SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Jimco Truck Plaza - 2 - 10 November 2009 1022 East Frontage Road Ripon, Sar Joaquin County Comment_ The installation of nine monitoring wells indicated in CAP Figure 7 for the investigation work plan is approved. Please provide a detailed schedule for implementation of the investigation work plan in an email to me by 11 December 2009, and proceed immediately with well permits and access agreemems. The CAP recommendation for submitting a FP extraction system remedial work plan is not approved at this time. In future monitoring events, if FP is encountered in monitoring wells, you will measure the thickness of FP, attempt to hand bail each well containing FP; and properly contain and dispose the FP. You will also document the work in an email to me within one week of FP discovery and provide updates each following week, describe the FP removal action and include a table of dates when FP was encountered, measured thickness of FP, time of recovery, and volume of FP removed. After one month of hand bailing, a determination will be made whether a mechanical FP extraction system is more cost effective than hand bailing, and a remedial action work plan for FP will be requested. Further direction on FP removal may be included in subsequent responses to the above requested emails. While sodium persulfate and hydrogen peroxide are listed as examples of ISCO oxidants ("such as...") in the CAP, the text does not specify which oxidant(s) would be used during the bench scale testing and pilot study. The CAP also says ISCO injections will occur quarterly for two years, and CRA will conduct performance monitoring of ISCO in the same injection wells. A recommendation designating specific cxidant(s) would be beneficial prior to submittal of the bench scale testing and the pilot study work plan, to help design the monitoring program used to evaluate potential effects of the injections on the aquifer for the injection permit. As noted in the CAP, all injection of substances into the aquifer require an injection permit from this-office, specifically Order No. R5-2008-0149, Waste Discharge Requirements, General Order for In-Situ Groundwater Remediation at Sites with Volatile Organic Compounds, Nitrogen Compounds, Perchlorate, Pesticides, Semi-Volatile Compounds, Hexavalent Chromium and/or Petroleum Hydrocarbons, which may be downloaded from the Internet at http://www.waterboards.ca.gov/centralvalley/board decisions/adopted orders/general orders/r5-2008- 0149.pdf. By 30 December 2009, provide a response specifying the oxidant(s) proposed for ISCO. Also, provide a technical justification for the proposed use of combined injection/performance wells for ISCO, and the quarterly frequency of the ISCO injections for two years. If desired, you may revise the CAP cost of the ISCO remediation to show a one-time full scale ISCO injection with temporary injection points and use of the existing/approved proposed monitoring wells as performance/compliance points for the injection permit. Upon review of the information, we will provide a decision for submittal of an ISCO B1riT/PS work plan. Note that AGTs releases are not a part of the USTs cleanup program, and that we (UST program) are discussing this case with the AGT program staff, with the objective of integrating the approach for the two releases under one remedial action as the most cost effective means for reaching water quality goals. Further direction will follow this inter-program discussion. If you have any questions, please /Engineering tact me at (916)464-461 or via e-mail at jbarton@waterboards.ca.gov. Ve. es L.L. Barton, P. G. Geologist cc: Mr. Robert L'Heureux, SWRCB UST Cleanup Fund, Sacramento Ms Margaret Lagorio, San Joaquin Co, 600 E. Main St., Stockton 95202 Mr. Ron Scheele, Conestoga-Rovers Assoc., 5900 Hollis St., Ste. A, Emeryville, 94608