ARCHIVED REPORTS_XR0009409 - Laserfiche WebLink

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1 ' SITE ASSESSMENT INVESTIGATIONS • ' On 24 June 1997, a total of nine soil probe borings(B 1 through 139)were advanced at the site under EHD oversight Soil in probe bonngs B I through B5 were continuously sampled (cored), whereas soil in probe boring B6 was sampled at the vadose zone/ground water interface In addition, grab ' ground water samples were collected from BI through B9 The grab ground water samples and selected soil samples were analyzed for TPH-g,TPH-d,BTEX and methyl tert-butyl ether(MTBE), however, soil samples collected from probe boring B1 were not analyzed, because field screening ' with a organic vapor monitor (OVM) indicated that the samples were not impacted by petroleum hydrocarbons ' • TPH-g was detected in six soil samples collected from four of the probe bonngs,B2,B3,B4 and B5 TPH-g was detected at concentrations as high as 5,000 mg/kg (B5-6') at depths of 8 feet bsg or less TPH-g concentrations detected in soil from depths greater than 8 feet bsg ' were as high as 550 mg/kg(B4-9') TPH-g was not detected at depths of 12 to 16 feet in the area of the former USTs,nor was TPH-g detected in the soil sample collected from B6 Total petroleum hydrocarbons quantified as diesel (TPH-d) was detected in the soil sample ' collected from probe boring B2 at a depth of 8 feet bsg at a concentration of 510 mg/kg • BTEX compounds were detected in soil samples collected from depths of less than 8 feet bsg ' at concentrations ranging from 0 007 (ethyl benzene, B6-8') to 480 mg/kg (xylene, B5-6') BTEX compounds were also detected at a depth of 12 feet bsg in borings B2,B3 and B5 No petroleum hydrocarbons or BTEX compounds were detected in the soil sample collected �• from a depth of 16 feet bsg in the former UST area • TPH-g was detected in each of the eight grab ground water samples collected from the site I at concentrations ranging from 220 micrograms per liter(µg/1)to 240,000 µg/1 TPH-d was detected in both of the grab ground water samples at concentrations of 44,000 µg11 and 310,000 µg/l BTEX compounds were detected in each of the water samples analyzed at I concentrations ranging from 0 56 µg/1 benzene in boring B1 to 20,000 µg/1 of benzene in boring B7 MTBE was also detected at concentrations up to 1,000 gg/1 by EPA Method 8020 However, the highest concentration of MTBE detected by EPA Method 8260 was ' 180 µg/1 On 12 and 13 February 1998 five ground water monitoring wells were installed on-site and off-site of the subject property Soil borings B10 and B14 were completed as dual-screened ground water monitoring wells MW-2 and MW-1, respectively Soil bonngs B11, B12, and B13 were completed I as conventional ground water monitoring wells MW-3, MW-6 and MW-5, respectively • TPH-g was detected in samples collected from well MW-IA and MW-IB at concentrations of 220 and 2,000µg/1,respectively TPH-d was detected samples collected from well MW-1B at a concentration 160 µg/1 Benzene was detected in samples collected from wells MW-lA and MW-1B at concentrations of 15 µg/1 and 530 µg11,respectively Toluene,ethyl benzene and xylenes were also detected in MW-lA and MW-1B at concentration as high as 260 µg11 (toluene, MW-1B) MTBE was detected in the sample collected from well MW-lB at a . concentration 9 9 µg/1 I