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.^ �..� Valley Motors - 2 - 10 October 2012 800 E. Main St., Stockton San Joaquin County • Pump and Ex-situ Treatment with Mn04 Injection (Recirculation P&T): Extracted groundwater from 4" diameter extraction well VM-9 would be treated by GAC and pumped into a holding tank, then an automated mixer would add Mn04 to create a 2% to 0.5% (Mn04 per cent mixture declining over time) aqueous solution in the GAC-treated water, to increase destruction of existing TCE/PCE. The Mn04 treated water would then be pumped into monitoring wells VM-1 and VM-2, or into one or more new injection wells as a closed loop system of injection and extraction, and doing so would create a hydraulic barrier to the chlorinated solvents plume without the offsite disposal or discharge to the sewer of a conventional batch P&T system (the sewer district banned continuous treatment and discharge). A total of 300,000 gallons of water would be treated and injected over two to four months of treatment. The Report cost for full scale Recirculation P&T was $91,500 based on installation of 6 new injection wells, and treatment and reinjection of 300,000 gallons of water. The Report recommended a Recirculation P&T pilot study ($16,000, which was included in the above total estimated cost of $91,500) that would involve extracting from VM-9 and, after the above treatment, injecting into upgradient monitoring wells VM-1 and VM-2, to evaluate performance of a hydraulic barrier for the chlorinated solvent plume that is currently migrating onsite. Recirculation P&T was recommended for one week of pilot testing since the majority of the equipment is already onsite and could be implemented reasonably fast. The Report and recommendations for Recirculating P&T are acceptable. The Work Plan for the Pilot Study for Recirculating P&T is necessary and appropriate to evaluate the recommended remediation technology, and is approved. Please submit a Notice of Intent (NOI Form 200) for Central Valley Regional Water Quality Control Board Waste Discharge Requirements for General Order For Land Disposal of Groundwater or Surface Water From Cleanup Of Petroleum Pollution, Order No. R5-2003-0044, which may be downloaded from the following web link: http://Www.waterboards.ca.gov/publications f6rms/forms/docs/f6rm200.pdf Fill out Form 200 pages 5 and 6, and submit the draft NOI to me for my evaluation by email as an attachment or by mail by 15 November 2012. Do not send any fees at this time. Further directives will follow. A Recirculating P&T Pilot Study report is due 30 January 2013. You may contact me with your q stions by phone at (916) 464-4615 or by e-mail at jbarton(c�waterboards.ca.gov. -'- ;; James L.L. Barton, P.G. Engineering Geologist cc: Kelli Graver, State Water Resources Control Board UST Cleanup Fund, Sacramento Nuel Henderson, San Joaquin County Environmental Health Department, Stockton Victor Cherven, Upgradient Environmental Consultants, 3369 Kimberly Rd., Cameron Park 95682