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 Mine development work will include improvements to an existing haul road along Ceresco Ridge. Placement of fill material for this haul road within the Arkansas River watershed will be minimized and storm water runoff from this area will be managed to prevent impacts to the Arkansas River. As described above, and as listed in Table T -3, the sources of potential contamination in the Arkansas River watershed include: • Impacted water from the flooded underground workings; • Run -off and seepage from the Storke Yard; and • Run -off and seepage from road cuts and overburden fill placement for road construction on Ceresco Ridge above the Storke Yard. With the reclamation completed at present, issues related to run -off and seepage have been significantly reduced. There are no designated chemicals stored or utilized within the Arkansas River watershed. T - 5.1.2 Environmental Protection Facilities The following controls are designated EPFs to prevent potential impacts to the Arkansas River Watershed from Climax operations: ■ 5 -Shaft Pump Station (and associated Storke Pipeline); ■ Storke Wastewater Pump Station; and • Ceresco Ridge Haul road Fill Area Runoff Collection System. 5 -Shaft Pump Station and Storke Pipeline: A pumping station installed in 5 -Shaft maintains the water level at an elevation that does not threaten the flow of impacted water to the Arkansas River Valley. Storm water becomes impacted as it passes through the open pit area and collects in the underground mine workings. The quantity of water entering the shaft fluctuates seasonally based on the amount of runoff into the open pit area. Generally, minimum flows occur in the late fall through winter, increase as early as April or May, and peak from mid -June through early August. The level of water in 5 -Shaft must be kept below the apex of the Mosquito Fault to prevent mine water from potentially impacting the Arkansas River. The water level is maintained by pumping water through the Storke Pipeline to the process water circuit in the Tenmile Creek Watershed. As the mining of the open pit advances in depth, the 5 -Shaft Pump Station may become obsolete where water levels will be controlled through other means. Storke Wastewater Pump Station: The Storke Wastewater Pump Station is located just below the Storke Yard and acts as a seepage collection and return system where collected impacted water is pumped to the process water circuit in the Tenmile Creek drainage. Two concrete lined ponds at this EPF serve to collect seepage and storm water /snowmelt run -off from the yard area and return it to the Tailings Distribution House (TDH) where it mixes with mine water prior to treatment. Ceresco Ridge Haul Road Fill Area Runoff Collection System: Depending on the amount of fill needed to improve the existing Ceresco Ridge haul road, some of this material may extend into the Arkansas River watershed, and a runoff collection ditch may be needed below the additional fill placement on Ceresco Ridge. The purpose of the collection ditch, if necessary, will be to intercept potentially impacted runoff from this area and route the water to the camp area or open pit, where it will be sent to the water treatment system (SDP) for treatment. Climax will submit the design for this system to DRMS for review and approval prior to construction. T -5.2 Eagle River Watershed T -5.2.1 Potential Sources of Contamination As listed in Table T -3, the sources of potential contamination in the upper watershed of the East Fork of the Eagle River within the Climax property include: EPP: Version R2 T -18 December 2011