WORK PLANS - Laserfiche WebLink

Home Browse Search

19 December 2003 AGE-NC Project No. 95-0135 Page 2 of 7 Based on data collected from the site in April 2003,the average depth to ground water at the site is approximately 61 feet below surface grade(bsg).The ground water in April 2003 was inferred to be flowing toward the east-northeast under a gradient of 0.0007 ft/ft. 2.2. UNDERGROUND STORAGE TANK REMOVAL Two 5,000-gallon USTs (Nos. 1 and 2), one 12,000-gallon UST (No. 3), and one 500-gallon UST (No. 4), associated dispensers and product piping were removed from the site on 13 January 1999. The USTs were removed from three separate excavations located near the repair facility(Figure 2). Upon removal of the USTs,soil samples were collected from the floors of the excavations at depths between 8 feet and 14 feet below surface grade (bsg). Total petroleum hydrocarbons quantified as gasoline (TPH-g) were detected at concentrations as high as 29,800 milligrams per kilogram (mg/kg); volatile aromatics (benzene, toluene, ethylbenzene and xylenes: BTEX)were detected at concentrations as high as 2,490 mg/kg; and methyl tertiary butyl ether (MTBE) was detected at concentrations as high as 9.1 mg/kg. Trichloroethene was also detected in a soil sample collected beneath UST (No. 4) at a concentrations of 220 mg/kg. Analytical results of the soil samples collected during January 1999 are displayed in Table 1. 2.3. PREVIOUS SITE ASSESSMENT AND SAMPLING On 10 and 11 June 1999,AGE advanced five borings Bl, B2, B3, B4, and B5, to depths of 64, 55, 30,30,and 55 feet below surface grade(bsg),respectively. One of the five borings(B1/MW-1)was completed as a ground water monitoring well. TPH-g was detected in soil sample B1-40' at a concentration of 1.6 mg/kg. Additionally, BTEX compounds were detected in sample 131-40' at concentrations as high as 0.20 mg/kg. The fuel oxygenate MTBE was detected at concentrations of 3,400 micrograms per kilogram(ug/kg)and 67 ug/kg in samples B 1-30'and 132-30',respectively.TPH-d and TPH-mo were not detected in the soil samples analyzed. A total of three grab ground water samples were submitted for analysis. TPH-g was detected in the ground water sample collected from boring B1, at a concentration of 2,400 micrograms per liter (ug/1). TPH-g was not detected in the grab ground water samples B2-W and 135-W collected from borings B2 and B5. BTEX compounds were detected in grab ground water samples collected from B 1 and B2 at concentrations as high as 170 ug/1 and 1.7 ug/l,respectively. BTEX compounds were not detected in sample B5-W. Advanced GeoEnvironmental,Inc.