ARCHIVED REPORTS_XR0005319 - Laserfiche WebLink

Home Browse Search

was not detected in soil depth of 30 feet or 35 feet bsg. TPH-d was sam les collected at a 11 p detected in soil samples collected from depths of 15,20 and 25 feet bsg at concentrations of 5,100 mg/kg, 13,000 mg/kg and 490 mg/kg, respectively. TPH-d was not detected in soil collected at depths of 30 feet bsg or below(Tables 1 and 2). • On 26 October 2001,a total of four soil probe borings(P 12A/B and P 13A/B)were advanced at the site to the south and near the former UST location.Probe borings were advanced in the area of the former USTs to collect depth-discrete water samples. TPH-d was detected in all four of the grab ground water samples at concentrations from 130 micrograms per liter(µg11) ' to 550 µg/1 (Table 2). ' On 28 and 29 October 2002, monitoring well MW-5 and six ozone sparge wells (OPS lA through OPS3B) were installed. A total of three soil samples were collected from MW-5 and analyzed for TPH-g, TPH-d, BTEX and fuel additives. None of the target compounds were detected in the soil samples analyzed. ' Between June 1996 and February 2003, 20 ground water monitoring and sampling:events were performed at the site to monitor dissolved petroleum hydrocarbon concentrations in ground water and to characterize ground water flow direction and gradient on the site (Table 3). ' During the most.recent sampling event: TPH-d was detected in ground water samples collected from wells MW-1 and MW-4 at concentrations of 20,000 µg11 and 93,000 µ.g11, '. respectively. TPH-g was detected in samples MW-1 and MW-4 at concentrations of 1,400 µg/1 and 6,700 µg11, respectively. In addition, the BTEX compounds ethylbenzene, toluene and total xylenes were detected in sample MW-4 at concentrations of 1.8 µg/1, 2.1 . ' µg11 and 8.4 µg/1, respectively. • Ground elevations have increased approximately 0.8 feet during the monitoring period. • The lateral extent of the dissolved petroleum hydrocarbon plume is delineated by the current t area bounded by wells MW-1 through MW-5 and soil borings. GROUND WATER DEPTH AND FLOW DIRECTION ' In February 2003, ground water depth was measured at approximately 24 feet below surface grade (bsg). Review of historical AGE depth to ground water measurements indicates that ground water ' depth near the site has fluctuated between approximately 15 and 20 feet bsg. Ground water flow direction at the site can vary seasonally; however, the overall regional flow direction is southwest. i ' Advanced GeoEnvironmental,Inc.