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t <br /> tm <br /> 0 9 <br /> July 28, 2006 <br /> ZOOG AUG -1 P11 2; p9 <br /> Mr.Robert McClellon <br /> Supervisor R.E.H.S. S 4 N .i 0,,,,;, l <br /> C` t ,3 !TY <br /> San <br /> 304 Ea s Webein or Avenue, loHealth Department H! N � A"A M4EW T <br /> Stockton, California 95202-2708 <br /> Subject: Groundwater Monitoring Well Installation Report and Quarterly Monitoring Report <br /> World Enterprises Site <br /> Stockton, California <br /> Dear Mr. McClellon: <br /> URS has prepared this letter report on behalf of RadioShack to describe the field activities completed at <br /> the World Enterprises site in Stockton, California on June 12, 2006 to install three groundwater <br /> monitoring wells,and the results of these field activities (Figure 1). In addition,this letter report describes <br /> the monitoring activities completed at this site on June 19, 2006 and June 29,2006 for the second quarter <br /> of 2006,and summarizes the results of these monitoring activities. <br /> This report has been organized into the following sections: Background,Field Activities,Results,and <br /> Conclusions and Recommendations. <br /> BACKGROUND <br /> The World Enterprises site is located in Stockton, California. This site was operated as a debris disposal <br /> site(debris from demolished buildings, including wood,rubble,concrete, and other fill materials)under <br /> San Joaquin Local Health District Use Permits to World Enterprises from 1970 to 1978. During an annual <br /> inspection of the site on July 17, 2003,the San Joaquin County Environmental Health Department <br /> (SJCEHD) staff measured methane gas concentration up to 30,000 parts per million volume(ppmV) (3 <br /> percent by volume) along the property boundary. As a result of this inspection, SJCEHD required Tandy <br /> Corporation(site owner and currently known as RadioShack)to assess whether the methane <br /> concentration along the property boundary was greater than 5 percent, and if the methane concentration <br /> along the property boundary was found to be greater than 5 percent,to implement measures for <br /> controlling methane from leaving the site,. Since 2004,URS has installed 10 gas-migration monitoring <br /> probes and two vapor extraction wells at the World Enterprises site(Figure 1)during our field <br /> investigation activities. <br /> URS conducted a vapor extraction pilot test in December 2005. During this test,vapor samples were <br /> collected from the two extraction wells and analyzed for volatile organic compounds (VOCs). The <br /> analytical results for the VOC analysis showed that VOCs were present,but the total VOC concentration <br /> in either of the vapor extraction wells was less than 5 ppmV. Based on these results,there was a potential <br /> for VOC constituents to be present in groundwater.To assess the presence or absence of VOC <br /> constituents in the groundwater, a work plan to install three groundwater monitoring wells at the site, <br /> along with the completed Well/Pump Permit and associated permit fees, was transmitted to SJCEHD on <br /> May 18,2006. SJCEHD approved Well/Pump Permit prior to the start of the field activities. <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 K:\Wprocess\25532\WorldEn[erprise\Quarterly Rpt\2Q06\CovLvRptdoc <br />