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r..-Urq^,`. y�r_^s...�,... -. _ -+ " - v..rw-.� >,. A-' - ,^_ - �. - ..w ..;�.,. .a_ . ,. _ _�•�,-�...-.: -.., ,k �._ .. -..',s n - w-- -__ aF ^,r,, 26 July 2005 AGE-NC Project No 96=0235' " 1, I ' Page 4 of S 1 t 4.0. SUMMARY AND CONCLUSIONS f Based on the,data collected from the former UST areas, AGE finds i a^ ` y ' •. The shallow-screened data Infer a net flow towards the west at a gradient of 0 025 ft/ft or I h, south at the UST #3 area , the intermediate-screened data delineated a ground water flow , ' a direction toward the west at a gradient of 0 01 ft/ft Ground water gradient and flow direction in the shallow-screened water wells observed during the second quarter 2005 was similar to the previous quarter,yet flow direction observed from the intermediate-screened water wells ' was opposite of the normal flow direction in the former UST cluster area= 1 • ITPH-g and TPH-d were detected only in the samples collected from MW-1 and MW-2 at maximum concentrations of21,000[tg/l'and 6,500[g/1;respectively BTEX compounds also r 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 well MW-9 at concentrations as high as 34 µg/1 (MW-9) 1,2-DCA and'TAME also were detected,in ground water samples collected from wells MW-1,MW-2 r The most-impacted ground water appears to be centered around the dispenser area of the s farmer 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' ' or low table level (MW-1,and MW-2) The vertical extent of the contamination plume, as : r well as the lateral extent to the south,is not well defined and requires additional monitoring points _ . � h 5.0. RECOMMENDATION5 1 Based on the findings of the environmental activities recounted in this report, AGE recommends • Continued limited quarterly ground water monitoring," , • Performance of interim remediation of,shallow hydrocarbon impacted ground water at the ' UST Cluster area, and I ' ' ' I , 11 f �s t { Advanced Geo>nvironmental,Inc ,n A , a , i 1