water wells was opposite of the normal flow direction • TPH-g and TPH-d were detected only in the samples collected from MW-1 and MW-2 at maximum concentrations of 15,000 µg11 and 5,400 µg11, respectively Various BTEX ` ' compounds also were detected in the MW-1 and MW-2 samples • The fuel additive MTBE was- detected in the shallow-screened well MW-10 and the intermediate-screened wells MW-9,MW-11B, MW-12B, MW-13B and MW-14B at concentrations as high as 49 gg/l (MW-9) '1,2-DCA also was detected, in ground water samples collected from wells MW-1,'MW-2 and MW-14B • The most-impacted ground water appears to be centered around the dispenser area of the former UST cluster,based on previous contaminant detections in former well EW-1,located at the southern edge of the former dispenser island The vertical extent of the contamination plume, as well as the lateral extent at the former UST cluster, was generally defined by ' previous CPT soil boring samples • Based on non-detectable contaminant concentrations in shallow monitoring wells since March 2001,the dissolved plume release from the former UST#3 area appear to be isolated , below the current water table and resides at a depth associated with a historical smear zone a or low table level (MW-1 and MW-2) The vertical extent of the contamination plume, as well as the lateral extent to the south, is not well defined and requires additional monitoring' points r i 5.0. RECOMMENDATIONS i Based on the findings of the environmental activities recounted in this report, AGE recommends i • Continued limited quarterly groundwater monitoring, • Performance of interim remediation of sliallow hydrocarbon impacted ground water at the UST Cluster area, and , ' Advanced GeoEnvtronmental,Inc r