2011-12-15_REVISION - M1977493 (2)

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Technical Revision (TR -18) Climax Molybdenum Company Environmental Protection Plan Permit No. M- 1977 -493 changes in pore pressure conditions in the operational facilities and will identify key piezometric elevations. This information will be submitted to DRMS, along with updated stability evaluations, in an operations and monitoring program for the TSF. 5 Dam Seepwater Collection and Retum System (Mayflower Pump Station): The 5 Dam seepwater collection and return system at the Mayflower pump station is monitored visually. The pump station contains both stand -by pumps and a stand -by generator set should mechanical or power failures occur. Telemetry to the mill is used to monitor the Mayflower Pump Station remotely. T -6 Groundwater Groundwater at hardrock mine sites in Colorado is regulated through the DRMS under authority of Senate Bill 89 -181. The groundwater program at the Climax Mine entailed drilling four monitoring wells and conducting sampling and analysis of those wells. The first two wells (GWM -1 and GWM -2) were completed in 1984 in the Tenmile Creek valley below the Mayflower TSF. The third well, located in the Eagle River watershed (Eagle Valley MW, or EVMW) between the Robinson Dam and Eagle Park Reservoir, was installed in late 1993. Likewise, the fourth well was drilled and completed in late 1993 in the Arkansas River watershed (ARwell) at the southwest corner of the reclaimed Arkansas gravel pit. Groundwater has been monitored in the Eagle River and Arkansas River watersheds since late 1993. These monitoring wells have generally been sampled quarterly, weather and site conditions permitting, in general accordance with the 1995 Groundwater Monitoring Plan submitted as TR -08. Several new monitoring sites were established during the summer of 2011. In addition, Climax will conduct a hydrological characterization prior to the 2012 field season to better assess the location for several additional monitoring sites. Revisions to the monitoring program and the schedule for ongoing groundwater monitoring, as well as information on groundwater quality, are presented in the Water Quality Monitoring Plan included as Appendix T -C. Per Rule 3.1.7(2)(a), the Water Quality Monitoring Plan (Appendix T -C) presents a discussion of the hydrogeologic conditions specific to each of the three drainages at the Climax mine site. T -7 Surface Water In addition to the water information provided in Exhibit G, information relative to surface water containment and control facilities, surface water quality, the Climax treatment and discharge permit, and surface water monitoring and sampling programs have been discussed thoroughly in Section T -5.0 and in the appendices referenced in that section. The CDPS Permit also contains a discussion of the surface water program at Climax. Maps showing water related features are found in the Figures AM- 06 -T -01 and AM- 06 -T -02. As discussed previously, the Climax Mine site lies within the headwater areas of three watersheds — the East Fork of the Arkansas River, the East Fork of the Eagle River, and Tenmile Creek, with most of the mine's water treatment/management activity occurring within the Tenmile Creek drainage area. Discharge to Tenmile Creek occurs in accordance with CDPS Permit No. CO- 0000248. Surface water quality data in the Arkansas River and in the East Fork Eagle River (upstream and downstream of site activities) are available, and are included in the Water Quality Monitoring Plan (Appendix T -C), establishing baseline conditions in these rivers. The Water Quality Monitoring Plan also contains provisions for continued monitoring of surface water in the Arkansas and East Fork Eagle River. The segment of the Arkansas River through and adjacent to the Climax Site is designated by the Water Quality Control Commission (WQCC Regulation 32) as Segment 1 b of the Arkansas River Basin; the mainstem of the East Fork of the Arkansas River located from the source to a point immediately above the confluence above Bird's Eye Gulch. Segment 1b is classified as Aquatic Life Cold 1, Recreation E, and Water Supply. The segment of the East Fork Eagle River adjacent to the Climax Site is designated by the Water Quality Control Commission (WQCC Regulation 33) as Segment 3 of the Eagle River; all tributaries to the Eagle River, including wetlands, from the source to the compressor house bridge at Belden. Segment 3 of the EPP: Version R2 T -34 December 2011