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L <br />San Joaquin County <br />Environmental Health Department <br />600 East Main Street <br />Stockton, California 95202-3029 <br />Website: www.sjgov.orglehd <br />Phone: (209)468-3420 <br />Fax: (209) 464-0138 <br />September 24, 2010 <br />Mr. Donald Helsel <br />Earthgrains Baking Companies, Incorporated <br />2651 South Airport Way <br />Stockton, California 95206 <br />Subject: Earthgrains Baking Companies, Incorporated <br />2651 South Airport Way <br />Stockton, California 95206 <br />Dear Mr. Helsel: <br />DIRECTOR <br />Donna Heran, REHS <br />PROGRAM COORDINATORS <br />Robert McClellon, REHS <br />Jeff Carruesco, REHS, RDI <br />Kasey Foley, REHS <br />Linda Turkatte, REHS <br />The San Joaquin County Environmental Health Department (EHD) has received and <br />reviewed Revised Remedial Evaluation Report (report), dated 15 June 2010, prepared by <br />your consulting firm, PSC Industrial Outsourcing, LP (PSC), for the above -referenced <br />subject site. The report was submitted in response to discussions between personnel from <br />the EHD and PSC on 5 April 2010, and a directive from the EHD by letter dated 12 April <br />2010 to perform remediation at the core of the petroleum hydrocarbon plume to reduce the <br />contaminant mass. This report provides a more detailed evaluation of three remedial <br />alternatives first presented by PSC in Feasibility Study/Remedial Evaluation and Case <br />Closure Request Report, dated 7 October 2009. <br />PSC compared In-situ Chemical Oxidation (ISCO), enhanced bioremediation by <br />BioSparging, and In-situ Air Stripping to site specific conditions and concluded that ISCO <br />would be the most effective method for removing petroleum hydrocarbon contaminants <br />based on implementation, contaminant reduction, cost, and short- and long-term <br />effectiveness. PSC recommends performing a pilot study using a modified Fenton's <br />Reagent application developed by In-situ Oxidation Technologies, Inc. (ISOTEC). PSC <br />states that the modified Fenton's Reagent transfers contaminant mass from the adsorbed <br />phase into the dissolved phase where the oxidation process occurs and oxygen is produced, <br />thus enhancing bioremediation and further reducing dissolved contaminant concentrations. <br />PSC states that this technology has been used in the Central Valley of California with <br />successful results. PSC proposes to target the sandy and silty sand intervals at <br />approximately 45 to 52 feet and 60 to 70 feet below surface grade by selecting seven <br />injection locations in an area of approximately 3,000 square feet near the former 6,000 - <br />gallon gasoline underground storage tanks, as illustrated on Figure 12 of the report. <br />The EHD approves the ISCO pilot test using ISOTEC's Modified Fenton's Reagent; <br />however, prior to submitting a work plan for the ISCO pilot test, you must first contact the <br />