2024-05-17_REVISION - M1977493 (4)

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pump systems are shown on the figure. A surface flood spillway will be required for flood protection of Mayflower TSF. This could be the existing Mayflower Tunnel or a new surface spillway channel that would discharge to the east side of the valley into the ESC. Both systems are shown on Figure G-09. The figure shows two Treatment Sludge Cells located on the surface of the TSF in the Clinton Gulch area. The size of the two-cell system is arbitrarily shown on the figure at 34 acres. It is assumed that sludge from the PDWTP would be trucked to the sludge cells, similar to how it is currently done. B. Water Conveyance The East Side Channel would continue along the east side of Mayflower TSF. A turnout to the Mayflower pool is shown for use if the ESC needs to be treated. The East Side Pipeline would discharge into the Mayflower water pool. The existing West Interceptorwould continue to operate to reduce inflow into the process water area on Mayflower TSF. The existing Clinton Canal could continue to operate to convey Clinton Reservoir releases to Tenmile Creek. The existing Mayflower Return System from the PDWTP would be extended to discharge into the Mayflower water pool for use during upset conditions at the PDWTP (same as existing). It is assumed that the natural Mayflower Creek channel would be used to convey ESC flow down the hillside to the Mayflower Canal. It may be necessary to improve the Mayflower Canal to accommodate additional flow from the ESC. C. 5 Dam The downstream face of 5 Dam would be capped and reclaimed (57 acres). A surface water collection channel would convey clean water to the east for discharge into Tenmile Creek. The existing Mayflower seepage collection and pumping system would continue to operate. However, it is assumed that the impacted waterwould be conveyed directly to the PDWTP instead of pumping up to the Mayflower water pool. This would not be done until the PDWTP is converted to 2- stage treatment. D. PDWTP The PDWTP will continue to be required to treat and release impacted water from the process water areas at the site. It is expected that the required treatment capacity in the closure scenario would be less than the current 14,000 gpm. It is assumed that the plant would eventually be converted to 2- stage treatment process to allow for the decommissioning of the SDP. G-3.4 Closure Water Balance Water treatment is expected to be required for an extended period at the Climax Mine after closure and reclamation is complete. The volume of process water requiring treatment will impact ongoing operational costs at the site. The estimates of future water treatment requirements are provided herein for estimating future costs and should be considered approximate. Various details of the reclamation configuration can impact this estimated volume. G-3.4.1 Current Water Treatment Requirement The current process water area that contributes water to the watertreatment system is approximately 5839 acres, as shown on Figure G-1. Precipitation runoff and seepage from this area is collected in the process water system and either consumed on site or treated at the PDWTP and released to Tenmile Creek. The PDWTP effluent is metered and has averaged about 9,341 acre-feet per year from 2014 to 2022 (approximately 5,800 gpm average annual rate). Water within the process water system is consumed through evaporation from water pools and Exhibit G G-14 May 2024