2011-08-08_REVISION - M1977493 (33)

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• • • Technical Revision (TR -18) Climax Molybdenum Company Environmental Protection Plan Permit No. M- 1977 -493 T -5.1 Arkansas River Watershed T -5.1.1 Potential Sources of Contamination The upper Arkansas River Watershed contains portions of the Climax site that supported the historic underground mining operations. Prior to closure of the underground mine, the entrance to the underground operation at Climax was through 5 -Shaft and the Storke Portal at the Storke Yard just east of the hairpin turn on Highway 91, in the upper Arkansas River Watershed. When the underground operation was terminated in December 1994, equipment was salvaged and pumping was curtailed allowing the deeper workings to be inundated. Water in contact with sulfide mineralization underground meets the definition of "Acid Mine Drainage" in Rule 1.1 (2), and thus, is a potential source of contamination to the upper Arkansas River Watershed should water levels rise uncontrolled. Storm water becomes impacted as it passes through the open pit area and collects in the underground mine workings. Former underground workings and the open pit are connected to the 5- Shaft located in the Storke Yard area and, as described below, a pumping station installed in 5 -Shaft maintains the water level by pumping water through the Storke Pipeline to the process water circuit in the Tenmile Creek Watershed. The Storke Yard historically incorporated some mine waste rock material for construction fill. The areas of the mine in the upper Arkansas River Watershed have been the focus of major reclamation activities since the late 1980s. Equipment was removed and buildings were demolished in preparation for final reclamation of the Storke Yard in 1995 and beyond. Impacted water from the Storke Yard area is directed to the Storke Wastewater Pump Station, described below. In addition to historic Climax operations, there are other non - Climax, abandoned mined land (AML) features present in the upper Arkansas River Watershed. As part of previous reclamation activities in this area, some impacted water from these AML features is directed to the Storke Wastewater Pump Station. A project to restore a buried segment of the East Fork Arkansas River running along the south side of the Storke Yard was completed in 2008. The area of the Arkansas River to the south - southwest of the Storke Yard was reclaimed in the late 1980s into the early 1990s. This area terminates in the gravel pit at the Climax property line. The East Fork Arkansas River runs through this reclaimed gravel pit before leaving the property and groundwater under the direct influence of surface water in this area is the source of domestic water for the mill as described in Permit Amendment AM -06 Exhibit G — Water Information. Mine development work will include improvements to an existing haul road along Ceresco Ridge. Placement of fill material for this haul road within the Arkansas River watershed will be minimized and storm water runoff from this area will be managed to prevent impacts to the Arkansas River. As described above, and as listed in Table T -3, the sources of potential contamination in the Arkansas River watershed include: • Impacted water from the flooded underground workings; • Run -off and seepage from the Storke Yard; and • Run -off and seepage from road cuts and overburden fill placement for road construction on Ceresco Ridge above the Storke Yard. With the reclamation completed at present, issues related to run -off and seepage have been significantly reduced. There are no designated chemicals stored or utilized within the Arkansas River watershed. T - 5.1.2 Environmental Protection Facilities The following controls are designated EPFs to prevent potential impacts to the Arkansas River Watershed from Climax operations: • 5 -Shaft Pump Station (and associated Storke Pipeline); EPP: Revision R1 T -15 July 2011