ARCHIVED REPORTS_XR0006950 - Laserfiche WebLink

Home Browse Search

' 12 December 2005 AGE-NC Project No 97-0333 Page 9 of 11 µ decreasing trend The results from the ground water monitoring and sampling event performed between 05 & 06 July ' 2005 are as follows • Generally,depth to ground water at the site varied between 18 and 23 feet bsg,ground water ' elevations ranged between 9 22 feet(MW-11F)and 13 34feet(MW-10A)above MSL The ground water elevation decreased approximately 3 33 feet between the March 2005 and the July 2005 ground water monitoring events,the decrease in elevation may be due to seasonal ' fluctuation • First Zone ground water flow was inferred to be toward a ground water depression in the area ' of wells EW-1, MW-6, and MW-7A under a hydraulic gradient of approximately 0 012 ft/ft from the east and west On the south-half of the site,ground water was inferred to be oriented toward the ground water depression under a gradient of approximately 0 008 ft/ft, off-site ' towards the north near well MW-12, ground water was inferred to be oriented towards the ground water depression at a gradient of approximately 0 003 ft/ft (Figure 4) to • Second Zone,Third Zone,and Primary Aquifer ground water flow was inferred to be toward the northwest at approximate gradients of 0 002 ft/ft or less (Figures 5, 6, and 7, respectively) • Due to the low ground water gradient at the site, small variations in ground water measurements or changes of recharge/discharge of the local ground water could greatly modify the inferred ground water flow direction ' • Historically,the highest on-site concentrations of dissolved MTBE have been detected in the samples collected in the area of First Zone monitoring wells MW-2, MW-3, MW-6 and MW-7A During the second quarter 2005, the highest MTBE concentration was detected from well MW-3 at 69,000 µg/l Furthermore, a significant MTBE increase(approximately one order of magnitude) was reported from wells MW-2, MW-3, MW-6 and MW-7A 1 Historically,the highest on-site concentrations of dissolved TAME have been detected in the samples collected in the area of First Zone monitoring wells MW-2, MW-3, MW-6 and MW-7A During the second quarter 2005, the highest TAME concentration was detected from well MW-3 at 3,700 µg11 Furthermore, a significant TAME increase (approximately one order of magnitude) was reported from wells MW-2, MW-3 and MW-6 • Historically,the highest on-site concentrations of dissolved 1,2-DCA have been detected in the samples collected in the area of monitoring wells MW-7(B-E)and MW-8(B-D) During the second quarter 2005, the highest 1,2-DCA concentration was detected from First Zone well MW-6 at 140 µg11 Furthermore, significant and first time detections of 1,2-DCA were reported from First Zone wells MW-2, MW-3, MW-6 and MW-7A Advanced GeoEnvironmental,Inc