National Priorities List (NPL) History
Site Type: Final NPL
Updated October 2011
The U.S. Environmental Protection Agency, the Colorado Department of Public Health and Environment (CDPHE) and the U.S. Forest Service (USFS) signed the Record of Decision (ROD) on September 30, 2011 for the Standard Mine Superfund Site. The ROD documents EPA's long-term cleanup strategy. Following the initial phase, EPA will monitor the site to determine if a second phase will be needed. Phase 1 includes actions to limit groundwater movement from the upper mine workings to the lower workings to minimize groundwater contamination; construction of a bulkhead to regulate flow from Level 1; revegetation of existing waste rock piles; land use controls to minimize human exposure to site contaminants; and monitoring. Phase 2, if needed, includes passive biological treatment of the contaminated mine discharge and continued monitoring.
The Standard Mine site is located on 10 acres in the Ruby Mining District of the Gunnison National Forest, approximately 30 miles north of Gunnison and 10 miles west of the Town of Crested Butte, in Gunnison County, Colorado. The contaminants of concern are primarily heavy metals with samples showing elevated levels of manganese, lead, zinc, cadmium, and copper. The site releases a high flow of 70 gallons per minute (gpm) and a low flow of 5-20 gpm, depending on the season, of contaminated discharge from the abandoned mine workings into Elk Creek.
Silver mining activity began in the southern Ruby Mining District in 1874, and continued up to 1974 at several mine sites. Standard Mine was one of the three largest producing silver mines in the area. The other two are the Keystone Mine (owned by Phelps Dodge) and the Forest Queen Mine. None of these mines is currently active except for water treatment at the Keystone Mine. The Standard Mine was called the most environmentally-degraded mine site in the entire Ruby Mining District by a report from the Colorado Geological Survey.
|Media Affected||Contaminants||Source of Contamination|
|surface water, groundwater, soil||arsenic, lead, zinc, cadmium, copper, chromium and manganese||mining|
Mining operations have greatly disturbed the land, creating highly mineralized conditions at the site. Mineralized waste rock exposed to air and water causes acidic conditions to mobilize the release of heavy metals to the surrounding environment. These heavy metals are deposited into Elk Creek, which flows into Coal Creek and eventually to downstream water users.
A Remedial Investigation and Feasibility Study (RI/FS) began after the site was listed on the National Priorities List (NPL) as a Superfund site in 2005. An RI is the first step taken to characterize the site. This consists of collecting information on the physical aspects of the site such as types and location of contamination. The information is analyzed and presented in an RI report that is used for addressing potential cleanup actions.
The next step is to prepare an FS, which is an evaluation of various alternatives for cleanup of the site in order to determine the most feasible, cost effective, implementable, and protective final cleanup strategy for the site. The FS uses information collected during the RI, as well as a risk assessment, to determine the cleanup goals for the site.
Under EPA's Emergency Response Program, a non-time-critical process was initiated to address more immediate contamination concerns at the site. EPA, under a contract with URS Operating Services, developed and made available to the public an Engineering Evaluation/Cost Analysis (EE/CA) for the site. The first phase of the EE/CA discussed options for identifying an appropriate location for a repository to contain contaminants removed from the Standard Mine site. The second phase of the EE/CA focused on selection of the repository site, capping alternatives, and removal alternatives for addressing mine waste at the site, including the tailings impoundment located adjacent to Elk Creek.
Elk Creek flows through the site depositing heavy metals into Coal Creek, which runs through the town of Crested Butte until it meets the Slate River. The Crested Butte municipal drinking water intake is on Coal Creek. As a result, there is a potential threat to downstream water users from the Standard Mine.
The site is located at an elevation of 11,000 feet in a very remote and isolated location on the south flank of the Scarp Ridge in Elk Basin. It is only accessible in the summer by four-wheel-drive vehicles, by foot, or by mountain bike. The site historically consisted of waste piles along with open and unmarked adits (horizontal) and shafts (vertical) with the following characteristics:
- 8400 feet of drifts on six levels (opens in pop-up)
- 53,560 cubic yards of waste rock
- 29,340 cubic yards of mill tailings
- Non-engineered and unlined surface impoundment 300 feet in diameter and 15 feet deep constructed entirely of waste rock
- Dilapidated buildings and rail structures (opens in pop-up)
2006 to Present—Cleanup Activities
During the 2006 construction season some of the activities that EPA accomplished were:
- Improved the access road to the site to assist with cleanup activities
- Channelized the surface water to reduce the potential for contamination of the surface water and reduce the amount of water that flows into the tailings impoundment
- Centralized the mining debris to facilitate removal of contaminated materials
- Re-channeled Elk Creek to protect it from contaminated soils at the site, and to keep Elk Creek water from eroding and transporting contaminated soils and materials during the cleanup
In December, 2006 EPA made available for public comment the first phase of the EE/CA, which discussed proposed options for the location of a repository site. A repository site is a central place where contaminated mine waste removed from the Standard Mine can be permanently stored and maintained to ensure that recontamination does not occur. The second phase of the EE/CA covering the repository design was available for public comment in May 2007. EPA's response to comments received and attachments can be found in the Site Documents section below.
During the 2007 construction season, EPA built a mine waste repository to permanently contain waste rock and tailings, which were removed to the repository later that season. By the end of the construction season, EPA had removed approximately 50,000 cubic yards of waste material, which included full removal of the tailings impoundment. EPA also installed a passive-treatment pilot-scale bioreactor to determine if this type of passive water treatment is effective at the mine's high elevation and cold winter climate. In addition, EPA initiated a revegetation pilot study to help determine successful methods for establishing vegetation within the excavated areas and to support reclamation efforts to be implemented at a later time.
During the 2008 construction season, EPA accomplished the following cleanup activities:
- Installed sediment controls along Elk Creek to reduce the risk of sediment flowing into the creek
- Excavated and hauled contaminated mine waste to the repository
- Screened soil taken from a borrow area to be used for capping the repository and future revegetation activities
- Restored and realigned Elk Creek
- Completed the repository, including the installation of drainage ditches around the perimeter
- Applied compost, lime, fertilizer, top soil, and native seed to areas affected by the initial cleanup activities as part of the revegetation of these areas
- Continued monitoring of the passive-treatment pilot-scale bioreactor resumed for the summer
Community involvement plays an important role in the Superfund process. EPA uses a number of different tools and resources to promote effective, on-going, meaningful community involvement. The goals of the Superfund community involvement program are to:
- Keep communities affected by sites informed throughout the cleanup process
- Provide opportunities for communities to comment and offer their input about site cleanup plans
- Facilitate the resolution of community concerns related to the site cleanup
According to the National Contingency Plan (NCP) 40 CFR 300.430(c)(2)(ii), a Community Involvement Plan (CIP) is required as part of any remedial action at a Superfund site. A CIP specifies the outreach activities that EPA will undertake to address community concerns and expectations. EPA has finalized the Standard Mine Community Involvement Plan. The final plan is available on this website and included in the information repository located at the Crested Butte Library. The CIP is located in the Site Documents section below.
Community Advisory Group
A Community Advisory Group (CAG) has been organized for the site cleanup. Participants include EPA, CDPHE, the U.S. Forest Service, local government, and citizens, however the meetings remain open to any citizen who would like volunteer or simply come to observe. Information concerning the topics of discussion and the agenda can be found in the Notes. The meetings will be advertised in the Crested Butte News one week in advance. The name of the CAG for Standard Mine is the Standard Mine Advisory Group (SMAG).
Technical Assistant Grant
EPA provides Technical Assistance Grants (TAGs) to communities to help citizens understand site-related information. A TAG can be used to hire a technical advisor to explain to the community technical information related to the cleanup and help articulate the community's concerns. In 2006, community members in Crested Butte applied for and were awarded a TAG through the EPA. The group that received the grant is called the Standard Mine Technical Advisory Group (SMTAG).
If you have any questions about the SMAG or the SMTAG, or would like to be added to either e-mail list, please contact Pat Courtney.
EPA places a high priority on land reuse as part of its Superfund response program mission. The Agency tries to select cleanup options that encourage and support future use of a site. We use two fundamental methods to facilitate reuse of Superfund sites:
- Exploring future uses before the cleanup remedy is implemented, an approach that gives the Agency the best chance of designing cleanup remedies to support the likely future use of a site
- Working with landowners and communities to remove barriers not considered necessary for the protection of human health or the environment at those sites where remedies are already in place
One option for reuse is the siting of clean and renewable energy projects on contaminated (or formerly contaminated) lands. As part of this effort, EPA is evaluating the potential for energy projects on these properties and working with landowners and communities to identify ways to remove barriers to such projects.
The reasonably anticipated future land use is determined during the Remedial Investigation/Feasibility Study process. This information is considered during the development and selection of the remedy for the site.
Land Use Controls and Other Institutional Controls
Land use controls are the most common type of institutional control (IC). ICs are administrative or legal controls that help reduce the likelihood for human exposure to contamination. ICs can also help protect the integrity of the remedy. Examples of ICs are:
- Zoning ordinances
- Environmental covenants
- Deed notices
- Well-drilling restrictions
- Building permits
- Informational advisories
Institutional controls were selected as one of EPA’s preferred alternative in the proposed plan because environmental covenants are required when source materials are left in place. Environmental covenants are used to limit the use of property where waste is left in place. Often these include limiting the use of contaminated groundwater, restricting excavation, and limiting the ways in which contaminated property may be used in the future (i.e., residential or commercial use). Site access controls such as fencing and signs could also be used to limit human contact with site contaminants or treatment systems.
EPA or the lead agency conducts five-year reviews following the start of a Superfund cleanup when contamination is left on the site. These reviews are repeated every five years. We use these reviews to determine:
- How the remedy is working
- If the remedy remains protective of human health and the environment
Five-year reviews are not yet required at this site.
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Nature and Extent of Contamination at Standard Mine
Groundwater Well Drilling Report, December 23, 2008 (PDF, 43 pp, 11.9MB)
EPA response to SMTAG comments on the RI report, April 30, 2010 (PDF, 4 pp, 92K)
EPA responses to comments on the draft RI report, March 11, 2010 (PDF, 5 pp, 97K)
Remedial Investigation (RI) Report, May 27, 2010 (PDF, 235 pp, 258MB)
Appendices (located on our FTP server – opens in new tab/window)
Evaluation of Long-Term Cleanup Options
Proposed Plan for Public Comment, June 7, 2010 (PDF, 12 pp, 791K)
Action Memo, June 9, 2006 (PDF, 28 pp, 803K)
Phase I Engineering Evaluation/Cost Analysis (EE/CA), April 1, 2007 (PDF, 350 pp, 25.4MB)
EPA responses to comments on the Phase I EE/CA, April 17, 2007 (PDF, 22pp, 992K)
Phase II EE/CA, July 2, 2007 (PDF, 128 pp, 7.5MB)
EPA responses to comments on the Phase II EE/CA, July 28, 2007 (PDF, 27 pp, 1.7MB)
Action Memo, July 10, 2007 (PDF, 31 pp, 6.9MB)
Standard Mine Reclamation Plan, May 23, 2008 (PDF, 24 pp, 212K)
EPA response to comments on the draft FS report, May 2010 (PDF, 14 pp, 187K)
Feasibility Study (FS) Report, May 27, 2010 (PDF, 205 pp, 28.8MB)
Appendix A (PDF, 106 pp, 6.5MB)
Appendix B (PDF, 123 pp, 76MB)
Assessment of Risks Posed by Standard Mine Site Contaminants
U.S. Fish and Wildlife Service Interpretation of Standard Mine Site Data, April 2007 (PDF, 7 pp, 335K)
Human Health Risk Assessment (HHRA), March 19, 2008 (PDF, 39 pp, 228K)
HHRA Appendices (PDF, 83 pp, 498K)
HHRA Figures (PDF, 7 pp, 1.6MB)
HHRA Tables (PDF, 22 pp, 158K)
Baseline Ecological Risk Assessment (BERA), May 14, 2007 (PDF, 52 pp, 210K)
BERA Appendices A–H and J–M (PDF, 154 pp, 870K)
BERA Appendix I (PDF, 125 pp, 11.5MB)
BERA Figures (PDF, 22 pp, 906K)
BERA Tables (PDF, 18 pp, 121K)
EPA response to community comments on HHRA Addendum (PDF, 3 pp, 46K)
HHRA Addendum, November 2009 (PDF, 55 pp, 1.8MB)
Elk Creek Fish Habitat Evaluation, December 2009 (PDF, 14 pp, 654K)
BERA Addendum, May 25, 2010 (PDF, 51 pp, 242K)
BERA Addendum Appendices (PDF, 140 pp, 4.3MB)
BERA Addendum Figures (PDF, 25 pp, 2.6MB)
BERA Addendum Tables (PDF, 11 pp, 91K)
Geochemical Investigations and Mapping of Underground Mine Workings
Colorado DRMS Underground Investigation of Standard Mine Level 2, Gunnison County, Colorado, October 2009 (PDF, 26 pp, 829K)
USGS Hydrogeochemical Investigation of the Standard Mine Vicinity, Upper Elk Creek Basin, Colorado, 2007 (PDF, 142 pp, 6.3MB)
USGS Hydrogeochemical Investigation of the Standard Mine Vicinity, Upper Elk Creek Basin, Colorado – Standard Mine Advisory Group presentation, December 2007 (PDF, 18 pp, 2.1 MB)
USGS Geochemistry Report on Standard Mine Waters, July 2009 (PDF, 28 pp, 4.9MB)
Colorado DRMS Underground Assessment of the Standard Mine Superfund Site, Gunnison County, Colorado, December 2007 (PDF, 43 pp, 2.9MB)
Sampling Activities Reports
2006 Sampling Activities Report (PDF, 350 pp, 42MB)
2007 Sampling Activities Report (PDF, 179 pp, 25MB)
2008 Sampling Activities Report (PDF, 127 pp, 1MB)
2010 Sampling and Analysis Plan/Quality Assurance Project Plan (PDF, 26 pp, 2.3MB)
Water Treatment Pilot Study
Standard Mine Pilot Passive Treatment System Operations and Results for 2007 and 2008, August 2009 (PDF, 306 pp, 8.7MB)
Community Involvement Documents
Final Community Involvement Plan, June 2006 (PDF, 25 pp, 358K)
Site-Wide Cleanup Implementation and Decision Documents
Record of Decision, September 30, 2011 (PDF, 123 pp, 4.2MB)
EPA Superfund Project Manager
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (8EPR-SR)
Denver, CO 80202-1129
800-227-8917 ext. 312-6009 (toll free Region 8 only)
Community Involvement Coordinator
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street (8OC)
Denver, CO 80202-1129
800-227-8917 ext. 312-6631 (toll free Region 8 only)
State Superfund Project Manager
Colorado Department of Public Health and the Environment
4300 Cherry Creek Drive South
Denver CO 80246-1530
888-569-1831 ext. 3390 (toll-free)
Crested Butte Old Rock Library
782 Elk Avenue
Crested Butte, CO 81224
EPA Superfund Records Center
1595 Wynkoop Street
Denver, CO 80202
800-227-8917 ext. 312-6473 (toll free Region 8 only)
Click on a thumbnail below to view the full size image.
Level 1 structures from tailings dam before cleanup
Level 1 structures from tailings dam after cleanup
Standard Mine before cleanup
Level 1 adit before cleanup
Level 3 underground workings showing fault
Level 2 adit before cleanup
Level 3 muck pile in underground workings
Mill site loading structures before cleanup
Mill site loading structures after cleanup
Tailings dam and Elk Creek after cleanup