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Permit Amendment (AM-06) - Climax Mine <br />CMC000485 <br />runoff into the open pit area. Generally, minimum flows occur in the late fall through winter, increase as <br />early as April or May, and peak from mid-June through early August. The level of water in 5-Shaft must be <br />kept below the apex of the Mosquito Fault to prevent mine water from potentially impacting the Arkansas <br />River. The water level is maintained by pumping water through the Storke Pipeline to the process water <br />circuit in the Tenmile Creek watershed. As the mining of the open pit advances in depth, the 5-Shaft <br />Pump Station will become obsolete and water levels will be controlled through other means. <br />Storke Wastewater Pump Station: The Storke Wastewater Pump Station is located just below the Storke <br />Yard and acts as a seepage collection and return system where collected impacted water is pumped to <br />the process water circuit in the Tenmile Creek drainage. Two concrete lined ponds at this EPF serve to <br />collect seepage and stormwater/snowmelt run-off from the yard area and return it to the TDH where it <br />mixes with mine water prior to treatment. <br />Ceresco Seepage Collection System: Construction of a new seepage collection system is contemplated <br />below the proposed fill placement on Ceresco Ridge to intercept and collect impacted water from this <br />area. <br />T-5.2 Eagle River Watershed <br />T-5.2.1 Potential Sources of Contamination <br />As listed in Table T-3, the sources of potential contamination in the upper watershed of the East Fork of <br />the Eagle River within the Climax property include: <br />¦ 4 Dam seepage; <br />¦ Robinson Dam seepage <br />¦ Tenmile Tunnel and 1 Dam seepage; <br />¦ Robinson Lake (aka: Robinson Reservoir); and <br />¦ A portion of the Robinson TSF. <br />Drainage of contaminants from Robinson TSF would first enter Robinson Lake. Minor reieases from <br />Robinson Lake could be contained in the seepage collection pond located just downstream of Robinson <br />Dam. A major release from Robinson Lake or overflow of the seepwater collection pond would enter <br />Eagle Park Reservoir before impacting the Eagle River and its environs below the Climax boundary. <br />The Oxide Pond (Eagle Park Reservoir) was first constructed in 1965 to impound tailing material from the <br />oxide ore processing facility at Climax. Oxide ore processing was discontinued in 1968. The tailing <br />material and sediments in this TSF were acidic and contained elevated levels of metals. Seepwater <br />emanating from the toe of the dam likewise was acidic (Appendix G, original 1995 EPP). <br />In 1993, a project was initiated to convert Eagle Park Reservoir to a fresh water impoundment to allow <br />Climax to sell the storage facility. Such a conversion of this impoundment required draining of impacted <br />water, removal of tailing material and contaminated sediments, and prevention of Robinson Lake <br />seepage from entering the impoundment. This project was completed in 1997. Impacted media (water, <br />tailing, sediment, and soils) were removed to the Tenmile TSF and 2 Dam during the course of this <br />project. In addition, a concrete cut-off wall was installed below Robinson Dam to prevent seepage from <br />entering Eagle Park Reservoir. Eagle Park Reservoir was released from DRMS financial warranty and <br />was sold to a consortium of downstream users in 1998. Eagle Park Reservoir is no longer considered an <br />EPF for Climax. <br />Robinson Lake functions as the primary process water storage facility in the system and collects <br />seepwater and toe drain discharge from 1 Dam. Robinson Lake also stores process water collected from <br />the Tenmile and Mayflower TSFs through the Tenmile Tunnel, the Mayflower barge system (during Phase <br />II Deposition) and, as needed, from the extension from the Supply Canals Nos. 1 and 2 (Figure AM-06-T- <br />01). Water collected from the Tenmile TSF is decanted through the Tenmile Decant to the Tenmile <br />Tunnel. The reservoir contains industrial process water, TSF seepwater, and sediments. <br />Exhibit T T-13 May 2010