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<br /> April 28, 2006 MAY 12 2 2006
<br /> Mr. Robert McClellon ENVIRONIVILENT HEALTH
<br /> Supervisor R.E.H.S. PERMIT/SERVICES
<br /> San Joaquin County Environmental Health Department(SJCEHD)
<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 /> URS has prepared this letter report on behalf of RadioShack to describe the quarterly monitoring field
<br /> activities completed at the World Enterprises site in Stockton,California,on March 10, 2006, and to
<br /> summarize the results of these monitoring activities.
<br /> This report includes into the following sections: Background,Field Activities,Results,and Conclusions
<br /> and Recommendations.
<br /> BACKGROUND
<br /> The World Enterprises site in Stockton, California, was formerly permitted as a debris disposal site;the
<br /> debris was from demolished buildings and included wood,rubble,concrete,and other fill materials. On
<br /> July 17,2003,Mr. Robert McClellon and Mr.Ted Tasiopoulos of SJCEHD conducted an annual
<br /> inspection at the World Enterprises site that included the measurement of the methane concentration
<br /> from nine temporary boreholes located along the perimeter of the site. As a result of this annual
<br /> inspection,URS has completed three phases of field investigations to assess the extent of the methane at
<br /> the site. On April 7, 2004,URS installed four gas-migration monitoring probes at the World Enterprises
<br /> site. On October 12, 2004,URS installed four dual-completion gas-migration monitoring probes at the
<br /> World Enterprises site. On June 1 and 2, 2005, URS installed two soil vapor extraction wells and two
<br /> gas-migration monitoring probes at the World Enterprises site(Figure 1).The quarterly monitoring
<br /> activities have been conducted since July 2004.
<br /> FIELD ACTIVITIES
<br /> On March 10,2006, each probe was measured for methane, oxygen, and carbon dioxide using a hand-
<br /> held,portable GEM 2000 landfill gas monitor. These measurements were recorded in a field book.
<br /> RESULTS
<br /> The methane concentrations in VW-1, VW-2,VW-3, VW-7S,VW-7D, VW-8S, VW-8D, VW-9, and
<br /> VW-10 were 0 percent.The methane concentrations in VW-4,VW-5S,VW-5D, VW-6S, VW-6D,
<br /> EW 1, and EW-2 were 1.7%, 6.6%, 4.1%, 7.8%,2.8%, 14.8% and 18.5%,respectively. The oxygen
<br /> concentration in all probes ranged from 1.4 to 21.1 percent. The carbon dioxide concentration in all
<br /> probes ranged from 0.6 to 27.4 percent. The results for each probe are summarized in Table 1.
<br /> URS Group, Inc.
<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\WorldEnterprise\Quarterly Rpt\1Q06\CovLtrRpt.doc
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