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_ URS <br /> December 1,2011 RECEIVED <br /> ' <br /> Ms.Natalia Subbotnikova <br /> DEC 0 <br /> 2 2011 <br /> ' San Joaquin County Environmental Health Department ENVIRONMENTAL HEALTH <br /> 600 E. Main Street PERMIT/SERVICES <br /> Stockton, California 95202 <br /> ' Subject: Transmittal of Revised Well Decommissioning Work Plan <br /> World Enterprises, Turnpike Road, Stockton, California <br /> ' Dear Ms. Subbotnikova: <br /> ' On behalf of Radio Shack Corporation, URS Corporation Americas(URS)has prepared this revised <br /> work plan describing procedures required to decommission three groundwater monitoring wells (MW- <br /> 1 through MW-3) at the World Enterprises site located on Turnpike Road, south of Downey Road, to <br /> Stockton, California (Figure 1). Specifically,the work plan discusses the disposal procedure of <br /> ' potential solid waste encountered during well decommissioning activities, as requested by the San <br /> Joaquin County Environmental Health Department(SJCEHD). <br /> ' SITE BACKGROUND <br /> The World Enterprises site is located in Stockton,California. From 1970 through 1978,this site was <br /> ' operated as a debris disposal site(debris from demolished buildings, including wood, rubble, concrete, <br /> and other fill materials) under San Joaquin Local Health District Use Permits to World Enterprises . <br /> ' On July 17, 2003, during an annual site inspection,the San Joaquin County Environmental Health <br /> Department(SJCEHD)staff measured methane gas concentrations up to 30,000 parts per million by <br /> volume(ppmV) (3 percent by volume)along the property boundary. As a result of this inspection, <br /> SJCEHD required Tandy Corporation(site owner,currently known as RadioShack)to assess whether <br /> the methane concentration along the property boundary was greater than 5 percent by volume and, if <br /> found to be greater than 5 percent by volume,to implement measures for controlling methane from <br /> ' leaving the site. RadioShack contracted with URS to assess the extent of methane at the World <br /> Enterprises site. Since 2004, URS has installed 10 gas-migration monitoring probes, 2 vapor <br /> extraction wells, and 3 groundwater monitoring wells at the World Enterprises site(Figure 2). <br /> ' In December 2005,a vapor extraction pilot test was conducted to evaluate the feasibility of installing a <br /> permanent landfill gas extraction system. During this test, vapor samples were collected from the two <br /> extraction wells and analyzed for volatile organic compounds(VOCs). Analytical results of these <br /> ' samples confirmed the presence of VOCs where the total VOC concentration in each of the vapor <br /> extraction wells was less than 5 ppmV. Based on these results,VOC constituents could be present in <br /> groundwater. To assess the presence or absence of VOC constituents in the groundwater, three <br /> ' groundwater monitoring wells (MW-1 through MW-3) were installed at the site on June 12, 2006. <br /> Following the installation of groundwater monitoring wells, groundwater samples were collected <br /> quarterly and analyzed for VOCs. Mr. Ross Atkinson (Regional Water Quality Control Board <br /> URS Corporation <br /> ' Crown Corporate Center <br /> 2870 Gateway Oaks Drive,Suite 150 <br /> Sacramento,CA 95833 <br /> Tel:916.679.2000 <br /> Fax:916.679.2900 H:%Wprocesst255321WorldEnterprise\Well Destruction\Revised Report 12-1-11.doc <br />