1995-08-11_REVISION - M1977493 (9)

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5.4.1 Arkansas River Watershed The mining and crushing/conveying activities which occurred in the Storke yard area in the past have ceased as the scope and size of operations at Climax have have been reduced to mining from the open pit. Only closure and reclamation tasks remain in the upper Arkansas River watershed. The remaining EPFs are expected to function for the long-term, with final reclamation of the Storke yard and reconstruction of the Arkansas River channel being the last step in this process. The two pumping stations in the Arkansas watershed, as per previous discussions, are the critical EPFs in the watershed. Both are considered active and long-term, as they directly contain and control acidic waters. The Storke wastewater pump station has been operational for approximately 15 years without any major problems or releases. The No. 5 Shaft pump station, although only operational for a short time, has performed as expected without any release of acid mine water. 5.4.2 Eagle River Watershed As with the EPFs throughout the Climax Mine site, those in the upper Eagle River watershed • have been highly effective in containing and controlling the release of potential contaminants during the recent history of the mine. The two most critical EPFs in the watershed are the Eagle Park Reservoir (and dam) and the associated Eagle Park Reservoir seepage collection and pump station. Both of these facilities are located near the property boundary and form the last line of defense should the release of potential contaminants occur upstream. While the Eagle Park Reservoir EPF will be cleaned of contaminated sediment and water for fresh water storage, it still retains the long-term emergency function of containing accidental and unanticipated releases from the Robinson Reservoir and other upstream sources. Likewise, the Eagle Park Reservoir seepage collection and pump station will remain in place and fully functional until such time as seepage from beneath the dam meets water quality standards for this segment of the Eagle River. Following the aforementioned EPFs, the next most important EPF in the upper Eagle River watershed is the Robinson Reservoir and pump station. Although there are conceptual plans to convert Robinson Reservoir into fresh water storage as with the Eagle Park Reservoir, its present function is strictly that of a process water(from the Ten Mile tailing impoundment) and seepage (from the Robinson tailing impoundment via No. 1 Dam) containment and return system. The Robinson pump station returns process and seep waters directly to the process water tanks adjacent to the mill building. Because the integrity of this collection and return system is absolutely essential to production of molybdenum concentrates, it has been well maintained and 30