Colorado Division
of Reclamation,
Mining & Safety
Idarado Natural Resource Damage Remediation Project
INTRODUCTION
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
CDRMS Office Locations
Denver
303-866-3567
Grand Junction
970-241-0336
Telluride
970-728-5487
Colorado Division
of Reclamation,
Mining & Safety
Telluride
Mine
Portals
Consent
Decree
Signed - RAP
Red Mtn
Portals;
Red Mtn
Buried
Tailings;
TT 1-4
Litigation;
Remedial
Investigation;
Feasibility
Study; Remedy
Negotiated
1983
Idarado Consent Decree
Red Mtn
Chronology
Performance
Non Idarado Red Mtn
Objective
Methodology
Portals; RMT 2; TT 5-6;
UG Mine
Red Mtn
Performance
Objectives Not Met
Telecam ST 2&3
Telecam ST 2&3,
Telluride High
Country
Society Turn
Tailings #1
Agreement
State and
Idarado
RMT
4
1991
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
San Miguel Post RAP Monitoring
Red Mtn Creek Water Quality Compliance
Monitoring
Red Mtn. Additional Remediation
Society Turn Access Agreement
Society Turn Tailings No. 1 Remediation
1997
2000
2003
2006
Red Mtn Evaluation
Report
Town of
Telluride
Purchases
Valley
Floor
2009
Operation and
Monitoring Plan
(Post CD & RAP)
2012
2015
Today
2017
Colorado Division
of Reclamation,
Mining & Safety
Telluride Tailings 1-4 Remediation Before & After
Colorado Division
of Reclamation,
Mining & Safety