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URS
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<br /> October 3, 2005
<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: Soil Vapor Extraction Well and Gas Migration Monitoring Probes
<br /> 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
<br /> at the World Enterprises site in Stockton, California, on June 1 and 2, 2005, to install two soil vapor
<br /> extraction wells and two gas migration monitoring probes (Figure 1). In addition, this letter report
<br /> describes the quarterly monitoring events conducted at this site on June 9, 2005, and August 29, 2005,
<br /> and summarizes the monitoring results.
<br /> BACKGROUND
<br /> The World Enterprises site in Stockton, California, was formerly permitted as a debris disposal site;
<br /> the debris, from demolished buildings, included wood, rubble, concrete, and other fill materials. On
<br /> April 7, 2004, URS installed four single-completion gas migration monitoring probes (VW-1, VW-2,
<br /> VW-3, and VW-4) at the World Enterprises site. During the July 9, 2004, monitoring events, methane
<br /> was measured within probe VW-4 at a concentration of 18.9 percent. As a result of this measurement,
<br /> San Joaquin County Environmental Health Department (SJCEHD) transmitted a letter to RadioShack,
<br /> dated July 13, 2004, "requiring the site owner to submit a remediation plan within sixty (60) days of
<br /> receipt of this letter to EHD for methane gas releases at the site." According to California Code of
<br /> Regulations (CCR) Title 27, Division 2, Subdivision 1, Chapter 3, Subchapter 4, Article 6, Section
<br /> 20919.5(c)(3), ". . . the plan shall describe the nature and extent of the problem and the proposed
<br /> remedy."
<br /> A work plan to install four additional gas-migration monitoring probes at the site was transmitted to
<br /> SJCEHD for approval on September 13, 2004. This work plan provided an explanation that since the
<br /> size of the methane plume was not known at this time, the transmittal of a remediation plan would be
<br /> premature, and that before a remediation plan was prepared, a better understanding of the extent of the
<br /> methane plume along the northern boundary of the site was needed. Following SJCEHD's review of
<br /> the September 13, 2004, work plan, SJCEHD transmitted its review comments in an e-mail message
<br /> on September 23, 2004. A work plan addendum to address SJCEHD's review comments was trans-
<br /> mitted to SJCEHD for approval on October 4, 2004. The work plan and addendum were approved by
<br /> URS Corporation
<br /> Crown Corporate Center
<br /> 2870 Gateway Oaks Drive, Suite 300
<br /> Sacramento,CA 95833
<br /> Tel:916.679.2000
<br /> Fax:916.679.2900 K:\Wprocess\25532\WorldEnterprise\Quarterly Rpt\3Q05Uuly.doc
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