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Mr. Eric Scott <br />Climax Mine - Response to DRMS Adequacy Review Comments <br />• Permit M-1977-493; Amendment AM-06 <br />March 1, 2011 <br />Page 10 of 16 <br />Exhibit U/Section (5)(b) Comment: Based on the best information available at the time of <br />submittal of the EPP, specify the expected concentrations, process solution volumes and fate of <br />designated chemicals to be used in the existing and proposed extractive metallurgical processes <br />at the mine, and/or mill site if applicable. Please also commit to notification of the Division if <br />significant changes will be made to this information, such as the inclusion of cyanide to the milling <br />process. <br />Response: Additional information has been compiled since the submittal of the AM-06 <br />amendment application regarding the storage, use and handling of designated chemicals to be <br />used in the extractive metallurgical process. The EPP will be updated as indicated in the <br />response to Exhibit U/Section (2). Available information is attached to this response letter for <br />reference. This revised EPP shall serve to more clearly define the reagent storage area within the <br />Concentrator (Mill) Building as an EPF, superseding the information provided as part of TR-14 with <br />regard to the Mill Building. Climax will notify the Division if any significant changes are made to <br />the list of designated chemicals to be used or if further changes are made regarding the storage, <br />use and handling of any of the designated chemicals as designs for the concentrator facility are <br />finalized. <br />• Exhibit U/Section (6) Comment: Designated Chemical(s) and Material(s) Handling - Please state <br />how the overburden material handling to be employed during operations will minimize the <br />generation and impact of acid drainage as well as the volume of water requiring treatment during <br />and after mining (material segregation, liners, capping, etc). How will acid drainage from the waste <br />rock dumps be minimized, managed and collected (leachate capture system)? <br />Response: The scheduling/sequencing of overburden placement is currently being performed as <br />part of ongoing mine plan evaluations. As overburden material is placed as part of ongoing <br />operations, CMC will continually look for and identify opportunities to manage overburden <br />materials to minimize acid rock drainage and the volume of water requiring treatment. Techniques <br />can include, but may not be limited to, material segregation (based on acid generating potential), <br />upgradient diversion of unimpacted water, and CMC's election to implement concurrent <br />reclamation to minimize future acid drainage and the quantity of water requiring treatment. <br />Concurrent reclamation of OSFs is described in Exhibit E. As required under Rule 6.4.21(6), <br />appropriate EPFs have been identified for the capture and treatment of acid mine drainage, within <br />the overall site-wide water management system. <br />The locations of OSFs have been developed with consideration of existing conditions as well as <br />overall technical and economic feasibility. As described in Exhibit D, overburden placement will <br />consist of additional placement in the area of existing E and F dumps as well as the existing <br />McNulty OSF. Seepage collection and run-off control facilities, identified as EPFs in the EPP, at <br />these locations will be modified to enhance the collection of water requiring treatment and <br />minimize the impact of potential acid drainage associated with these facilities. Designs for these <br />EPFs will be submitted prior to the initiation of construction in accordance with Rule 7.3.