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Response to DRMS Comments <br />Environmental Protection Plan, <br />Denison Van 4 Mine <br />chemicals, nor toxic- or acid-forming materials or acid rock drainage are <br />present at the Van 4 Mines. <br />DRMS response: Again, it is the Division's position that uranium is a toxic- <br />forming material and that this permit is a DMO. The Division believes that <br />uranium is present, even if it is restricted to traces of ore and low-grade ore that <br />were stored on the pad or handled on the working surface of the staging area <br />pad and ore bins where it may be incorporated into the pad material. That <br />area's surface is not lined and the subsurface material is permeable, which <br />allows leachate from the ore to potentially migrate into the ground. Please state <br />whether there are other areas of the site, based on the justification given above, <br />that should be considered as EPFs and if applicable, a plan for remediation or <br />improvement. <br />Response Regarding the DMO status of the Van 4 Mine and the evaluation of <br />"toxic-forming", please see Response to Comment 1. The state's <br />regulatory mechanism for protection of the environment at DMOs is the <br />identification and management of mine site environmental protection <br />facilities (EPF). The EPP has been revised to designate an ore storage pad <br />at the Van 4 Mine as an EPF in order to implement best management <br />practices. The pad will be designed and constructed using berms and a <br />polyvinyl (PVC) geomembrane liner, or equivalent, to contain storm <br />water in contact with ore material and divert storm water run-on around <br />the pad area. <br />Comment 3 Ore storage pad. The Division is not aware of any ore presently stored on the <br />pad or in the ore bins, nor of any new ore being mined, though the permit is <br />approved for such activities when mining resumes. If an when mining and <br />stockpiling of ore resumes, the Division assumes that the residence time of the <br />stockpiled ore will be only a matter of days. Pursuant to Hard Rock/Metals Rule <br />64.20(7) it is appropriate that the ore stockpile areas be considered EPFs. <br />Prior to future stockpiling, Denison must demonstrate that the existing ore <br />stockpile areas provide adequate containment of runoff and leachate of the toxic- <br />forming materials, or perform the construction tasks necessary for the ore pad to <br />provide such containment. Please see the attached "General Ore Pad <br />Construction Criteria. " Please demonstrate that the ore pads have been <br />properly constructed and tested to meet those requirements, or propose a <br />construction and certification plan, with a timeframe. <br />Response Please see Response to Comment 2. Denison will design and construct an <br />ore storage pad with a PVC geomembrane liner. Production and storage <br />of ore is not currently being conducted at the Van 4 Mine. Prior to <br />resuming these operations, Denison will construct ore pad compliant <br />with DRMS' "General Ore Pad Construction Criteria." <br />Comment 4 Unsaturated (UNSAT-H) model and percolation estimation. Denison has <br />provided information showing the limited mobility and reduced threat from <br />various minerals in the mined and unmined rock material, based on the geologic <br />characteristics as well as the and climate at the mine. The wettest months are <br />DRMS RTC Van4 Mine EPP.doc 5