2011-03-14_REVISION - M1977493 (57)

Home Browse Search

• • Permit Amendment (AM-06) - Climax Mine T-5.4.1 Arkansas River Watershed The mining and crushing/conveying activities that occurred in the Storke Yard area in the past have ceased as the scope and size of operations at Climax have been reduced to mining from the open pit. Closure and reclamation tasks have been completed in the upper Arkansas River watershed. The Arkansas River watershed EPFs are designed to function on a long-term basis, and are not expected to change significantly during final mine closure. The two pumping stations in the Arkansas watershed, per previous discussions, are the critical EPFs in the watershed. Both are active, as they directly contain and control impacted waters. The Storke Wastewater Pump Station has been operational for approximately 30 years without major problems or releases. The 5-Shaft Pump Station, although only operational since 1996, has performed as expected without release of impacted mine water. Prior to startup of the 5-Shaft Pump Station, the underground mine workings were dewatered by other pump systems (i.e. 629), thereby establishing a long history of environmental protection in the Arkansas River watershed. T-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 primary EPFs in the watershed are the Robinson Lake (and dam), the Robinson Lake Pump Station, and the associated seep collection and return system below Robinson Lake. Robinson Lake functions as a process water and seepage containment, storage and return system. The Robinson Lake Pump Station will return process waters directly to the process water tank for the mill. Because the integrity of this collection and return system is essential to production of molybdenum concentrates, close observation of its operation and maintenance of the systems is a priority. The 4 Dam and Robinson Dam seepage collection and pump systems will remain in place and fully functional until such time as seepage from the dam meets water quality standards for this segment of the Eagle River. The 1 Dam EPF has been effective in controlling the release of tailing material from the TSF. The regrading, capping, and reclamation of this dam (Section T-5.2.2) have increased its present and future effectiveness. T-5.4.3 Tenmile Creek Watershed CM0000493 EPFs in the critical Tenmile Creek watershed have been, and continue to be, extremely effective in containing and controlling contaminants and preventing contaminant release into the environment. As the EPFs essentially function in series from the top of the watershed, the effectiveness of the system is increased through the redundancy or secondary containment afforded by this arrangement. Each EPF serves as a protective layer for up-gradient EPFs. However, it must again be emphasized that the upper Tenmile Creek watershed has been significantly impacted by historic placer and lode mining, milling and smelting activities, which peaked in the 1880s. Prior to construction of the Mayflower TSF and the Interceptor System, impacted waters and significant loads of contaminated sediments from these non- Climax historic operations entered Tenmile Creek and were transported downstream. The Climax water treatment and discharge system, which treats large volumes of water, has an exemplary track record. The treated discharge at Outfall 001 has met effluent limitations contained in the permit and has passed Whole Effluent Toxicity (WET) tests. Unlike other more complex and technically complicated water treatment processes, utilizing the first and second stage treatment processes of the SDP and the TSFs for lime precipitation is a simple and effective means of treatment. If a problem were to occur upstream, the decant system on the Mayflower TSF can be managed to increase retention time, thus allowing time ensure treatment process control and discharge. The sulfuric acid tank is 120 percent contained within a series of sumps, and both primary and secondary containment. The EPFs that control and contain the water treatment chemicals, as with the process water and tailing circuit, have a proven track record for effectiveness at the Climax Mine. As discussed in Section T-5.3.2 and in the SPCC/MCP, water treatment chemicals have primary and secondary Exhibit T T-21 May 2010