ARCHIVED REPORTS_2011 REVISED FEASABILITY STUDY

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z 1 INTRODUCTION Geomatrix Consultants (Geomatrix) conducted an in-situ biodegradation investigation at the 230 Industrial Avenue site (the Site) in October 20051. The in-situ push-pull tests (PPTs) were completed in wells M-1A and M-113, which are located in the proposed treatment zone at the Former Nestle Facility (Figure A.2-1). Geomatrix completed these tests to evaluate in-situ carbohydrate utilization rates and assess potential changes in aquifer conditions due to carbohydrate addition. A single-well PPT consists of two phases, (1) the injection ("push") phase and (2) the extraction ("pull") phase. During the injection phase, a test solution consisting of water, a reactive solute, and a conservative tracer, is injected into the aquifer surrounding the test well. After the injection, the solution is allowed to remain in the aquifer pore space near the well for approximately 24 hours to react with solid and dissolved-phase constituents (referred to as the lag time). The extraction phase is then initiated following this 24 hour period. During the extraction phase, water is periodically extracted from the test well and sampled to obtain concentrations of the reactive solute, tracer, and other target constituents in groundwater. 1.1 Background Information In-situ treatment was proposed to the California Regional Water Quality Control Board (RWQCB), Central Valley Region in the July 12, 2005 Final Work Plan for Initial Testing and Characterization Program, and in the subsequent November 28, 2005 addendum. These documents were subsequently approved by the RWQCB. The objectives of the in situ treatment were two-fold: (1) identify an area for implementing the potential in-situ bioremediation (ISB) remedy; and, (2) collect preliminary data to facilitate the design of an ISB pilot test program at the Site The addition of a carbohydrate solution to groundwater containing chlorinated volatile organic compounds (VOCs) is an effective in situ remedial approach at many sites. This approach stimulates native microbial populations and promotes the reduction of chlorinated VOCs by dehalo-respiration2 s, a. Carbohydrate is both an energy source and a carbon source that may increase the growth and viability of a variety of different groups of subsurface microorganisms when added to the groundwater system. Carbohydrate is fermented by subsurface microorganisms, producing final end-products including methane and inorganic carbon (as carbon dioxide or bicarbonate). Intermediate fermentation products are produced, including organic acids and hydrogen. The intermediate fermentation products are used by subsurface microbes to reduce solid and dissolved mineral constituents and other relatively oxidized species (called electron acceptors). Examples of naturally occurring and anthropogenic electron acceptors in aquifer systems include oxygen, nitrate, sulfate, ferric iron (Fe III), manganese (Mn IV), and carbon dioxide. These electron acceptors can be reduced by adding carbohydrate to groundwater. VOCs, including trichloroethylene (TCE), cis-1,2-dichloroethylene (cis-1,2- DCE), and vinyl chloride (VC) can also function as electron acceptors, and the reduction of these compounds can be enhanced microbiologically by adding carbohydrate to the aqueous system. The microbiologically-mediated reduction of these electron acceptors is called respiration, and microbes utilize the energy gained from these oxidation- reduction (redox) reactions. The redox processes that occur as a result of carbohydrate addition can be monitored by analyzing the oxidized and reduced species of electron acceptors in groundwater.