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EOuueO G.BROWN JR. <br /> •Aa'aaa a'• MAnnew ROORIouaz <br /> Water Boards OO.Nu.nnH.n,.L FRa,..,Ien <br /> Central Valley Regional Water Quality Control Board <br /> 26 March 2015 <br /> Torrey Harding <br /> Diamond Foods, Inc. <br /> 1050 South Diamond Street <br /> Stockton, CA 95205 <br /> NOTICE OF APPLICABILITY OF GENERAL ORDER NO. R5-2015-0012-003, IN-SITU REMEDIATION <br /> PILOT TEST, DIAMOND FOOD FACILTY, 1050 SOUTH DIAMOND STREET, STOCKTON, SAN <br /> JOAQUIN COUNTY <br /> Diamond Foods, Inc. (Discharger) submitted a completed Notice of Intent, dated 19 December 2014, <br /> requesting coverage under General Order No. R5-2015-0012, General Waste Discharge Requirements <br /> for In-situ Groundwater Remediation and Discharge of Treated Groundwater to Land. Based on <br /> information in your submittal, it is our determination that this project meets the required conditions to be <br /> approved under Order No. 2015-0012. All of the requirements contained in the general order are <br /> applicable to your project. You are assigned Order No. R5-2015-0012-003. <br /> Project Location: <br /> The project is in San Joaquin County, Township 1 N, Range 7E, Section 45, Mount Diablo Baseline & <br /> Meridian. Assessor's Parcel No. 155-32-019, Latitude 37°56'56.3" N, Longitude 121015'22.5"W. <br /> Project Description: <br /> The Diamond Foods facility has been operating as mainly a walnut processing plant since the 1950s. <br /> Hexavalent chromium was previously used as corrosion inhibitor for a former cooling tower at the site, and <br /> is believed to be the source of hexavalent chromium groundwater impacts immediately north of the main <br /> processing building. The Discharger is proposing a field pilot test to evaluate the effectiveness of in-situ <br /> treatment of the hexavalent chromium using calcium polysulfide (Cascade®) based on previous bench- <br /> scale testing. The pilot test was proposed in 19 December 2014 Pilot Study Work Plan prepared by <br /> Cardno ATC for the site. <br /> For the pilot study, the Discharger proposes to inject 1,500 gallons of calcium polysulfide solution under <br /> pressure into groundwater monitoring well MW-3, followed by 100 gallons of chase water to push the <br /> solution into the formation. A packer will be used to seal off the well at the top of the well screen and the <br /> calcium polysulfide solution will be injected under a maximum pressure of 40 pounds per square inch. <br /> The calcium polysulfide is intended to create reducing conditions in the groundwater to convert the <br /> hexavalent chromium into trivalent chromium. The Discharger will install two observation wells in the <br /> treatment zone to observe the effectiveness of the pilot test in the groundwater around monitoring well <br /> MW-3. <br /> KARL E. LONGLEY SCO, P.E.,CHAIR I PAMELA C. OnecooN P.E., BCEE,EXECUTIVE OFFICER <br /> 11020 Sun Canter ONVB#200.Rancho Cordova,CA 95670 1www.waNrooarea.ca.gov/cenhalvelby <br /> 0 RII.Into R.RFR <br />