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I10 August 2005 <br /> i AGE-NC Project No 99-0559 <br /> IPage 6 of 8 <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Based on data collected during the monitoring event, AGE concludes <br /> • The general ground water flow direction was towards north and northwest in the first <br /> encountered water table and generally towards the southwest in the lower hydrogeologic <br /> units during the fourth quarter While the lowest hydrogeologic unit HU6 exhibited a <br /> northeasterly flow direction <br />' 0 The significant magnitude of the TPH-g detections were in the shallow wells near the former <br /> UST release The highest concentrations of petroleum hydrocarbons detected this quarter at <br /> the site were present in the ground water samples collected from wells screened in HU1 and <br /> HU2 at the east edge of the UST area <br /> • BTEX concentrations increased in well MW-1,remained stable in well MW-2 and remained <br /> stable or decreased in wells MW-3 and MW-4 BTEX concentrations also increased in the <br /> upper screen intervals of wells MW-5 and remained stable well MW-6 MTBE was detected <br /> at significant concentrations in wells MW-2,MW-3 and MW-4,MW-6A and MW-7A,with <br /> lower concentrations detected in wells MW-1 and the remaining well screens with MTBE <br /> impacted ground water detected the depth of 180 feet bsg in well MW-7 The core of the <br /> MTBE plume is situated over the former UST areas (MW-7A, MW-2 and MW-4) and <br /> extends south to well MW-6A and southwest to well MW-5A <br /> • 1,2-DCA was detected in two samples collected from the former UST release at the site <br /> Other fuel additives were also detected near the former UST area <br /> • The vertical extent of impacted ground water,has been defined at the perimeter of the site, <br /> the vertical extent of impacted ground water at the western and southern edge of the site are <br /> I defined by well MW-5, and to a lesser degree by MW-6 The vertical extent of impacted <br /> ground water,at the former UST area,has not been defined and extends beyond the vertical <br /> depth of well MW-7E <br /> • The lateral extent of shallow, impacted ground water towards the west and southwest, <br /> down-gradient of the UST area, has not been defined <br /> 5.0. RECOMMENDATIONS <br /> Based on the re findings and conclusions in this ort, AGE recommends the following <br /> p <br /> • Continued quarterly ground water monitoring, the next quarterly monitoring event was <br /> performed in June 2005 <br /> Advanced Geoh,nvironmeatal,Inc <br />