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Climax Molybdenum Company <br /> Permit No.1977-342 Technical Revision (TR-35) <br /> 1. INTRODUCTION <br /> Climax Molybdenum Company owns and operates the Henderson Mill, located in Grand County, Colorado <br /> approximately 22 miles south of Parshall, Colorado northeast of Ute Pass on the western side of the Continental <br /> Divide in the upper Williams Fork River (WFR) valley of the upper Colorado River basin. The mill receives ore <br /> from the underground Henderson Mine operation via conveyor through a 10 mile-long conveyance tunnel and 5 <br /> mile-long overland conveyor. Molybdenite concentrate is extracted from the ore at the mill facilities by crushing <br /> and flotation. The mill complex area facilities include the portal, overland conveyor, ore piles, the primary mill <br /> building and related facilities and infrastructure, and a Tailing Storage Facility (TSF) located northwest of the mill <br /> complex. The Henderson Mill Water Treatment Plant (WTP) project will be constructed within the mill complex, <br /> northeast of the mill building and within the currently permitted affected land boundary. <br /> Operations at the Henderson Mill began in 1976, and the existing permit, Mining and Reclamation Permit M-1977- <br /> 342, was initially approved by the Colorado Mined Land Reclamation Board (Board) in 1977 after passage of the <br /> Colorado Mined Land Reclamation Act (CMLRA). The existing permit remains in effect for the life of the mine as <br /> set forth in CMLRA §§34-32-103(6), 34-32-109 and 34-32-116(7)(q). The permit was most recently amended in <br /> 2020 with the approval of AM-07. In addition, 34 previous Technical Revisions JR) to the Permit have been <br /> approved by the Colorado Division of Reclamation, Mining, and Safety (DRMS) or withdrawn or superseded by <br /> other technical revisions or amendments. <br /> As described in the current Environmental Protection Plan (EPP),submitted and approved as TR-34,the Mill WTP <br /> will be an Environmental Protection Facility (EPF). This TR submittal is intended to provide information regarding <br /> the design of the plant to satisfy the requirements of Rule 7.3 and to obtain Division approval to initiate construction <br /> of the facility. <br /> The mill operates as a zero-discharge facility when in full production. Water used in the mill is conveyed to the <br /> TSF in the tailings slurry and then is recycled back to the mill via the East Branch Reservoir (EBR) for reuse. <br /> However, there are certain scenarios that could result in surplus water being stored within the TSF and/or EBR <br /> which, over certain levels, could result in reduced stability. Potential scenarios include: <br /> • The occurrence of an extreme climatic event out of Henderson's control. <br /> • A potential decrease in production causing a related decrease in the consumptive use of water entrained <br /> in the tailings, resulting ultimately in a net positive water balance for the site. <br /> • Upon closure of the mill, where the long-term treatment of collected, impacted water (e.g., water that <br /> seeps from the TSF, or"seepage water") is anticipated. <br /> The proposed WTP will provide additional safety measures for the TSF and EBR as well as operational flexibility <br /> by enabling surplus water to be treated and discharged. <br /> The information being provided with this TR represent General Arrangement drawings to allow the Division's <br /> review under Rule 7.3. Henderson is working with the State of Colorado Department of Public Health and <br /> Environment (CDPHE) to obtain a renewal of the existing discharge permit that will allow off-site discharge of <br /> treated effluent from the WTP to the Williams Fork River(WFR). The final permit renewal is expected to be issued <br /> in late 2022 or early 2023 with construction beginning after receipt of the final permit renewal (2022-2023). The <br /> WTP is expected to begin operations in 2023 or 2024. <br /> April 2022 <br />