1995-08-11_REVISION - M1977493 (9)

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. forming materials..." EPFs as defined are present and operational at the Climax Mine site. Because of Climax's unique geographic position affecting both sides of the Continental Divide and three distinct and major watersheds, the following discussion of EPFs and controls is organized by watershed. This relationship is clarified in Table 2. Within the three watersheds, defined EPFs involve (in no particular order): 1) control of run-off which contacts potentially contaminated material; 2) the process water circuit which includes the tailing impoundments and seep water control systems; 3) mine water drainage and control systems; 4) designated chemicals used in the milling process; 5) dust suppression systems; and 6) the water treatment and discharge system including designated chemicals used therein. Specific details such as impacted acreages, etc. of specific areas are found in the Mining and Reclamation Permit, Technical Revisions, and Amendments. The EPFs discussed throughout this EPP are shown on Figures 2 and 3. 5.1 Arkansas River Watershed 5.1.1 Potential Sources of Contamination The upper Arkansas River watershed contains those portions of the Climax site which supported the historic underground mining operations. The primary area of potential impact is the Storke • yard just east of the hairpin turn on Highway 91. This area has been the focus of major closure and reclamation activity since 1993. In 1994, equipment was removed and buildings were demolished in preparation for final reclamation activities in this area in 1995 and beyond. 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 Arkansas River runs through this reclaimed gravel pit before leaving the property. There are four (4) sources of potential contamination to this portion of the Arkansas River watershed: 1) Acidic water from the flooded underground workings; 2) Run-off and seepage from the Storke yard; 3) Catastrophic failure of the two industrial process water tanks located adjacent to the mill complex; and 4) Run-off from road cuts on Ceresco Ridge above the Storke yard. Prior to closure, the entrance to the underground operation at Climax was through the No. 5 Shaft and the Storke Portal at the Storke yard. When the underground operation was terminated in December 1994, equipment was salvaged and the workings were allowed to flood naturally. 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 and overtop the No. 5 Shaft. The Storke yard historically incorporated some mine waste rock material for construction fill. 14