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31 October 2011 AGE-NC Project No. 99-0682 Page 2 of 9 3.0. EVALUATION OF GROUND WATER REMEDIAL ALTERNATIVES To date an evaluation of ground water remediation alternatives halnot been completed for the site. In a letter dated 08 September 2011, San Joaquin County Environmental Health Department (SJCEHD)staff directed preparation of a ground water remediation feasibility study work plan (Appendix B). In accordance with SJCEHD directives, AGE has provided the following evaluation of applicable ground water remedial options. 3.1 . IN-SITU CHEMICAL OXIDATION Advanced Oxidation Processes (AOP) refers to a set of treatment options used to remediate organic and inorganic wastes from water.AOP are commonly used to remediate gasoline from underground fuel tank leaks and to treat waste water. The most predominant radical found in the reaction is the hydroxyl radical. The hydroxyl ion generally grabs hydrogen atoms from the organic molecules in contaminated waters and causes organic molecules to become unstable and eventually breakdown. The end product of these reactions is generally small amounts of mineral acid from halogens, nitrogen or sulfur present in soil or ground water, bicarbonate, and water. In general four common AOP's are used in industry to remediate hydrocarbons in soil and w ground water: ozone, hydrogen peroxide, Fenton's reagent ( eg nerally a mixture of� }e hydrogen peroxide and acid), brand named RegenOxTm and persulfate. For the site, "s X02 hydrogen peroxide/modified Fenton's reagent and RegenOxTm have been chosen for evaluation based on the lateral/vertical extent of residual hydrocarbons in "drowned" soil 1-L, and ground water and based on sample concentrations reported during historical site t- investigations. Figures 3 through 6 illustrate in plan view the estimated lateral extent of dissolved and adsorbed TPH-g in soil and ground water. It is assumed that formerly active SVE remediation has mitigated a majority of the vadose zone hydrocarbon impact and as such the pre-remediation adsorbed hydrocarbon plume from near surface grade to 30 feet bsg has not modeled. 3.1 .1. Hydrogen Peroxide/Modified Fenton's Reagent Hydrogen peroxide is widely used in the environmental industry to remediate hydrocarbon impact to soil and ground water. Hydrogen peroxide is a compound with an oxygen-oxygen single bond and is the simplest peroxide and oxidizer. Hydrogen peroxide is a clear liquid, which is slightly more viscous than water. Hydrogen peroxide is generally supplied in a semi-diluted forrwknown as 35% industrial grade. At this dilution the hydrogen peroxide is Advanced Geo Environmental,Inc.