2011-03-14_REVISION - M1977493 (62)

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CM0001660 Eagle Park Reservoir A Summary of Water Resource Development and Reclamation of the Oxide Pond, Climax Mine Introduction Eagle Park Reservoir has been the subject of a large scale reclamation and redevelopment project at the Climax Mine. The history of the reservoir has changed since construction in the 1960's from a tailing impoundment to its current use in water storage. The ability to develop water storage for delivery into the Eagle River basin is predicated on the removal of source material (tailing), and the assurance of both dam safety and water quality. The project was initiated during a period of non-production at Climax when water rights were recognized as a long term asset for the property. Through feasibility evaluations, tailing removal, and the implementation of pollution prevention, dam modification, and reclamation programs, the reservoir is now prepared for water storage. Climax No. 4-Dam (a.k.a. Oxide Pond, now Eagle Park Reservoir) is the lowermost water impoundment in the Eagle River basin at the Climax Mine. The impoundment was constructed in two stages from 1964 to 1968 to support the development of a molybdenum oxide ore extraction process. Tailing from the tech-oxide molybdenum recovery system was managed through separate regrind circuits and pre-concentration prior to acid leaching at the Oxide Plant. The tailing material from this process was of a finer gradation and therefore needed to be managed separately from the cyclone deposition on 1-, 2-, and 3-Dams located in the Tenmile Creek drainage. The management applied to the oxide tailing called for impoundment behind the earthen core 4-Dam. Tailing deposition in the impoundment occurred between 1966 and 1969. A limestone milling circuit for limestone delivery was initiated in 1971 and 1972 to neutralize the water for return to the mill. Conceptual Development Citation of the reclamation planning for the Oxide Pond is important to the understanding of the drivers for this project. In 1977, the Climax Mine Reclamation Permit discussed use of the Oxide Pond as a water storage impoundment and an emergency tailing deposition system. Tailing were to be reclaimed in place using a riprap cap followed by agronomic treatments, seeding, and shrub or tree establishment. The reclamation permit was amended in 1989, changing the post-mining land use of the Oxide Pond to water resources. The timetable identified in the 1989 amendment indicated that the water resource development was complete. At the time, the utility of the reservoir was targeted at water delivery, through treatment, into Tenmile Creek. Definition of the methods and requirements needed to develop the reservoir for water delivery into the East Fork of the Eagle River were not specifically outlined. Final