1998-02-25_HYDROLOGY - M1977493 - Laserfiche WebLink

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WIL 1 (_7� �_ qi%-zz�-1 1� I �_ (I" c-%-/J<, M -4 F044 Mined Land Reclamad 11111111111111111 III in, Year 2000 Awards - 999 Mine Name: Climax Mine Operator: Climax Molybdenum Company Permit No.: M-1977-493 Nominator: Allen Sorenson, Division of Minerals and Geology Summary of Nomination: The Climax Mine is a molybdenum mining and milling operation located 13 miles north of Leadville, Colorado at the summit of Fremont Pass(11,318 ft.). The Climax Molybdenum Company was formed in 1916 and production of molybdenum concentrates initiated at Climax in 1918. By 1980,the Climax Mine and Mill were processing from 45,000 to 50,000 tons of ore per day with a total tonnage production over the mine's history to that date of approximately 360 million tons. Beginning in 1982,the world molybdenum market went into a rapid decline. Production at Climax was curtailed during the early to mid-1980s and since that time Climax has operated only sporadically. The Climax Mine is located within a 14,000 acre block of private land that encompasses the headwaters of Tenmile Creek in Summit County,the Eagle River in Eagle County,and the Arkansas River in Lake County. Mine facilities include water storage and delivery systems with trans-basin conveyance capability to serve both molybdenum processing needs and the management of water allocations in three major Colorado drainages. In 1993,these facilities included the Oxide Tailing Pond located at the headwaters of the East Fork of the Eagle River. The majority of the ore body at Climax is molybdenum disulfide or molybdenite. The beneficiation of molybdenite by grinding and froth flotation is well understood. In the 1960s,Climax explored the potential to recover molybdenum from the oxide molybdenum zone(ilsemannite)surrounding the central molybdenite ore body. This culminated with the construction of the Molyoxide Plant and the Oxide Pond,the latter to store tailing produced from the concentration of oxidized ore. The Molyoxide Plant operated from July of 1966 to September of 1968 when processing of oxide ore was discontinued due to the Molyoxide Plant's interruption of efficiencies in the much larger and highly profitable sulfide milling circuit. And also because of the potential for health and environmental liabilities that were foreseen in the Molyoxide Plant, which used sulfur dioxide,sulfuric acid,and gaseous ammonia. During the two years of operation,more than one million cubic yards of tailing were deposited in the Oxide Pond behind a zoned earthen embankment constructed in two stages from 1964 to 1968. These tailing were highly acidified as a result of the acid leaching process used in the Molyoxide plant. A limestone milling circuit was initiated in 1971 and 1972 to neutralize Oxide Pond water for use in the mill. Interceptor canals were employed to divert fresh water around the Oxide Pond and into the Eagle River. With the interceptor system in operation,Climax still had to pump an average of 300 acre-feet of water per year from the Oxide Pond to the Tenmile Creek drainage for water treatment. A seep water cutoff,collection,and pump back system was installed below the dam to prevent seepage of contaminated water into the Eagle River. In 1989 the Climax Mine reclamation permit was amended and the post mining land use designated for the Oxide Pond was changed to developed water resources. That same year Climax commenced feasibility evaluations of the mine's water rights and the overall water storage and delivery capabilities that the mine infrastructure provided. In 1993 an agreement was forged with Vail Associates to complete tailing removal and reclamation of the Oxide Pond to a fresh water reservoir, now known as Eagle Park Reservoir. The location of the reservoir on private land at the head of the Eagle River is ideal for replenishment of water used for ski area snowmaking and by an influx of tourists during winter low flow months. In November of 1993,Climax submitted a technical revision to their reclamation permit to include a description of the initial tailing removal project using engineered hydraulic monitoring and slurry pumping. The Oxide Pond tailing were relocated to the Tenmile Tailing Pond. High pressure water at 300-400 psi was used to suspend solids and the slurry was pumped overland through a 14 inch pipeline using a series of booster pump stations. The tailing relocation by this method commenced in June 1994 and was suspended in October 1994. An addendum to the tailing relocation technical revision was provided in April 1995. It seems the reslurry of the tailing proved untenable due to high plasticity of the material, and relocation using truck and shovel was proposed. The truck and shovel operation commenced in April 1995 and was completed in October 1996. During excavation,the material behaved as a heavy liquid,requiring short