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I Ms. Margaret Lagorio, SJCEHD January 5,2005 <br /> Work Plan for Additional Site Assessment and Project No. 2033-15600-01 <br /> Evaluation of Remedial Alternatives <br /> Joe's Truck Plaza,Lathrop,California <br /> Page 4 <br /> In Sand A, TPHG and MTBE are currently reported (third quarter 2004) in wells MW-2 <br /> and MW-3. MTBE is also reported in wells MW-7 and MWO-2. MTBE impact east and <br /> northeast of the site has not been fully characterized in Sand A. The lateral extent of <br /> dissolved MTBE impact is shown on Figure 4. <br /> i <br /> One well (MWO-1X) is currently screened in the depth range of Sand B. TPHG and <br /> MTBE are currently reported in this well. MTBE was also reported in grab samples <br /> collected in Sand B at CPT-8, but was not reported in samples collected within Sand B at <br /> CPT-5. TPHG or other fuel oxygenates (including MTBE) were not reported in grab <br /> samples collected within Sand C at any of the CPT locations. <br /> PROPOSED SCOPE OF WORK <br /> i <br /> To address the concerns outlined in SJCEHD's letter of November 10, 2004, to further <br /> characterize the lateral extent of dissolved MTBE impact in Sands A and B, and to move <br /> the project toward implementation of active remediation, Stratus proposes to: <br /> i <br /> • Install two additional off-site groundwater monitoring wells (MW-9 and MW-11), <br /> screened within Sand A, at the locations of CPT-5 and CPT-8. <br /> • Install one additional on-site monitoring well (MW-10), screened within Sand A, <br /> south of well MW-3. <br /> I <br /> • Install one off-site well (MW-8), screened within Sand B, at the location of CPT-8. <br /> • Evaluate remedial options, including C-Sparge ozone injection, batch extraction of <br /> groundwater, DPE, and air sparging (AS). <br /> The proposed scope of work presented above has been subdivided into tasks 1 throughh 5. <br /> All geologic work will be conducted under the supervision of a State of California <br /> Registered Geologist or Registered Engineer, and will be conducted in accordance with <br /> standards established by Appendix A-Reports, Tri-Regional Board Staff Recommendation <br /> for Preliminary Investigations and Evaluation of Underground Tank Sites (April 2004) <br /> and SJCEHD guidelines. Additional information regarding Stratus' field practices and <br /> 1 procedures is presented in Appendix A. <br /> Task 1: Pre-Field Activities <br /> Following approval of this work plan by SJCEHD, the following activities will be <br /> implemented: <br /> • Secure an access agreement and an encroachment permit for installation of <br /> j <br /> off-site wells. <br /> K:Uoe's Truck Plaza\Work PlansUoes workplan 010505.doc <br /> 1 <br />