2015-08-18_PERMIT FILE - C1982056A (3)

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Wolf Creek Reserve. A contractor (CH2MHill) has been selected, and is proceeding with a feasibility evaluation for the proposed treatment system. The proposed pipelines are being permitted at this time to allow construction during the limited 2015 construction field season, so that they will be available to meet the anticipated future long-term, full-scale dewatering requirements, but also to handle very limited initial dewatering and transfer of those limited flows to the existing mine water handling system (6MN Reservoir and 10 -Right Pipeline, as noted). From the 10 -Right Pipeline, the water can be moved through the existing system to the Fish Creek Water Treatment Facility (currently idle), the 18 -Left Pipeline and Borehole (existing — which would allow transfer of water to sealed and abandoned mine workings in the Western Mining District), the mine facilities area for use in the existing Washplant, or the existing transfer pipeline to the Barricade Chamber (routes water back underground for mine use). TC currently handles mine dewatering flows within the existing system, the current system is operated at levels which provide a significant margin between actual and design capacities, and any dewatering inputs to the system from the Wolf Creek Reserve would be limited by existing system capacity. Currently, TC's comprehensive mine water handling and recycling program balances mine water inputs with use so that there is negligible discharge to area streams (other than surface runoff which is routed through the existing drainage and sediment control system), and any discharge which does occur complies with applicable CDPS permit effluent limitations. Any flows from the initial mine dewatering would be limited by the capacity of the existing mine water handling system, with some flexibility to handle any excess water by routing it through the existing system to sealed and abandoned mine workings in the Western Mining District, consistent with current practice. It should be noted that the pipeline extension which would serve the potential future passive treatment system would be constructed, but would not be activated (shut-off valve at 6MN Reservoir) until such time as required permit approvals are obtained and construction of the passive treatment system is completed. Protection of the hydrologic balance and probable hydrologic consequences for the existing mine water handling system are addressed by the descriptive text in Section 2.05.6(3) (pages 2.05-127.1 through 2.05-167). Given that construction and use of the proposed pipelines is simply another connection to the existing system, would operate within the capacity limits and constraints of the existing system, and would not result in any significant changes or increased potential hydrologic impacts, additional plans and analysis are not necessary at this time. While TC discusses reclamation of the proposed disturbance in the revised pages submitted with MR - 288, TC did not revise the reclamation plan in Section 2.05.4 of the permit. Please submit appropriate revised pages to the reclamation plan to account for the additional disturbance. Response: Reclamation for the proposed 5MN Pipelines is discussed (as noted above) on page 2.05- 45.27, and is addressed by the Section 2.05.4 discussion of "Drillhole or Well Plugging and Sealing, and Well and Pipeline Reclamation and Abandonment" on pages 2.05-106.2 and 109.3 (MR10-249).