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Mr. Dustin Czapla <br /> August 24, 2021 <br /> Page 6 <br /> 4.3 Tailings Storage Facility. The Concerned Citizens provide the following specific <br /> comments regarding the Tailings Storage Facility: <br /> The Tailings Storage Facility is a disposal pit where milling waste will be deposited for <br /> eternity. The disposal pit is designed to have a geosynthetic clay liner with a permeability of <br /> 1x10-6 cm/sec and a 45-mil polypropylene liner with a seepage/leak detection system between the <br /> clay liner and the polypropylene. The seepage/leak detection system will cause any liquids that <br /> leak through the polypropylene to flow to a sump,where leakage can be observed,and any leakage <br /> will be pumped back into the disposal pit. (Mining Plat § 4.3 at 4-21.) <br /> DRMS has no regulatory standards for disposal pits such as the one proposed. However, <br /> the Colorado Department of Public Health and Environment, Hazardous Materials and Waste <br /> Management Division, which regulates hazardous and solid waste disposal facilities, has specific <br /> design criteria for landfills, waste impoundments and oil and gas production waste ponds. While <br /> excluded from the RCRA definition of"hazardous waste"by virtue of the mining activity, sodium <br /> cyanide and other chemicals to be used at the Mill are in fact deemed hazardous wastes. The <br /> RCRA mining exclusion makes them no less hazardous to human health and the environment,and <br /> the requirements for disposal facilities receiving those wastes at a mill site should be no less <br /> protective than RCRA requirements. <br /> Hazardous waste regulations require a top liner designed to contain the hazardous <br /> constituents and a composite bottom liner consisting of an upper component designed to contain <br /> the specific waste and a lower component consisting of 3 feet of compacted soil with a hydraulic <br /> conductivity of no more than 1x10-7 cm/sec. 6 CCR 1007-3, §§ 264.221(c), 264.301(c). The solid <br /> waste regulations require a clay liner with a hydraulic conductivity of at least 1x10'7 cm/sec and a <br /> 60-mil polypropylene layer. 6 CCR 1007-2, Part 1 §§ 9.3.1(B) and 17.3.1(A)(2).) The hazardous <br /> waste and solid waste regulations also contain more robust standards for leachate collection and <br /> leak detection than Applicant has proposed. <br /> In addition,Applicant has not adequately evaluated the stability of the disposal pit. DRMS <br /> Rule 6.5 requires an analysis that confirms off-site areas will be safe. 2 CCR 407-1, Rule 6.5(3). <br /> The analysis must include evaluation of the consequences of a failure and the potential for seismic <br /> activity. The Application includes a ten-year-old stability evaluation report (Appendix 22-5), but <br /> cyanide leaching was not part of the plan at that time. Applicant should prepare a new stability <br /> analysis that takes current conditions into account and that includes cyanide and other wastes in <br /> the risk analysis. <br /> Because the proposed disposal pit design falls short of the standards for both hazardous <br /> and solid waste facilities,but will receive highly toxic wastes,the Concerned Citizens request that <br /> the Board deny the Application. If the Board elects to approve the Application, the Concerned <br /> Citizens request that the permit include terms requiring disposal pit design and operations <br /> consistent with the hazardous waste surface impoundment regulations. Applicant also should be <br /> required to undertake a new stability analysis. <br /> BURNS FIGA & WILL <br />