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J.M. Equipment page 2 <br /> 1245 W. Charter Way, Stockton November 15, 2010 <br /> The selection of source removal by advancing LDBs over other potentially effective <br /> remedial alternatives for removing some of the contaminated soil, is supported by site <br /> specific conditions. Prior to adding an oxygen releasing compound, you must show <br /> conclusions that the subsurface is oxygen deficient or would benefit from oxygen <br /> releasing compounds. Typically, biological plate counts, oxygen measurements, and <br /> nutrient assessment are provided to support these conclusions but none were included <br /> in the RAP. <br /> Without ORC cost and amount estimates included in the RAP and without a supporting <br /> demonstration that the subsurface is oxygen deficient, the EHD cannot approve ORC <br /> use at this time. Please provide the EHD with data to support the conclusion that use of <br /> an oxygen releasing compound would benefit the site's subsurface ability to mitigate the <br /> petroleum impact. If supported, you may submit a revised pilot plan that includes a cost <br /> breakdown and estimate of the amount ORC to be added to each LDB. <br /> The EHD agrees that installing a perforated pipe (well casing) into LDB-3 & 4 may be <br /> advantageous for future monitoring, injection, and/or extraction purposes if conditions <br /> warrant. The EHD recommends that perforated casings be added to LDB-1 & 2 also. <br /> Whereas the duration of a one-time ISCO application of ORC is limited, the installation <br /> of a remediation well casing in each LBD may provide continuous monitoring or <br /> additional remedial uses if site conditions warrant. <br /> Please submit a revised RAP that addresses the EHD concerns noted. Thank you for <br /> your cooperation in continuing your investigation at the site. If you have any questions, <br /> you may cntact Michael Infurna, at (209)468-3454. <br /> Michael J. Infurna Jr., IREHS Nuel C. Henderson Jr., PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> C: Mr. James L. Barton, CVRWQCB <br /> Mr. Mark Owens, SWRCB <br /> Ms. Tamorah Bryant, Geological Technics Inc., 1101 7`" St. Modesto, CA 95354 <br />