2011-03-01_REVISION - M1977493 (6)

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Mr. Eric Scott Climax Mine - Response to DRMS Adequacy Review Comments Permit M-1977-493; Amendment AM-06 March 1, 2011 Page 12 of 16 From recent experience on the Robinson TSF at the Climax Mine, the analysis of tailing closure at the Henderson Mill (AM-04; Permit # M-1977-342), and the reclamation and closure of the inactive Urad Mine, it is recognized that operating large earth-moving equipment over previously saturated tailing to construct a dry cap can be difficult and may not be viable. In addition, saturated tailing may continue to consolidate and settle for many years after deposition, altering post capping topography and inhibiting proper drainage. Exhibit U/Section (10) Comment 1: Surface Water Control and Containment Facilities Information - Why have the approximately 13 miles of "clear water" diversion ditches that currently exist not been classified as an EPF as described in Section (10)(a)(ii)? It would appear that they are critical to the proper operation of the facility as it currently exists, as well as vital to minimizing the amount of impacted water requiring treatment prior to discharge. Response: As described in Exhibit T Sections T-5.2.1 and T-5.3.1, CIVIC recognizes the importance of the clear water interceptor canal system to the overall water management system, but the clear water interceptors do not meet the definition of an EPF. These systems were constructed in the early 1970s and have not been defined as EPFs, consistent with the approach taken for similar systems at the Henderson Mine. As described in the Hard Rock/Metal Mining • Rule, an EPF is a structure which is identified in the Environmental Protection Plan as designed, constructed and operated for control or containment of designated chemicals, uranium, uranium by-products or other radionuclides, acid mine drainage, or toxic or acid-forming materials that will be exposed or disturbed as a result of mining or reclamation operations. Because the clear water interceptors do not control nor contain designated chemicals, acid mine drainage, or toxic or acid- forming materials, they have not been classified as an EPF. The interceptor system is inspected on a daily basis as part of the comprehensive routine site monitoring activities and maintenance is performed as necessary to ensure the proper functioning of the system. As discussed during the February 4, 2011 meeting with DRMS, CIVIC will work with DRMS to adequately describe these features in a revised EPP to be submitted for DRMS review and approval prior to resuming full- scale mining and milling operations. Exhibit U/Section (10) Comment 2: Have the specifications/processes for the increase in dam height for the Mayflower and Tenmile Dams been certified by a licensed professional engineer? If so, have these designs been reviewed and approved by a qualified independent third party? Response: Design analyses for the Tenmile and Mayflower TSF dam raises have been prepared by a licensed professional engineer (AMEC Earth and Environment). These designs are currently under review by CIVIC and a third party consultant (URS Corporation). Once finalized, an appropriate design submittal will be provided to DRMS to satisfy requirements of Rule 6.5 and 7. Exhibit U/Section (12) Comment: Water Quality Monitoring Plan -The Division understands that a comprehensive Water Quality Monitoring Plan is currently being generated by the Operator and will be submitted under separate cover for Division approval as specified in TR-08. This document