Colorado Division of Reclamation, Mining & Safety Idarado Natural Resource Damage Remediation Project CDRMS Office Locations Denver Grand Junction Telluride I NTRODUCTION The Idarado Mine is located between the Town of Telluride and the City of Ouray in San Miguel and Ouray counties, respectively. In 1983, the Colorado Department of Public Health and Environment (CDPHE) filed suit against the Idarado Mining Company for natural resource damages under CERCLA (Superfund). The major human health concern is possible exposure to heavy metals in the tailings, specifically lead and cadmium. Human contact with tailings is minimal. The main impact to the aquatic system is from zinc and changes in pH. The state was involved in either court activities or negotiations with the company until July 1992 when a negotiated remedy was finalized in federal court. The remediation involved stabilizing and revegetating the 11 large tailings piles, diverting surface runoff around mine wastes and rerouting internal mine waters away from highly mineralized regions in the underground workings. The majority of the work is completed; additional remediation is being conducted on Red Mountain to continue to improve the water quality in Red Mountain Creek. Negotiations are underway with the Town of Telluride to remediate tailings on its land at Society Turn. The cleanup was implemented by Idarado at their expense. The total cost for this work is approximately 30 million dollars. Mine Remediation Two hundred (200) acres of mill tailings were remediated by reducing slopes to 3H:1V, grading the surface to drain away from the slopes, construction of runoff ditches, and direct revegetation. Direct revegetation involved incorporating soil amendments directly into the tailings: a minimum of 30 tons per acre of limestone, to ameliorate any acid generating potential; and 40 dry tons of cow manure and 20 tons of hay/straw per acre. The amended tailings were seeded with grass and forbs; 383 pounds of N-P-K fertilizer per acre was applied, followed by 2 tons per acre straw/hay mulch. The tailings were fertilized the first 2 years and irrigated the first 5 years after seeding. Concrete channels were constructed on top of the tailings to convey runoff from a 500-year storm event. Mines in the high country were bulk headed to direct flow to 3 mine adits. Mine drainage is infiltrated into the ground via ditches, perforated pipelines, and lagoons. Treatment using Iron Rich Material (IRM) is being planned for the Treasury Tunnel Mine drainage in Red Mountain Creek. Thirty concrete channels were constructed around waste rock piles in the high country to convey runoff from 100-year storm events. Eight stream channels were remediated to minimize contact with mine waste; surface water was diverted to reduce inflow in underground mine workings at five locations. PARTNERSHIPS Remediation of tailings on third party property: remediation of Society Turn Tailings into a ball field and parking lot, now owned by Lawson Hill Community. Negotiations with the Town of Telluride to remediate Society Turn tailings on the San Miguel Valley floor. Remediation of twelve mines on Red Mountain owned by others. CDPHE/DRMS Agreement creating Project Manager job sharing opportunity between agencies. MEASURES OF SUCCESS - PERFORMANCE OBJECTIVES Tailings (Minimize Erosion via Revegetation) Live vegetative cover on top surface and slopes is > 60% Total vegetative cover on top is > 80%; slopes is > 70%. Water Quality (Reduce Zn Concentrations by 50%) San Miguel River : annual avg of 52 weekly samples total Zn <.336 ppm; dissolved Zn <.276 ppm. Red Mountain Creek: dissolved Zn < 1.5 ppm from August-October. PROJECT MANAGER: Camille Price

Colorado Division of Reclamation, Mining & Safety Today Operation and Monitoring Plan (Post CD & RAP) Red Mtn Evaluation Report Red Mtn Performance Objectives Not Met Red Mtn Performance Objective Methodology Town of Telluride Purchases Valley Floor Society Turn Tailings #1 Agreement State and Idarado Telecam ST 2&3, Telluride High Country Telecam ST 2&3 Non Idarado Red Mtn Portals; RMT 2; TT 5-6; UG Mine RMT 4 Red Mtn Portals; Red Mtn Buried Tailings; TT 1-4 Telluride Mine Portals Consent Decree Signed - RAP Litigation; Remedial Investigation; Feasibility Study; Remedy Negotiated Telluride Blood Lead Testing Liaison Committee Construction Phase Monthly Water Quality Monitoring Revegetation Monitoring Natural Resource Damage Fund Proj. Solicitation San Miguel River Compliance Monitoring Society Turn Access Agreement Idarado Consent Decree Chronology Red Mtn. Additional Remediation Society Turn Tailings No. 1 Remediation Red Mtn Creek Water Quality Compliance Monitoring San Miguel Post RAP Monitoring

Colorado Division of Reclamation, Mining & Safety Telluride Tailings 1-4 Remediation Before & After

Colorado Division of Reclamation, Mining & Safety