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16. Underground tailings disposal does not seem like a reasonable single method of tailings <br />management and its feasibility is unknown. The text states "This conclusion and <br />proposed plan for disposal of the tailings will be evaluated during the milling <br />optimization phase during start-up for compliance with performance standards of the <br />Act, and the technical feasibility and economic reasonableness of the plan." <br />17. Per the applicants description, only 2 percent of excavated materials will be removed off <br />site, and the excavated rock may be 10 to 15 percent greater in volume than the in -situ <br />condition. There is no mention of the available volume of underground storage for <br />contaminated tailings, nor how excavated rock and contaminated tailings will be <br />transferred to underground storage. Considering that contaminated tailings are to be <br />stored for perpetuity the applicant should propose an alternate storage method and <br />provide design and storm water management details for review and consideration. <br />18. How will new mining operations (blasting and excavation) affect hydraulics in existing <br />mine tunnels and in those used for storage of contaminated tailings? <br />19. The application text says there is no pathway from groundwater beneath permit area to <br />groundwater receptors this is inconsistent with the reference to a previous section that <br />says extent of rock fractures has not been determined. <br />20. The mine (No.1 Idaho Adit) will discharge directly to surface water tributary to the La <br />Plata River, and according to the text may contain elevated concentrations of arsenic <br />and aluminum. The text also says there is no planned water treatment. How does the <br />applicant intend to ensure discharge water meets aquatic fife standards? <br />21. Discharge from the No.1 Idaho Adit is assumed to be continuous however compliance <br />sampling will occur quarterly which will be inadequate in the event of contamination. <br />County review of the Idaho & Mayday Mine and Mill Complex Class 2 permit should consider <br />the Agency Comments provided by the Lake Durango Water Authority. The Authority Board of <br />Directors remains opposed to La Plata County approval of the Class 2 Permit in addition to our <br />opposition to CDRMS approving the 112D Permit due to the applicants past history of permit <br />violations, proximity of the mine operations to the raw water supply for the Authority and the <br />potential impacts mining operations would have on the safety and quality of water delivered to <br />Lake Durango Reservoir until the concerns listed in the Authority Agency Comments have been <br />addressed. <br />Thank you for your consideration of these issues. <br />Sincerely, <br />Ward Holmes <br />President <br />Cc: Wallace H. Erickson <br />