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material or that uranium is not present in the permitted area please provide the rationale explaining that <br />position. <br />Environmental Protection Facilities (EPFs). In Section 6.0 Denison states, "...future EPFs are not planned to <br />be constructed, because neither designated chemicals, nor toxic- or acid-forming materials or acid rock <br />drainage are present at the Sunday Group Mines." <br />DRMS response: Again, it is the Division's position that uranium is a toxic-forming material and that this <br />permit is a DMO. The Division believes that uranium is present, even if it is restricted to traces of ore and <br />low-grade ore that were stored on the pad, on the working surface of the pad, and/or in reworked areas of the <br />pad and loadout where it may be incorporated into the pad material. The pad surface is not lined and the <br />subsurface material is permeable, which allows leachate from the ore to potentially move through the pad. <br />Please state whether there are other areas of the site, based on the justification given above, that should be <br />considered as EPFs and if applicable, a plan for remediation or improvement. <br />Ore storage pad. The Division is not aware of any ore presently stored on the pad nor of any new ore being <br />hauled from the portal, though the permit is approved for such activities. If and when hauling. and <br />stockpiling of ore resumes, the Division assumes that the residence time of the ore stockpile will be only a <br />matter of days (similar to Denison's other permitted operations in this group). Pursuant to Hard Rock/Metals <br />Rule 6.4.20(7) it is appropriate that the ore stockpile areas be considered EPFs. Prior to future stockpiling, <br />Denison must demonstrate that the existing ore stockpile areas provide adequate containment of runoff and <br />leachate of the toxic-forming materials, or perform the construction tasks necessary for the ore pad to <br />provide such containment. Please see the attached "General Ore Pad Construction Criteria." Please confirm <br />that the ore pads have been properly constructed and tested to meet those requirements, or propose a <br />construction and certification plan, with a timeframe. <br />Unsaturated (UNSAT-H) model and percolation estimation. Denison has provided information showing the <br />limited mobility and reduced threat from various minerals in the mined and unmined rock material, based on <br />the geologic characteristics as well as the and climate at the mine. The wettest months are August through <br />October, which suggests that precipitation during those months is delivered via thunderstorms - potentially <br />high intensity events. It is known that plumes can form beneath waste rock facilities in and climates in <br />response to seasonal patterns of such high intensity events. Please address the following: Does the model <br />account for high-intensity, short-duration precipitation events such as thunderstorms? If not, what effect <br />would these have on percolation estimates? <br />Permanent stormwater structures. The Division requires that stormwater runoff originating from the affected <br />areas (pad surfaces and slopes, stockpile areas, and roads) be controlled adequately. The Division considers <br />such runoff and its control during the mining phase (including periods of temporary cessation, if any) to be <br />adequately addressed. However, the EPP states that certain stormwater control structures will be permanent, <br />and remain on the site after final reclamation. The StormwaterManagement Plan (SWMP) prepared for <br />CDPHE-WQCD, and included in this EPP within Attachment F, reiterates the statement that certain Swales <br />and Diversion Ditches will be permanent and remain onsite, though which specific structures are not <br />identified. It is the Division's concern that there may be some such structures onsite that are planned to <br />remain after reclamation (understood to be after monitoring and maintenance by the operator have ceased) <br />that may not be able to continue functioning adequately to control, convey or divert their designed working <br />capacity. The design capacity and the design storm event were not found described in the EPP or in the