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Characterization, Cleanup, and Revitalization of Mining Sites

Types of Mining Sites

About 14,000 active and 500,000 abandoned mining sites are estimated to exist across the United States. Three common types of mining sites found in the United States include hardrock, coal, and uranium mines. 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. The unique characteristics of each type of mine (for example, whether the mine is underground or on the surface, the type of material being mined, and other site features) influence the type of contamination that occurs and the remediation and revitalization efforts at a site. The information below provides a brief overview of the types of mines that exist and the leading agencies involved in addressing these sites.

  • USGS Data Release 4.0: Rare Earth Element Occurrences in the United States
    Data release provides describes more than 200 mineral districts, mines, and mineral occurrences (deposits, prospects, and showings) within the United States that are reported to contain substantial enrichments of the rare earth elements (REEs). These mineral occurrences include mined deposits, exploration prospects, and other occurrences with notable concentrations of the REEs.

Hard Rock Mines

Mining for ores and metals such as gold, silver, copper, lead, zinc, and nickel has resulted in tens of thousands of contaminated active, closed, and abandoned hardrock mines in the United States. Hardrock mining sites exist predominantly in the west; most abandoned hard rock mines are found on federal lands in the western United States. However, 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. The EPA AML Program addresses contamination issues at abandoned hard rock mining sites. Over 100 hardrock mines are listed on the Superfund Program's National Priorities List (NPL).

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.
Read more on the Case Studies page

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.
Read more on the Case Studies page

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 calcite, magnetite, iron concentrate, wastewater treatment sludge, and demolition debris. In addition, mining and mining-related activities resulted in contamination by metals and polychlorinated biphenyls, deforestation, and severe erosion.
Read more on the Case Studies page


Coal Mines

Large-scale coal mining arose in the United States during the Industrial Revolution. The majority of coal in the United States is produced in the Appalachian and Midwest regions. In 2010, 1,285 active coal mines producing over one million short tons of coal existed in the United States (U.S. Energy Information Administration). Most coal mining states have primary responsibility for regulating surface coal mining on lands within their jurisdiction. The Office of Surface Mining Reclamation and Enforcement (OSM) performs an oversight role. OSM also partners with states and tribes to regulate mining on federal lands and support state regulatory programs with grants and technical assistance.

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, but a few large sites are in the west. State mining agencies frequently maintain estimates of the number and size of abandoned coal mine lands within their territories. OSM is the principal federal agency responsible for the reclamation of abandoned and contaminated coal mines.

Case Studies

Yankee-Vukonich Coal Reclamation Project, Colfax County, NM
Mining from the 1800s until the 1970s produced substantial amounts of coal waste at the Yankee-Vukonich Coal Reclamation Project site. Most 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.
Read more on the Case Studies page

Fishing Run Restoration and Maude Mine Reclamation Project, South Fayette Township, PA
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.
Read more on the Case Studies page

The Swastika Mine and Dutchman Canyon Reclamation Project
The Swastika Mine and Dutchman Canyon Reclamation Project received a 2012 Excellence in Reclamation Award from the New Mexico Energy, Minerals, and Natural Resources Department's Mining and Minerals Division. This is the first large geomorphic reclamation project within the New Mexico Abandoned Mine Land Program.
Read more on the Case Studies page

Dents Run AML/AMD Ecosystem Restoration Project
The Dents Run AML/AMD Ecosystem Restoration Project is a $14.2 million mine restoration project conducted in the Dents Run watershed in Elk County, Pennsylvania by the Pennsylvania Department of Environmental Protection (PA DEP) and partners. The reclamation project restored and re-vegetated 320 acres of abandoned mine lands that will now serve as habitat for wildlife, including the state's wild elk herd, which roam the adjacent Elk State Forest and game lands. Almost five miles of the lower Dents Run stream also were restored by neutralizing acid mine water. The stream can now support aquatic life for the first time in more than a century.
Read more on the Case Studies page


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.

The regulation and cleanup 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 land management agencies within the U.S. Department of the Interior. 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 of uranium mining sites often is 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.
Read more on the Case Studies page

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.
Read more on the Case Studies page

Cleanup References


Other Mine Types

Numerous other types of mining sites exist across private, state, federal and other lands. These include iron, phosphate, sand, and gravel mines, as well as clay pits and quarries. Many of these mining sites are handled by state and local authorities. State agencies with mining programs are listed in the U.S. Department of Labor's Mine Safety and Health Administration resource area. More information on abandoned mining sites can be found through the Abandoned Mine Lands Portal.