For more information on Mining Sites, please contact:
Michele MahoneyTechnology Assessment Branch
PH: (703) 603-9057 | Email: mahoney.michele@epa.gov
Characterization, Cleanup, and Revitalization of Abandoned Mining Sites
Types of Abandoned Mining Sites
- Overview
- Types of Abandoned Mining Sites
- Characterization
- Cleanup Technologies
- Revitalization and Reuse
- Events
- Resources and Links
- Presentations
The three most common types of mines found in the United States are hard rock, coal, and uranium mines. The unique characteristics of each type of mine complicate cleanup efforts, which vary in terms of cost and approach. The EPA AML Program addresses contamination issues at abandoned hard rock mine sites, while the Office of Surface Mining Reclamation and Enforcement (OSM) is the principal federal agency responsible for the reclamation of abandoned and contaminated coal mines. The cleanup and regulation of uranium mines is a complex process that is handled jointly by EPA, the U.S. Nuclear Regulatory Commission, the U.S. Department of Energy, and various U.S. Department of Interior land management agencies.
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Hard Rock Mines |
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Uranium Mines |
Other Mine Types
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Hard Rock Mines
Mining for ores and metals such as gold, silver, copper, lead, zinc, and nickel has resulted in tens of thousands of abandoned hard rock mines in the United States. Most abandoned hard rock mines are found on federal lands in the western United States, but no comprehensive inventory is available. Major land management agencies, including the Bureau of Land Management, the U.S. Forest Service, the U.S. Fish and Wildlife Service, and the National Park Service, maintain their own inventories of abandoned mines within the boundaries of the lands they manage.
There are over 100 hard rock mines listed on the Superfund Program's National Priorities List (NPL). Mining operations can create a host of contamination issues, including the release of arsenic, cadmium, zinc, and other metals of concern into the soil and groundwater. The disposal or containment of mining debris and tailings is another serious environmental concern that must be addressed when cleaning up a mining site.
Cleanup remedies and revitalization and redevelopment options at abandoned hard rock mine sites vary according to the mine type, location, and type of contaminant. It can take several years to remediate the contamination at a site. Redevelopment options at former mine sites range from creating community green space to commercial uses such as the siting of renewable energy production facilities.
Case Studies
Silver Mountain Mine, Horse Springs Coule, WA
The Silver Mountain Mine site is an abandoned silver and gold mine that operated from 1928 to the 1960s. In the early 1980s, cyanide was used to extract metals from mine tailings. By 1983, the site was abandoned, and the mine tailings and holding basin, which contained cyanide-contaminated water, were left behind. A leachate collection trench associated with the ore extraction was contaminated with cyanide and arsenic.
California Gulch, Leadville, CO
The California Gulch Superfund site consists of about 18 square miles of land where mining, mineral processing and smelting activities produced gold, silver, lead and zinc for more than 130 years. Wastes generated during the mining and ore-processing activities contained metals such as arsenic and lead at levels that posed a threat to human health and the environment. These wastes remained on the land surface and migrated through the environment by washing into streams and leaching contaminants into surface water and groundwater. The site was added to the NPL in 1983. To facilitate cleanup, it was divided into 12 operable units, each with a specific cleanup activity. EPA and the potentially responsible parties conducted removal and remedial activities to consolidate, contain, and control more than 350,000 cubic yards of contaminated soils, sediments and mine-processing wastes. Cleanups by the potentially responsible parties have involved drainage controls to prevent acid mine runoff, consolidation and capping of mine piles, and slag reuse. As of 2011, several of the operable units at the site have been deleted from the NPL. Response actions are complete in most of the operable units, and institutional controls to protect the remedy and prevent the release of contaminants are either in place or under development.
Copper Basin Mining District, TN 
The Copper Basin Mining District has been heavily scarred by mining activities that continued from the mid-1800s until the late 1900s. Mining and processing activities centered on copper and sulfur, and produced solid wastes and byproduct materials that remain on site, including sulfide-rich ore, sulfide-bearing waste rock, tailings, granular and pot slag, iron calcine, magnetite, iron concentrate, wastewater treatment sludge, and demolition debris. In addition, mining and related activities resulted in contamination by metals and polychlorinated biphenyls, deforestation, and severe erosion.
Surface Impoundment for the Davis Mill Creek Watershed Wastewater Treatment Plant
Several government agencies and private parties have taken steps to stabilize and partially revegetate the area, including its numerous watersheds. The site is being investigated and cleaned up through a collaborative effort between the EPA, the Tennessee Department of Environment and Conservation, and OXY Oil and Gas USA. A wastewater treatment plant was refurbished on the Davis Mill Creek watershed to treat acid and metal-laden waters of the creek, underground mine waters, and contaminated stormwater. The plant has removed over 5 million pounds of iron, zinc, manganese, copper, lead and cadmium, and neutralized over 13 million pounds of acid. The Davis Mill Creek watershed also received diversion systems and upgrades and modifications to existing dams. The North Potato Creek received a lime treatment plant that removed 90 percent of metals of ecological concern and raised the pH of the discharge from 3.3 to 7.0. One of the goals for this watershed is to re-establish its biological integrity. This process is currently in progress.
Coal Mines
Large-scale coal mining arose in the United States during the Industrial Revolution. Most of the thousands of abandoned coal mines are found on state-owned land in the eastern United States. Sixty percent of these abandoned coal mines are located within Kentucky, Pennsylvania, and West Virginia, though a few large sites can also be found in the west. State mining agencies frequently maintain estimates of the number and size of abandoned coal mine lands within their territories.
Case Studies
Yankee-Vukonich Coal Reclamation Project, Colfax County, NM
Yankee-Vukonich Coal Reclamation Project, Colfax County, New Mexico
Mining from the 1800s until the 1970s produced substantial amounts of coal waste at the Yankee-Vukonich Coal Reclamation Project site. The majority of the waste was found dumped down steep slopes and near streams, where it was contaminating both ephemeral and perennial waterways. Partially collapsed mine entrances also were a major issue.
The reclamation project for the 2.9-acre site was completed in 2005. The goal of the project was to establish vegetation on coal mass piles to reduce erosion and siltation of downstream waterways, and to restore the meanders of the stream that had been straightened by sediment deposition during the active mining period. Revitalization activities included mixing coal waste with native soil while adding lime, gypsum, wood waste, and compost to support native vegetation; reseeding at designated areas and areas disturbed by construction; restoring stream meanders through excavation, filling, and engineered structures; and others. The project has successfully restored vegetation at the site so that it blends in with undisturbed areas. In addition, streams have been reshaped to a natural state and historic buildings from the mining era have been preserved.
Fishing Run Restoration and Maude Mine Reclamation Project, South Fayette Township, PA
Maude Mine Reclamation Project, Allegheny County, Pennsylvania
The Fishing Run Restoration and Maude Mine Reclamation Project site was mined from the 1800s through the early 1900s. Large-scale underground mining operations began toward the end of the 19th century to keep up with energy demand generated by the growing steel industry in Pittsburgh. The site included an open portal, a partially sealed mine opening, 1,500 feet of hazardous highwall, and numerous dilapidated coal-facility structures. The open mine portal captured and diverted all of the flow from the upper portion of the Fishing Run stream. The water captured by the portal flowed through an abandoned mine and then discharged as acid mine drainage into a major stream.
Specific reclamation and revitalization activities included the demolition, removal, and disposal of the abandoned coal preparation structures; elimination of the highwall areas through excavations and fills; and sealing of the open mine portal and a partially sealed mine opening. In addition, the Pennsylvania Department of Environmental Protection's Bureau of Abandoned Mine Reclamation restored Fishing Run to a natural streambed, which is now lined with over 4,000 trees for stream-bank restoration and establishment of a riparian buffer zone.
Uranium Mines
The uranium mining industry arose in the United States during the 1940s. Its primary purpose was to provide uranium for weapons, and later, for nuclear fuel. There are about 15,000 locations associated with uranium, of which 4,000 are mines with documented production. Most mines that produce uranium as a primary commodity are located, in Colorado, Utah, Wyoming, New Mexico and Arizona. Uranium mines typically are located on federal and tribal lands.
Federal agencies that address uranium sites are the U.S. Nuclear Regulatory Commission, the U.S. Department of Energy, EPA, and various federal land management agencies. EPA works to address hazards posed by technologically enhanced naturally occurring radioactive materials. Some uranium mines are addressed through the Superfund program. Two were listed on the NPL as of 2007, while others are listed in the EPA Comprehensive Environmental Response, Compensation and Liability Information System (CERCLIS) hazardous waste database. The CERCLIS database, however, does not reflect the current reclamation status of the approximately 15,000 uranium locations.
Cleanup and revitalization options at uranium mines vary. During cleanup, it is important to address overburden and waste rock, mill tailings, as well as water-one of the principal pathways for dispersal of uranium mining pollutants into the environment-that comes into contact with uranium. The techniques used to clean up former uranium mining sites vary on a site-by-site basis and depend upon the regulatory agencies involved.
Revitalization and redevelopment are often complicated. Radiation from closed sites remains a potential risk for thousands of years due to the long half-lives of uranium isotopes and their daughter products. Therefore, long-term monitoring of air and water pathways often is necessary to ensure that cleanup was successful. Monitoring is especially important because, while most conventional uranium sites are located in rural and remote areas away from population centers, many others are close to or within populated communities, including parts of the Navajo Nation. Some also may be accessible to recreational visitors on federal lands.
Case Studies
Abandoned Uranium Mines, Navajo Nation
The Navajo Nation is situated on a geologic formation rich in radioactive ores including uranium. Beginning in the 1940s, widespread mining and milling of uranium ore for national defense and energy purposes on the Navajo Nation led to a legacy of abandoned uranium mines. Some Navajo residents may have elevated health risks due to the dispersion of radiation and heavy metal contamination in soil and water.
EPA maintains a strong partnership with the Navajo Nation. Since 1994, the Superfund program has provided technical assistance and funding to assess potentially contaminated abandoned uranium mine sites and develop a response. In August 2007, the Superfund program compiled a Comprehensive Database and Atlas with the most complete assessment to date of all known uranium mines on the Navajo Nation. Working with the Navajo Nation, EPA also used its Superfund authority to clean up four residential yards and one home next to the highest priority abandoned uranium mine, Northeast Church Rock Mine, at a cost of more than $2 million.
In 2008, EPA, in partnership with the Department of Energy, the Bureau of Indian Affairs, the Indian Health Service and the Nuclear Regulatory Commission, finalized a five-year plan for cleaning up the abandoned uranium mining on the Navajo Nation. Under the Five-Year Plan, U.S. EPA works with the Navajo Nation EPA to conduct a tiered assessment of abandoned mines, identify mines for more detailed assessments, and determine appropriate courses of action for the highest-priority mines. By the spring of 2010, EPA completed 192 on-site screen evaluations of abandoned uranium mine sites in the Eastern and Northern abandoned uranium mine regions and completed more detailed assessments at four additional mines. In 2011, EPA expected to conduct screening-level review and site visits of an additional 134 abandoned uranium mine sites in the Northern and Western abandoned uranium mine regions. EPA also completed removal assessments for the Skyline Mine and the Northeast Church Rock "Quivira" Mine.
Uravan Mill Site, Uravan, CO
In September 2008, EPA Region 8 certified the completion of the 20-year, $120-million cleanup of the Uravan Mill Superfund site in Colorado. The former uranium and vanadium mine and processing site is located along the San Miguel River in western Montrose County. The 680-acre site is contaminated with radioactive residues, metals and other inorganic materials.
During the cleanup, more than 13 million cubic yards of mill tailings, evaporation pond precipitates, water treatment sludge, contaminated soil, and debris from more than 50 major mill structures were collected and disposed in four on-site repositories. More than 380 million gallons of contaminated liquid collected from seepage containment and groundwater extraction systems were treated at the mill site. The site and surrounding area will be used in the future for recreation and as a wildlife habitat. One portion of the site will be transferred to DOE for long-term management, while another will be used as a campground and visitor center, complete with a museum dedicated to uranium mining and milling in Western Colorado.
Other Mine Types
A variety of other types of abandoned mines exist across private, state, federal and other lands. These include iron, phosphate, sand, gravel, clay pits, quarries, and others. These types of abandoned mine lands are handled by state and local authorities, rather than through federal programs. For more information, please visit the Abandoned Mine
Lands Portal.
