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Evaluation of Potential Contaminant Migration for Uranium Mining <br />Operations at the SM-18 Mine <br />1.0 Introduction <br />The purpose of this report is to evaluate potential environmental impacts of <br />mining operations at the SM-18 mine located near Uravan, Colorado. Based on SPLP <br />tests on waste-rock samples requested by the Colorado Division of Mines and Geology <br />(DMG), several constituents of concern were identified that exceed water quality <br />standards. As a result, the Colorado Division of Mines and Geology has requested that a <br />contaminant transport evaluation be conducted to consider the potential impacts to <br />groundwater resources from the ore and waste-rock piles. Specifically, DMG requested <br />calculations to determine if the potential contamination is minimized by the effects of <br />dilution and transport prior to reaching a receiving groundwater aquifer or a receiving <br />surface water body. <br />Geoscience Services had been retained by the Cotter Corporation to conduct an <br />analysis of the transport of potential constituents of concern from the uranium mining <br />operation to the groundwater and neazby surface water receptors in order to fulfill the <br />Colorado Division of Mines and Geology request. To accomplish this analysis, a <br />groundwater flow and contaminant transport model was developed to predict the <br />environmental impact of mining operations. The numerical code PORFLOW was <br />selected based on the code's ability to simulate multiphase flow and transport, calculate <br />the effects of sorption, and simulate the decay of radionuclides. For the simulations, a <br />conservative approach was adopted that assumed aworst-case scenazio. Because there is <br />a limited amount of technical data available for the hydraulic and transport parameters of <br />the geologic strata under the site, these parameters were estimated using the best <br />available geotechnical data available from the literature. Since there is commonly a <br />range of values associated with these hydraulic and geochemical pazameters, values that <br />result in the highest transport rates were selected. <br />