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V NO, <br /> Shockey Trucking May 24, 2010 <br /> 850 Milgeo, Manteca Page 3 of 3 <br /> 7. In the CAP, AGE recommends one of two corrective action alternatives for ground <br /> water remediation: ozone sparging, which has already been tested with no <br /> measurable ground water contaminant reduction; and RengenOx injection using <br /> massive quantities of the substance (45,000 pounds). The EHD has concerns with <br /> the distribution and effectiveness of these oxidants in the subsurface. Please <br /> provide an ozone mass:TPH-d mass budget estimate for further evaluation. <br /> The EHD believes that limited point source removal of contaminated soil and ground <br /> water should be reconsidered. The area of former UST-1 has been identified as the <br /> source of contamination; MW-4 is positioned in the area having the most impact soil <br /> (majority in the vadose zone) and the highest ground water contaminant concentrations. <br /> This impacted area remains undeveloped and is accessible. Contaminant mass in the <br /> ground water appears limited vertically and laterally due to the flat gradient (0.0001- <br /> 0.0004 ft./ft.) at the site. The limited ground water removal from MW-1, MW-4, and MW-6 <br /> maybe the most cast effective corrective action measure in reducing the estimated 10 <br /> gallons of dissolved TPH-d. <br /> Please prepare and submit a work plan (W.P.) for an SVE pilot test (utilizing MW-4 for <br /> extraction) by 15 July 2010. MW4 is located in the source area and constructed with a 4- <br /> inch diameter casing with a slotted screen from 8 feet to 28 feet. By applying a <br /> continuous vacuum on MW-4, collecting vapor samples for analysis at specified intervals <br /> during a 5 day test period, it may demonstrate if mass recovery is sustainable, effective, <br /> and feasible for soil remediation. No additional wells will be required for the extended <br /> test, and surrounding MWs could be monitored to evaluate vacuum influences that maybe <br /> occurring beyond MW-4 during the test period. If a significant TPH-d contaminant mass <br /> recovery rate can be sustained over time, additional pilot testing with the additional wells <br /> may be justified. <br /> In addition to the SVE W.P., prepare and submit an ozone:TPH-d budget for the proposed <br /> ground water remediation by July 15, 2010. <br /> If you have any further questions regarding this matter, please contact Harlin Knoll at <br /> (20p) 468-3442. 4-1 <br /> 14�- le� <br /> Harlin Knoll, REHS Nuel C. Henderson, Jr., PG <br /> Senior Registered Environmental Health Specialist Engineering Geologist <br /> c: James L. L. Barton, Central Valley Regional Water Quality Control Board, 11020 Sun <br /> Center Drive #200, Rancho Cordova, CA 95670 <br /> Brian Millman, Advance GeoEnviron mental, Inc., 837 Shaw Road, Stockton, CA 95215 <br />