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f <br /> i r ; <br /> y , c7m6gtcaI Technics Inc. Page 2 <br /> Site Closure Plan <br /> Project No.750.2 <br /> August 11,2005 <br /> On June 12, 2000, GTI and Del-Tech Geo Technical (Del-Tech) performed a vapor a <br /> extraction pilot test at the site. Laboratory and field test results indicate the site is conducive <br /> to remediation by vapor extraction. <br /> d <br /> On June 12, 2000, Ms. Lori Duncan of San Joaquin County Environmental Health <br /> Department (SJCEHD) requested in writing that a work plan be prepared to define the lateral <br /> and vertical extent of the groundwater plume at the site. 1!On June 29, 2000, GTI prepared a <br /> work plan proposing the installation of two water table monitoring wells and one deep, <br /> discretely screened monitoring well. Ms Duncan approved the work plan on: July 7, 2000. <br /> The work was performed during the week of October 16, 2000. <br /> On January 30, 2001, GTI prepared and submitted the'�Corrective Action Plan (Revised) <br /> Vadose Zone Remediation. The CAP discusses GTT's proposed methodology,'for mitigation <br /> of the documented petroleum hydrocarbon contamination"at the site by vapor extraction. The <br /> CAP also discusses the confirmation testing outlined in this work plan. Ms Duncan approved <br /> the CAP, as submitted, in a letter dated April 02, 2001. E <br />! In February 2002 the soil vapor extraction (SVE) system,was initiated and has operated for <br /> approximately one year. On January 21, 2003, GTI; submitted the Vapor Extraction <br /> Treatment System Monitoring Report. The report indicated that approximately 50% of the <br /> petroleum hydrocarbons contained in the subsurface have::been removed, the groundwater at <br /> this site is free of petroleum hydrocarbon contamination, and possibly as much:as 600 gallons <br /> of gasoline may remain in the vadose zone. The report 1also recommended that the site be <br /> considered for closure. j <br /> E� I <br /> In a letter dated February 18, 2003, SJCEHD requested that the well extraction cycle be <br /> utilized to address lower screen intervals and that GTI may consider switching methods of <br /> contaminant destruction, such as changing to carbon canisters to lower operational costs. <br /> On March 28, 2003, GTI submitted the Additional Site Characterization—Soil Borings Work <br /> Plan. Ms Duncan approved the work plan, with reservation, in a letter dated'April 8, 2003. <br /> The soil borings were advanced on September 5, 2003 and GTI submitted the resulting <br /> Interim Soil Investigation Report on October 2, 2003. As per the April 8, 2003 SJCEHD <br /> directive, the SVE system was restarted on December 9, 2003 and ran until January 14, 2004. <br /> i <br /> A new vapor extraction — granulated activated carbon ;�(SVE-GAC) system was installed <br /> during the summer of 2004. The SVE-GAC was started on September 24, 2004 and ran until <br /> April 12, 2005. The SVE-GAC was not operational, due,to repairs, for three weeks between <br /> December 2004 and January 2005. <br /> L� <br /> On May 1 B <br /> y 6, 2005, GTT prepared and submitted a Rask Evaluation &Appendix Site Closure <br /> Checklist recommending the COE site be considered for No Further Action,' On July 13, <br /> 2005, SJCEHD submitted a Case Closure Summary to the CRWQCB. The CRWQCB <br /> i <br /> ii. I <br />