2011-03-14_REVISION - M1977493 (48)

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Permit Amendment (AM-06) - Climax Mine CM0000085 Creek systems will generally remain as previously described. • In the Upper Eagle River watershed, however, Robinson Lake is expected to be reclaimed to a fresh water facility, and it, together with Chalk Mountain Reservoir, may no longer be needed by Climax. Therefore, the Chalk Mountain Interceptor could potentially be rerouted to empty directly into Chalk Mountain Reservoir, which overflows directly into Robinson Lake. As shown on Figure AM-06-G-03, it is anticipated that interceptor systems will be constructed around the pit area to reduce the volume of runoff into the pit. G-5.5 Impacted Water Sources The primary sources of impacted water upon closure will not change dramatically from the mineral extraction and production scenario. The amount of fresh water that inadvertently mixes with the impacted waters, however, is expected to be significantly reduced by reclamation thereby reducing the overall volume of water requiring treatment. The primary sources of impacted water will include pit water, water that has infiltrated the underground mine workings, seepage and certain surface runoff from the Storke and camp areas, seepage from the OSFs, 1 Dam, Robinson Dam, 4 Dam, and 5 Dam. Reclamation efforts will attemptto isolate surface runoff from these areas to reduce treatment volumes. The quality of the water seeping from the Storke area, 4 Dam, and Robinson Dam is expected to improve so that they may no longer require treatment prior to discharge into the natural stream systems. G-5.6 Water Treatment Systems Upon closure, the SDP will continue to be used to provide first-stage treatment for some impacted waters. Effluent sludge from the SDP will be pumped into new high-density sludge (HDS) holding cells that are proposed to be constructed on Mayflower TSF between the dam crest and normal water pool. New HDS pipelines and pumping facilities will be required for this task. The treated effluent from the SDP and all other impacted waters will be directed to Mayflower Pond. From there, water will be delivered at a controlled rate to the PDWTP for final treatment and discharge to Tenmile Creek. Depending on the pH of the impacted water stored in Mayflower Pond, pH adjustment may be needed to condition these waters as pretreatment prior to delivery to the PDWTP. The flow capacity of the PDWTP will limit the total discharge capacity of the process water system. This rate is directly related to the storage capacity available in Mayflower Pond. Accurately regulated, the flow rate discharged from Mayflower Pond will promote efficient water treatment within the design capacity of the PDWTP. Sludge generated at the PDWTP will be pumped into the HDS cells located on Mayflower TSF just above the expected normal operating pool of Mayflower Pond. G-5.7 Domestic Water Systems Significant changes to the domestic water systems are expected forthe closure scenario. A certain amount of domestic water will likely be required by the SDP and PDWTP and therefore the system cannot be abandoned entirely. The domestic water demands upon closure are certain to be less than those during mineral production. It is currently envisaged that the Arkansas Well, McNulty Well, and Buffehrs Lake will provide sufficient domestic water upon closure. As a result, these systems will be maintained. Chalk Mountain Reservoir and its appurtenant pump station and pipeline may be removed from the domestic water system. G-6 Groundwater Groundwater in the vicinity of the Climax mine site is generally present within a thin veneer of alluvium and glacial till overlaying the bedrock, and ranges from near ground surface to a few tens of feet below ground surface. Groundwater occurrence within the bedrock is limited to the upper fractured portion of the bedrock units. A hydrogeologic study of the underground workings conducted in 1994 indicated that the bulk permeability of the bedrock is relatively low and that the bedrock is not capable of transporting significant quantities of groundwater. Additionally, it was shown that the presence of the Mosquito Fault provides a hydraulic barrier to lateral flow of groundwater flow in the bedrock. • Exhibit G G-12 May 2010