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<br /> 26 April 2011
<br /> AGE-NC Project No. 95-0104 'f
<br /> Page 9 of 12 ;¢
<br /> Prior to SVE remediation, hydrocarbon impacted-soil was late rally defined by B-1, MW-1,
<br /> MW-2, MW-5, and MW-6; hydrocarbon impacted-soil ways vertically defined in the source
<br /> area, by soil samples collected from soil boring VW-1.The only soil samples collected from
<br /> the site that have been analyzed for 1,2-DCA were collected from probe boring P-1 in July
<br /> 2000. Analysis of those soil samples indicated that there is 'iso 1,2-DCA impacted soil
<br /> beneath the site (Table 2). Furthermore, TPH-g and BT EX compounds were not detected
<br /> in soil samples collected from confirmation boring P�1.1, indicating that hydrocarbon
<br /> impacted soil does not extend beyond the limits of the former UST area since SVE
<br /> remediation was performed.
<br /> GROUND WATER IMPACT t
<br /> Total petroleum hydrocarbons as gasoline and diesel ,(TPH-g and TPH-d), benzene,
<br /> toluene, ethylbenzene and xylenes (BTEX) have not been ',detected in ground water
<br /> samples collected from the site since June 2001. 1� r� - » �
<br /> From January 1995 to March 1997, dissolved 1,2-DCA concentrations at the site were as
<br /> high as 540 pgll (MW-1). 1,2-DCA was not analyzed in the ground water samples collected
<br /> from the site between March 1997 and June 2001. Analysis of ground water samples for
<br /> 1,2-DCA resumed in June 2001 (Table 3). 1,2-DCA concentrations have been declining
<br /> since the initiation of quarterly.ground water monitoring. After resuming sampling, the
<br /> highest concentrations of dissolved 1,2-DCA was detected in well MW-5 during the June
<br /> 2001 event at 160 pg/l. However, 1,2-DCA concentrations ;lin ground water samples
<br /> collected from MW-5 had decreased to 77 pgll in January 2002, and 42 pg/l in June 2002.
<br /> Between 2003 and 2006, 1,2-DCA concentrations in ground water samples collected from
<br /> MW-5 ranged from 5.2 pgll to 18 pg/l. ii .
<br /> Since 2006, concentrations of 1,2-DCA have not been detected;above laboratory reporting
<br /> limits in ground water samples collected from shallow-screened wells MW-1, MW-10,
<br /> MW-11, MW-12, and VW-1, and deep-screened wells MW-2, MW-3, and MW-4.
<br /> Additionally since 2006, 1,2-DCA was only detected d'uring?three sampling events in
<br /> samples collected from down-gradient deep-screened well MW-9 and shallow-screened
<br /> well MW-6, at concentrations ranging between 3.0 pgll (February 2009) and 6.3 pgll
<br /> (August 2007). Between June 2006 and August 2009, 1,2-D4 was detected in samples
<br /> collected from wells MW-5, MW-7, and MW-8 at concentrations between 2.5 pgll and
<br /> 28 pg/l. Between April 2008 and August 2010, 1,2-DCA was detected in samples collected
<br /> from wells MW-13 and MW-14 at concentrations between 6.1 pgll and 34 pg/l. 1,2-DCA
<br /> concentrations were not detected above laboratory reporting limits in ground water
<br /> sampled collected from the site during the last sampling event performed in August 2010.
<br /> Advanced GeoEnvironmental,Inc.
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