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Site Background Information : Stallworth Auto Sales
<br /> Page 7 of 11
<br /> and 30 feet), and one soil sample from MW7 (70 feet) ; maximum concentrations
<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 (Ng/1), 90 , 000 pg/I and 3 , 300 pg/l , respectively. TPH-d was
<br /> detected in samples CPT7-75 , CPT8-70 , and B6-75 at concentrations of 4 , 800 pg/l , 8 ,400
<br /> pg/I and 5 ,600 pg/I , respectively. Two or more BTEX compounds were detected in samples
<br /> CPT7-75 , CPT8-70 , and B6-75 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/l , 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 MWA 1 , 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 MW 10 :
<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 /> Advanced GeoEnvironmental, Inc.
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