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N San Joaquin County Environmental Health Department DIRECTOR Donna Heran, REHS 600 East Main Street Stockton , California 95202 -3029 PROGRAM COORDINATORS i_ufu� Robert McClellon, REHS — Jeff Carruesco, REHS, RDI O �P Kasey Foley, REHS 4 FoR Website: ww09)468. 3420 d Linda Turkatte, REHS Phone: (209) 468-3420 Fax : (209) 464-0138 December 15 , 2011 Gary Stallworth 602 California Street Stockton , CA 95202 Subject: Stallworth Auto Sales 602 California Street Stockton , CA 95202 The San Joaquin County Environmental Health Department (EHD ) has reviewed Ground Water Remediation Feasibility Study Work Plan (Study) dated October 31 , 20113 submitted on your behalf by Advanced Geo Environmental , Inc. (AGE ) and has the following comments. I In the Study AGE discusses four remedial options for addressing the petroleum hydrocarbon contamination persistent in the groundwater and saturated soil at this site . The options discussed were in-situ chemical oxidation (ISCO ) , enhanced aerobic bio- remediation , air sparging and oxygen release compound advanced (ORC-advanced ) . AGE did not compare the listed options for cost, except to state in general terms that some processes would take longer and therefore cost more. AGE recommends conducting a 4-week pilot test utilizing a form of ISCO called Fenton 's Reagent, going on to say they will utilize in the pilot test " . . . a solution of 5% hydrogen peroxide (possibly with ferrous sulfate ) and an optimum pH (3-5) adjustor, using muriatic or sulfuric acid ( 1 % acid )" . AGE proposes injecting the Fenton 's Reagent into onsite wells MW-1A and MW-8 and utilizing onsite , downgradient wells MW-6 and MW-7 as compliance wells. Baseline sampling of these four wells is proposed to be done prior to the injection ; additional sampling to be done following the second weekly injection and following the fourth weekly injection . AGE further describes that a mixture of approximately 800 gallons of a 5% hydrogen peroxide solution , in which they have mixed one liter of muriatic acid , will be injected into wells MW- 1A and MW-8 per weekly injection event. No mention is made of when , or if, the ferrous sulfate will be added , though Fenton 's Reagent is , by definition , a solution of hydrogen peroxide and iron catalyst, and the function of pH adjustment by acid is to maintain solubility of the iron activator. Per the Interstate Technology Regulatory Council ( ITRC) Technical and Regulatory Guidance for In Situ Chemical Oxidation of Contaminated Soil and Groundwater, second edition January 2005 (Guidance Document) , many factors must be addressed when planning an ISCO injection , including : delivery method , reaction rates , temperature , pH , concentration of the reactants , stoichiometry of the reactions , catalysts , reaction by- products and system impurities (e .g . , natural organic matter, oxidant scavengers , etc . ) .