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Remedial Action Plan June 14, 2017
<br /> Project#Z054000052 Page 4
<br /> (UST1 N-20.5, UST1 M-21.5, UST1 S-21, UST2N-20, UST2M-21.5, UST2S-21, UST3N-20, UST3S-20, UST3M-
<br /> 22, and UST3M-N-21), piping (P-1-15, P-1-35, P-1-55, and P-1-75), and dispensers (D1-10, D2-10, D3-10)
<br /> using direct-push or hollow-stem auger (HSA) methods (GHC, 2008a).
<br /> In preparation for pending site redevelopment activities, in October 2010, Stantec Consulting Corporation
<br /> (Stantec) destroyed wells MW-4, MW-10, MW-11R, VW-1, VW-3, VW-4 (A,B,C), VW-5 (A,B,C), and VW-6
<br /> (A,B,C) and protected wells MW-3, MW-7, and MW-12R in accordance with Stantec's Addendum to July 8,
<br /> 2010 Work Plan for Monitoring Well Destruction and Replacement, and Additional Path Forward, dated
<br /> September 23, 2010 (approved by the SJCEHD on October 1, 2010). Well destruction and protection activities
<br /> are documented in Stantec's Well Destruction and Well Protection Report, dated March 15, 2011.
<br /> In May 2011, ATC supervised the recovery of previously protected wells MW-3, MW-7, and MW-12R, and the
<br /> installation of monitoring wells MW-4R and MW-13 through MW-16. The work was performed in accordance
<br /> with ATC's Letter Addendum to Stantec's `Addendum to July 8, 2010 Work Plan for Monitoring Well
<br /> Destruction and Replacement, and Additional Path Forward, dated April 13, 2011. Results of the well
<br /> installation activities are documented in ATC's Monitoring Well Installation Report, dated July 22, 2011.
<br /> In February 2012, ATC supervised the installation of on-site groundwater monitoring wells MW-17 and MW-19
<br /> through MW-22, vertical delineation soil boring SB-1, and the collection of shallow soil vapor samples SV-1
<br /> through SV-5. The results of the site assessment activities were presented in Cardno ATC's Additional Site
<br /> Assessment Report, dated July 30, 2013.
<br /> On October 15 and 16, 2014, Cardno ATC (now ATC) supervised the installation of three soil vapor wells
<br /> (SVE-1 through SVE-3) and one air sparge well (AS-1) at the site. The work was performed in accordance with
<br /> Cardno ATCs Workplan For An Air Sparge/Vapor Extraction Pilot Test, dated July 11, 2014. On January 5
<br /> through 7, 2015, Cardno ATC conducted the pilot test described in the above workplan. The results of the
<br /> sampling conducted during the well installation and the results of the pilot test Results were summarized in
<br /> Cardno ATC's Pilot Test Summary Report dated August 4, 2015.
<br /> On January 13, 2015 Cardno ATC supervised the installation of monitoring well MW-23 into the deep water
<br /> bearing zone to 60 feet bgs. No hydrocarbons were detected in soil samples collected. The work was
<br /> performed in accordance with Cardno ATCs Workplan For Additional Soil And Groundwater Assessment,
<br /> dated August 12, 2014.
<br /> Well construction details are summarized on Table 1.
<br /> 2.3 SITE REMEDIATION
<br /> On September 14, 1995, on behalf of Thrifty, Alton Geoscience (Alton) performed a soil vapor extraction (SVE)
<br /> test at the site to assess the possibility of using this technology for soil remediation. Results of the test
<br /> indicated an effective radius of influence (ROI) of approximately 33 ft with a flow rate of approximately 16.8
<br /> standard cubic feet per minute (scfm) and a pressure drawdown of approximately 0.10 inches of water;
<br /> therefore, SVE was identified as a feasible remediation option for the mitigation of hydrocarbon affected soil in
<br /> the vadose zone beneath this site (Alton, 1995).
<br /> In March 1999, a 12-hour groundwater extraction test was performed by Park on monitoring well MW-11 at a
<br /> maximum sustainable flow rate of 4-gallons per minute (gpm) to evaluate the site for potential groundwater
<br /> extraction remediation as required by the SJCEHD. A groundwater capture zone for the extraction well was
<br /> estimated at approximately 110 ft. Based on the data collected during the pump test and the previous vapor
<br />
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