2018-08-22_REVISION - M1977493A - Laserfiche WebLink

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Technical Revision (TR-28) Climax Molybdenum Company Environmental Protection Plan Permit No. M-1977-493 ■ 5 Dam Seepwater Collection and Return System; ■ Containment for Designated Chemicals for Concentrate Production; ■ OSF Water Management Controls; ■ SDP and PDWTP; ■ Containment for Water Treatment Chemicals ■ East and West Interceptor Systems; and ■ Pit Dewatering System TDL: Tailing delivery and deposition for mine production will utilize the Tenmile and Mayflower TSFs. As presented in TR-14, a 36-inch diameter high-density polyethylene (HDPE) TDL was placed from the mill discharge sump to the Tenmile TSF. The TDL generally follows the alignment of the existing ETDL. The existing 42-inch diameter reinforced concrete pipe (RCP) TDL from the SDP to the Mayflower TSF was rehabilitated, and portions of the TDL were replaced with HDPE to convey tailing beyond the Tenmile TSF to the Mayflower TSF. The TDL is further described in TR-20 and TR-23. TR-23 also describes containment measures included in the design of the TDL in the event of releases from the pipeline and associated drop structures. ETDL: The ETDL conveys impacted water sources to the SDP and serves as an emergency tailing conveyance line should the main delivery line from the Mill to the first discharge point have to be taken out of service for a short period. This line is constructed of 36-inch and 42-inch RCP that isolates the impacted water from the environment until it is delivered to the SDP or deposited in one of the TSFs. East Side Channel: As described in Exhibit G of AM-06, the Robinson Section of the East Side Channel conveys water from the Robinson Pond water pool and areas tributary to the Robinson Pond through the 2 Dam Spillway to Tenmile TSF. Upstream of Robinson Pond, the unimproved portions of the East Side Channel extend along the eastern boundary of Robinson TSF, under the multi-plate culvert beneath Highway 91, along the border of the North 40 OSF that parallels the ETDL/TDL, up to the area of the sanitary wastewater treatment building. This channel collects impacted seepage and run-off from the Camp/Mill area and provides secondary containment for the TDL and ETDL pipelines. Like the ETDL, the East Side Channel conveys the impacted water to the Climax water treatment system. Robinson TSF and 2 Dam: As discussed in Section T-5.2.1, the Robinson TSF encompasses approximately 650 acres. 1 Dam and a small portion of the southern part of this TSF are located in the upper Eagle River Watershed and are discussed in Section T-5.2. The remainder of the TSF and 2 Dam are within the Tenmile Creek Watershed. The Robinson TSF contains mill tailing material. As discussed in Section T-5.2.1, tailing material from the Climax mill circuit is recognized as potentially acid producing. The Robinson TSF has been decommissioned and, as noted previously, is in the final stages of reclamation. However, even when reclaimed, Robinson TSF remains both a potential source of contamination and an important EPF. Tenmile TSF and 3 Dam: The Tenmile TSF, including 3 Dam, currently encompasses approximately 620 acres and is located adjacent to and just downstream of the Robinson TSF. Once Tenmile TSF has reached its planned capacity of tailing material, it will encompass approximately 650 acres. The Tenmile TSF was constructed in the 1950s and contains tailing material that, as discussed previously, is considered acid producing. Operations at Climax are utilizing the Tenmile TSF for tailing disposal and water management. Approximately 5 million tons of additional tailing may be deposited in the Tenmile TSF. Mill tailing in slurry form is delivered to the TSF by the TDL. Clarified water is removed from the TSF through a decant system at Tenmile Decant via the Tenmile Tunnel (to the Robinson Lake or Mayflower TSF as discussed in Section T-5.2.1). A water pool is maintained at the upstream end of the Tenmile TSF for process water storage, storm water management, and as the first stage in the water treatment EPP: Version R4 T-27 August 2018