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Site Background Information: Stallworth Auto Sales
<br /> Page 7 of 11
<br /> were 0.024 mg/kg benzene (MW7-70), 270 mg/kg toluene (VW1-30), 220 mg/kg
<br /> ethylbenzene (VW1-20), and 950 mg/kg xylenes (VW3-20).
<br /> On 17 July 2007, an 8-hour pilot test was conducted using lower vadose-screened vapor
<br /> well VW-1, screened from 20 feet to 30 feet bsg, as the extraction well. On 18 July 2007,
<br /> an 8-hour pilot test was conducted using upper vadose-screened vapor well VW-2,
<br /> screened from 10 feet to 20 feet bsg, as the extraction well. Based upon a vacuum of 0.1
<br /> inches of water, the projected radius of influence (ROI) of lower and upper vadose SVE at
<br /> the site will be approximately 24 feet. TPH-g was detected at a maximum concentration of
<br /> 90,000 pg/I in vapor during the lower vadose SVE pilot test.
<br /> On 05, 06 and 07 February 2008, cone penetration testing and grab ground water sampling
<br /> was conducted on-site and off-site (521 East Oak Street) utilizing a 25-ton truck-mounted
<br /> CPT drill rig. Ten grab ground water samples were collected from borings CPT-6, CPT-7,
<br /> CPT-8, B-5 and B-6 from two water bearing zones (67 to 75 feet bsg and 124 to 130 feet
<br /> bsg). TPH-g was detected in samples CPT7-75, CPT8-70, and 136-75 at concentrations of
<br /> 1 ,800 micrograms per liter (pg/1), 90,000 pg/I and 3,300 pg/I, respectively. TPH-d was
<br /> detected in samples CPT7-75, CPT8-70, and 136-75 at concentrations of 4,800 pg/I, 8,400
<br /> pg/I and 5,600 pg/l, respectively. Two or more BTEX compounds were detected in samples
<br /> CPT7-75, CPT8-70, and 136-75 at maximum concentrations of 3,300 pg/I benzene, 4,200
<br /> pg/I toluene, 3,000 pg/I ethylbenzene, and 13,100 pg/I total xylenes in sample CPT8-70.
<br /> TAME and 1,2-DCA were detected in sample CPT8-70 at concentrations of 290 pg/I and
<br /> 82 pg/I, respectively. Chemicals of concern (COC) were not detected in any grab ground
<br /> water samples collected within the 124 to 130 feet bsg water bearing zone.
<br /> Based upon the above analytical results of grab ground water samples collected during the
<br /> CPT investigation, on 13 and 14 March 2008, two ground water monitoring wells, MW-9
<br /> and MW-11, were installed on-site and one ground water monitoring well, MW-10, was
<br /> installed off-site at 521 East Oak Street. COC were not detected at or below detection
<br /> limits in the soil samples analyzed from boring MW9.
<br /> The following COC were detected in the soil samples collected from boring MW10:
<br /> • TPH-g was detected in soil samples collected from MW 10 at depths of 60 feet and
<br /> 70 feet bsg at concentrations of 13 milligrams per kilogram (mg/kg) and 1.2 mg/kg,
<br /> respectively.
<br /> • BTEX compounds were detected at a depth of 70 feet bsg at concentrations of
<br /> 0.010 mg/kg benzene, 0.028 mg/kg toluene, 0.010 mg/kg ethylbenzene and 0.060
<br /> mg/kg total xylenes.
<br /> The following COC were detected in the soil samples collected from boring MW11:
<br /> Advanced GeoEnvironmental,Inc.
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