2024-04-02_REVISION - M1977493 - Laserfiche WebLink

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Permit M-1977-493—Climax Mine Technical Revision 37 (TR-37) block-lined downdrains. The haul road area east of the McNulty OSF will be regraded to remove the roads and blend the area slopes to match adjacent topography. A reclamation cover will be placed after the regrade is completed. It is anticipated that sufficient soil will be salvaged and stockpiled prior to the construction of McNulty and North 40 OSFs for final surface reclamation. Reclamation cover salvaged from the McNulty and North 40 OSF sites will be stockpiled in one of four adjacent locations (Figure F-02, Exhibit F). Estimated reclamation cover quantities (Exhibit I) suggest that a minimum of 24 inches of reclamation cover(subsoil and/or topsoil) can be placed over the overburden rock. Long-term success of the plant community will be directly influenced by the quality and quantities of soil placed. After reclamation cover placement, the lower portion of the OSF (below 11,800 feet) will be seeded with the upland standard seed mixture (Section E-7.1.2). Higher elevation areas will be seeded with the alpine seed mixture (Section E-7.1.3). Figure G-04 (Exhibit G) illustrates the final configuration of water handling facilities and Figure F-04 (Exhibit F) illustrates the anticipated final revegetation. E-11.3 Tailings Storage Facility Reclamation E-11.3.1 Robinson Tailings Storage Facility Robinson TSF reclamation began in the 1980s and is ongoing. The majority of the surface has been capped with overburden rock and covered with biosolids or suitable soil material, and most of that area has been revegetated. The biosolids production area is on the Robinson TSF and will be reclaimed once the existing biosolids are used up. Areas of the TSF that are not bond released will be capped with a minimum of 24 inches of reclamation cover material. Approximately 3% of the total TSF area, not including 200 feet offset from the crest or the bond released areas, will be capped with a minimum of 48 inches of reclamation cover material to promote tree growth. In addition, there are several roads on the surface of the Robinson TSF that are still required for production and reclamation activities. These roads will remain until they are no longer considered necessary. The Robinson TSF decant pool (also known as Robinson Pond) will be filled in with approximately 380,000 cubic yards of fill to remove the pool and allow drainage off the TSF surface to the diversion channels to the east. For the purpose of this closure update, reclamation cover soils will be used for this fill. Future tailings settlement may necessitate maintenance filling of the TSFs in the future. A conceptual configuration of the final reclamation communities is shown in Figure F-05 (Exhibit F) and the final configuration of water handling facilities is shown in Figure G-06 (Exhibit G). E-11.3.2 Tenmile Tailings Storage Facility The Tenmile TSF will be reclaimed when it is no longer required by the operation. As approved for Robinson TSF in TR-13, the Tenmile TSF will be reclaimed with a dry cover. The majority of the surface will be capped, with drainage directed toward the decant structure in the southwest corner of the facility. Areas of the TSF that are not bond released will be capped with a minimum of 24 inches of reclamation cover material. Approximately 3% of the total TSF area, not including 200 feet offset from the crest or the bond released areas, will be capped with a minimum of 48 inches of reclamation cover material to promote tree growth. An emergency open channel spillway will be constructed on the northeast side of the TSF in the event that the decant structure clogs. Excess rock cover or soil material may be used as necessary to achieve TSF stability. A conceptual configuration of the final reclamation communities is shown in Figure F-05 (Exhibit F) and the final configuration of water handling facilities is shown in Figure G-06 (Exhibit G). E-11.3.3 Mayflower Tailings Storage Facility A portion of the Mayflower TSF will be reclaimed when it is no longer needed for production and reclamation operations. However, the southwestern portion of the Mayflower TSF will be used for water treatment as long as it is necessary to provide detention storage for the water treatment system (see Exhibit G: Water Resources). A detention storage area and several sludge cells will remain on the surface of the Mayflower TSF. These areas will receive closure cover once water treatment ceases at the site. The Mayflower TSF will be reclaimed with a dry cover.Areas of the TSF that are not bond released will be capped with a minimum of 24 inches of reclamation cover material. Approximately 3% of the total TSF area, not including 200 feet offset from the crest or the bond released areas, will be capped with a minimum of 48 inches of Exhibit E E-13 March 2024