PSA - Groundwater Remedy and Quarterly Sampling Plan - Oliver Industrial Park - Hull and Assoc.

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Hull & Associates Inc. Page 16 Provect-IR: Provect-IR contains ZVI to uniquely elicit ISCR reactions, and it is composed of a hydrophilic, solid and complex carbon source hence it should generate little or no methane (< 5 mg/L). Provect-IR consists of various organic hydrogen donors, such as propionate, yeast extract and kelp meal that target the production of H2 levels that effectively stimulate the reductive dechlorination process. In addition Provect-IR also incorporates the oxygen scavenger sodium sulfite and the methane inhibitor red yeast rice, making it suitable to address multiple facets and areas of concern during the remedial process. A more extensive description of the purpose of each reagent is presented below. Oxygen Scavenger (sodium sulfite): Reductive dechlorination only occurs in the absence of oxygen; and, the chlorinated solvent actually substitutes for oxygen in the physiology of the microorganisms carrying out the process. As a result of the use of the chlorinated solvent during this physiological process it is at least in part dechlorinated. The site shall have introduced to the subsurface an oxygen scavenger to ensure that this process would occur immediately. Zero Valent Iron (ZVI): ZVI may chemically be thought of having been the product of the positively charged metal ions receiving electrons to become the electrically neutral pure metal. The term "reduction" is applied to any chemical reaction that added electrons to an element. Thus ZVI is a reduced material. In a similar manner, the chemical term "oxidation" refers to any chemical reaction that removes electrons from a material. For a material to be reduced, some other material must be oxidized. In the reduction of a chlorinated compound the zero valent iron is oxidized. Zero valent iron enhanced abiotic degradation of chlorinated volatile organic compounds (CVOCs) is essentially a reductive dechlorination process, which uses granular cast iron as the reducing agent, and produces final reaction products such as ethane, ethene, and chloride ions in the degradation of TCE. During this treatment process, the corrosion of iron by water dominates the chemical processes. The corrosion of iron by water results in ferrous ion generation, hydroxyl ion generation, and hydrogen gas generation. This results in a decrease in ORP (oxidation/reduction potential; that is, reducing conditions are produced) and an increase in pH. Accordingly, the end products of this reaction are ferrous iron, chloride ions, and the dehalogenated compound. Frequently remedial sites show insignificant or incomplete dechlorination, especially those with high aquifer sulfate levels. It is generally overlooked that the rapid conversion of sulfate to toxic free sulfide during bacterial reductive dechlorination plays a significant role in the "stalling" of the biotic stalling frequently observed. Accumulation of free sulfide is especially important in sites that display both high sulfate and low available iron. Reductive dechlorination inhibition by free sulfide has been observed in microcosms conducted for high sulfate field sites. Free sulfide toxicity to microorganisms can be prevented if ferrous iron precipitates the free sulfide. Further, iron sulfide mineral precipitates have been shown to catalyze reductive dechlorination of chlorinated solvents at rates comparable to metallic iron, on a surface area normalized basis. Microcosms performed at high sulfate sites have been showed to both remove free sulfide