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terra <br /> phase <br /> e n <br /> g i n e e r ) n g <br /> July 13, 2016 <br /> William Brattain, P.E. <br /> Water Resources Engineer <br /> Private Sites Cleanup Unit <br /> 11020 Sun Center Drive, #200 <br /> Rancho Cordova, CA 95670 <br /> sent via email to Bill.Brattain@waterboards.ca.gov <br /> Subject: Work Plan to Install a Sub-Slab Venting System and Abandon Soil Vapor Extraction Wells at <br /> the C&5 One Hour Martinizing Facility, 5756 Pacific Avenue, Stockton, California <br /> Dear Mr. Brattain: <br /> On behalf of Robinhood Plaza Shopping Center, LLC. ("Robinhood Plaza"), this Work Plan presents <br /> methods and procedures to install a passive sub-slab venting system beneath the C&S One Hour <br /> Martinizing Facility, 5756 Pacific Avenue,Stockton, California ("the Site").This work plan also includes <br /> proposed methods for abandonment of soil vapor extraction wells at the Site. <br /> SITE BACKGROUND <br /> Initial Investigation and Remedy Implementation <br /> Results of a Phase I/Phase II investigation at the Site revealed the presence of low concentrations of <br /> tetrachloroethylene (PCE, a common dry cleaning solvent), and other associated volatile organic <br /> compounds (VOCs) in the soil and soil gas directly beneath the dry cleaning facility.The dry cleaning <br /> facility no longer uses PCE. Several phases of investigation were conducted to address the detections of <br /> PCE in soil gas including a utility survey and a subsequent soil and grab groundwater investigation, and <br /> additional soil gas investigations. Based on the results of those investigations, impacts associated with <br /> this site were limited to soil gas in the immediate vicinity of the former dry cleaning machine (LFR, <br /> 2009). <br /> A soil vapor extraction (SVE) system was installed to address the limited soil gas impacts and was <br /> started up on October 27, 2010.The SVE system was shut down on February 10, 2011 due to very low <br /> concentrations of PCE in the system influent. <br /> Post Remedy Monitoring <br /> On behalf of Robinhood Plaza, ARCADIS submitted a No Further Action (NFA) request report (ARCADIS <br /> 2012)for the subject site on August 31, 2012, based on the results of soil and groundwater data <br /> collected from the Site, and the performance of the SVE remedy.The August 2012 closure request was <br /> based on one round of post SVE rebound monitoring conducted during March 2011, approximately one <br /> month after shut down.The RWQCB did not concur with the request for closure, and requested <br /> additional data to further characterize post remedy concentrations of VOCs in soil gas beneath the site. <br /> In response to that request, an additional three rounds of post-remedy soil gas data were collected in <br /> Terraphase Engineering Inc.12330 E.Bidwell Street,Suite 2111 Folsom,California 95630 1 www.terraphase.com <br />