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Mu Dustin Czapla <br />Page 7 of 8 <br />aProposed Seed Mix 3: Gunnison District Seed Mix — 2D12 <br />Mixture/Variety Percent of Mixture <br />a _ PLS basis <br />Slender Wheat San Luis 60 <br />Barley Triumph 20 <br />Western Wheat, Amba 20 <br />u The proposed seed mixes are specified on a Pure Live Seed (PLS basis) and would be <br />applied at a rate of 50 pounds per acre total seed. <br />Summary <br />An Integral component to establishing a practical, technically achievable, and <br />sustainable LPL is the development of alternatives for uranium load reduction at this <br />high elevation mine site with limited year-round access. Pilot testing in 2015 and 2016 <br />was successful at treating uranium in the underground mine workings and near the toe <br />of the Indian Rock Dump, including desired attenuation of the injected phosphate. The <br />success of these tests was based on observed uranium removal and phosphate <br />attenuation within injection zones and immediately downgradient. This magnitude of <br />treatment was appropriate to the scale of the tests, which were intentionally small in <br />scale to avoid unintended consequences with treatment residuals. However, achieving <br />meaningful load reductions in surface water will require substantial Increases in the <br />scale of operations. The primary goal of the 2017 Meld activities is to achieve this <br />measurable uranium load reduction in downgradient surface water, based on a better <br />understanding of the behavior and management of residual phosphate gained In <br />previous pilot tests. Based on this goal, expansion of the pilot -systems within the <br />underground mine workings and Indian Rock Dump using larger -scale phosphate -based <br />Infections is proposed, with a treatment residual management program in place to <br />actively control residual phosphate concentrations prior to discharge at SW -33 If <br />needed. In addition, scale up of the ETCs below the Tie Camp Rock Dump is also <br />proposed to achieve and sustain uranium load reduction while the injection -based <br />source control strategies are being implemented. In addition, augmentation of the <br />Dapproved seed mix for establishment of vegetation is outlined above as part of the <br />Technical Revision. If you have any questions or require further information regarding <br />this submittal, please contact me at (416) 307-5163. <br />aSincerely, Dale Davis behalf of Holton Bums <br />Holton Bums <br />Homestake Mining Company <br />Director of Closure, Water Treatment & Uranium <br />Homestake M rkq Company -:- PO Sox 40. Sargents, Colorado 81240 <br />