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February 3, 2010 <br />Mr. Robert McClellon <br />Supervisor R.E.H.S. <br />San Joaquin County Environmental Health Department <br />304 East Weber Avenue, Third Floor <br />Stockton, California 95202-2708 <br />Subject: Quarterly Monitoring Report <br />World Enterprises Site <br />Stockton, California <br />Dear Mr. McClellon: <br />gno-EcErSVED <br />FEB 0 5 2010 <br />ENVIRONMENT HEALTH <br />PERMIT/SERVICES <br />URS Corporation Americas (URS) has prepared this letter report on behalf of RadioShack. This <br />report provides a description of the monitoring activities completed at the World Enterprises site in <br />Stockton, California (Figure 1), during the fourth quarter of 2009 and summarizes the results of <br />these monitoring activities. This report is organized in the following sections: Background, Field <br />Activities, Results, and Conclusions and Recommendations. <br />BACKGROUND <br />The World Enterprises site is located in Stockton, California. From 1970 to 1978, this site operated <br />as a debris disposal site (debris from demolished buildings, including wood, rubble, concrete, and <br />other fill materials) under San Joaquin Local Health District Use Permits to World Enterprises. On <br />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 <br />by volume (ppmV) (3 percent by volume) along the property boundary. As a result of this <br />inspection, SJCEHD required Tandy Corporation (site owner, currently known as RadioShack) to <br />assess whether the methane concentration along the property boundary was greater than 5 percent <br />by volume, and if found to be greater than 5 percent by volume, implement measures for <br />controlling methane from leaving the site. RadioShack contracted with URS to assess the extent of <br />methane at the World Enterprises site. Since 2004, URS has installed 10 gas -migration monitoring <br />probes, 2 vapor extraction wells, and 3 groundwater monitoring wells at the World Enterprises site <br />(Figure 1). <br />As a result of the field investigations, methane concentrations along a portion of the property <br />boundary were found to be above 5 percent by volume. In September 2006, a passive soil vapor <br />extraction trench was installed to control methane from leaving the site. <br />In December 2005, a vapor extraction pilot test was conducted to evaluate the feasibility of <br />installing a permanent landfill gas extraction system. During this test, vapor samples were collected <br />from the two extraction wells and analyzed for volatile organic compounds (VOCs). Analytical <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 <br />H:\Wprocess\25532\WorldEnterprise\Quarterly Rpt\2009\4Q09\020310.doc <br />