ARCHIVED REPORTS_XR0008717 - Laserfiche WebLink

Home Browse Search

06 January 2006 AGE-NC Project No 99-0559 Page 4 of 7 peziometric depression located in the vicinity of the former UST area(Figure 3)at a gradient varying from 0 016 ft/ft to 0 07 ft/ft HU3 and HU4 In the wells representing HU3 and HU4, the depth to ground water ranged from 55 96 to 58 49 feet btoc The ground water elevation was calculated at between 29 77 feet(MW-7B) and 31 11 feet (MW-5B)below MSL,the ground water elevation from wells in this hydrogeologic interval averaged 30 55 feet below MSL, a decrease of 1 foot since the last quarterly monitoring event Ground water was inferred to be flowing south-southwest at a gradient of 0 009 ft/ft (Figure 4) HU5 Within the upper portion of HU5 (Upper HU5), screened between 125 and 135 feet bsg, ground water elevation ranged between 29 90 feet(MW-7C)and 30 92 feet(MW-5C)below MSL, the ground water elevation averaged 30 40 feet below MSL, a decrease of 0 4 feet since the last monitoring event Ground water at the former UST release was inferred to be flowing toward the west-southwest at a gradient of 0 005 ft/ft (Figure 5) Within the lower portion of HUS (Lower HU5), screened between 148 and 160 feet bsg, ground water elevation ranged between 29 86 feet (MW-7D) and 30 94 feet (MW-6D) below MSL, the ground water elevation averaged 30 57 feet below MSL, a decrease of 0 08 feet since the last monitoring event Ground water was determined to be flowing toward the south-southeast at a hydraulic gradient of 0 011 ft/ft (Figure 6) HU6 In the wells representing HU6,the depth to ground water ranged between 56 09 and 56 98 feet btoc The ground water elevation was calculated between 31 49 feet (MW-5E) and 3167 feet (MW-7E) below MSL, the ground water elevation from wells in this hydrogeologic unit averaged 31 59 feet below MSL, an increase of 0 28 feet since the last quarterly monitoring event Ground water was inferred to be flowing toward the east at a hydraulic gradient of 0 002 ft/ft (Figure 7) 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLE ANALYSIS Ground water samples were analyzed by CTEL for the chemical constituents referenced in Section 2 2 The following is a summary of the analytical results HU1 and HU2 TPH-g was detected in wells MW-1 through MW-4 and wells MW-5A through MW-7A at concentrations ranging from 12,00 micrograms per liter (µg/1) in the ground water samples from wells MW-5A and MW-6A to 4,300,000 µg/1 in the sample from well MW-2 BTEX compounds were detected at maximum concentrations of 220,000 µg/1 benzene, 800,000 µg/1 toluene, 330,000 µg/1 ethyl-benzene and 1,350,000 µg/l total xylenes in sample MW-2 In addition, the following fuel additives were detected MTBE was detected in all samples at concentrations Advanced GeoEnvironmental,Inc