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Mr. Marshall Cloud <br /> November 27, 2007 <br /> Page 2 <br /> study ground water flow direction and monitoring post-fracture down-gradient or cross- <br /> gradient effects. The wells are planned to be screened in the most permeable B-zone <br /> lithology, anticipated to be 50 to 53 feet bgs. Two representative soil samples from <br /> local B-zone lithologies will be collected from the monitoring well borings during <br /> installation, and will be used for benchscale testing. Once the monitoring wells are <br /> constructed and developed, approximately six gallons of water for each soil type <br /> encountered will be collected for additional benchscale testing. <br /> The In-situ Chemical Oxidation pilot study will include performance monitoring <br /> consisting of the following: <br /> ■ Collection of ground water samples from MW41 EB, MW312B and MW313B at <br /> three, six, and twelve months following injection of KMnO4 slurry for <br /> measurement of ground water parameters, chemical analysis, and color <br /> observations to monitor post-fracture effects outside the treatment area; <br /> • Completing three additional soil borings (co-located with three original borings) <br /> approximately 12 months after KMnO4 slurry injection to evaluate the vertical <br /> migration of the oxidant from the initial fracture location and estimate diffusion <br /> rates; <br /> • Collecting ground water samples from three CPT locations (co-located with <br /> Phase II CPT locations) to determine contaminant and metal concentrations <br /> approximately 12 months after KMnO4 injections; and <br /> • Performing a slug test 12 months after KMnO4 slurry injections. <br /> DTSC has reviewed the above-mentioned pilot study work plan and has the following <br /> comments: <br /> General Comments <br /> 1. DTSC recommends establishing the natural oxidant demand of the saturated soil <br /> matrix through the analysis of uncontaminated samples rather than samples still <br /> containing contamination during benchscale testing. Testing the uncontaminated <br /> samples will allow the measurement of the soil matrix's natural organic matter, <br /> known for its high oxidant demand, and accounts for approximately 90% of <br /> oxidant consumption. Determining oxidant mass solely through analysis of <br /> matrix samples still containing contamination could potentially overestimate the <br /> amount of oxidant required and subsequently injected into the soil matrix during <br />