An abandoned mine refers to a former mining or quarrying operation that is no longer in use and has no responsible entity to finance the cost of remediation and/or restoration of the mine feature or site. Such mines are typically left unattended and may pose safety hazards or cause environmental damage without proper maintenance. The term incorporates all types of old mines, including underground shaft mines and drift mines, and surface mines, including quarries and placer mining. Typically, the cost of addressing the mine's hazards is borne by the public/taxpayers/the government.^[1][2][3][4]

An abandoned mine may be a hazard to health, safety or environment.

Hazards

Abandoned mines contain many hazards, including:

• Subsidence, or collapsing ground.
• Blasting caps, dynamite and other (often highly unstable) undetonated explosives that may be accidentally triggered.
• Blackdamp, which accumulates in old mines and can cause suffocation.
• "Bad Air", or poisonous gases and lack of oxygen from unventilated tunnels.
• Hidden mine shafts, often hidden beneath bushes, grasses, and other vegetation that has grown up around the mine entrance, or boarded over with timbers that deteriorate to the point they can no longer support weight.
• Unstable tunnels, roofs and passageways, which are prone to cave-ins.
• Rotting, unsafe timbers and ladders, which are prone to collapse.
• The presence of venomous snakes, arachnids and other dangerous animals.
• Deep, cold pools of contaminated water and flooded tunnels that carry a high risk of drowning, hypothermia or water-borne diseases.
• Poisoning from hazardous remnants of mined elements, including lead or radon.
• Very dark (often pitch-black) and usually complicated layouts that are easy to get lost and/or trapped inside
• Radioactive materials: Some mines, especially uranium mines, can leave behind radioactive materials that pose a serious health risk.
• Falling rocks: Loose rocks can fall from the ceilings of old mines, causing injury.

Abandoned mines in the United States

Definitions

• Department of the Interior – Bureau of Land Management – Abandoned mines are those mines that were abandoned before January 1, 1981, the effective date of the Bureau of Land Management's Surface Management regulations issued under the authority of the Federal Land Policy and Management Act of 1976, as amended (43 U.S.C. 1701 et seq.)^[5]
• Environmental Protection Agency – Abandoned mine lands (AMLs) are those lands, waters, and surrounding watersheds where extraction, beneficiation or, processing of ores and minerals has occurred.^[6]

In the United States, there are thousands of abandoned mines. The precise number of abandoned mines in the United States remains unknown, ranging "from the National Park Service's tally of 2,500 on its lands to the Mineral Policy Center's assessment of 560,000 abandoned mines on public and privately owned lands."^[7] Many of these abandoned mines are associated with abandoned neighboring towns often referred to as ghost towns. Experts strongly warn against entering or exploring old or abandoned mines. In California, Nevada, Colorado, New Mexico, and Arkansas, there are over 6,500 abandoned mines, according to infographic.^[8]

In the U.S., the estimation is that approximately 80% of the abandoned mine lands (AML) sites pose physical safety hazards^[9] and require more work in determining the proper safety of these lands.^[10]

Every year, dozens are injured or killed in recreational accidents on mine property. While exploring abandoned mines can be dangerous, the majority of deaths on mine property are actually unrelated to mine exploration. The leading causes of accidental deaths on abandoned mine properties are drownings in open quarries and ATV accidents. These types of accidents often occur when people engage in recreational activities on abandoned mine sites without taking proper precautions or following safety guidelines. It is important for individuals to recognize the risks associated with these activities and to take steps to ensure their safety. Property owners and managers also have a role to play in preventing accidents by implementing safety measures and providing adequate warning signs and barriers. The U.S. Department of Labor notes that since 1999, "more than 200 people have died in recreational accidents at the surface and underground active and abandoned operations across the country."^[11] Due to these circumstances, the Mine Safety and Health Administration launched the "Stay Out – Stay Alive" campaign, which is a national public awareness campaign aimed at warning and educating children and adults about the dangers of exploring and playing on active and abandoned mine sites.

In the U.S., the Abandoned Mine Land Initiative, launched by the Western Governor's Association and the National Mining Association is also an effort focusing on reporting the number of high-priority AML sites.^[12] The initiative identifies, measures, and reports on the progress of current reclamation cleanup programs on an annual basis. In the Americas region, the United Nations Environment Programme (UNEP) and the Chilean Copper Commission (COHILCO) co-hosted a workshop to address the problem of abandoned or "orphaned" mines.^[13] Including a representative from the UN, ten countries were represented from North, Central, and South America with an eleventh participant being Japan.

Legislation

Surface Mining Control and Reclamation Act

It can be hazardous and detrimental to reside close to an abandoned coal mining site. The Surface Mining Control and Reclamation Act (SMCRA) was passed in 1977 in two parts: one to control the effects of active mines, and one to regulate abandoned mines.^[14] SMCRA also initiated an abandoned mine land fund, in which a fee was charged for each ton of coal produced. This revenue was distributed in part to the United Mine Workers Association (UMWA) towards retirement funds, as well as to the Office of Surface Mining Reclamation and Enforcement (OSMRE) to continue operations. There is still around $2 billion in undistributed funds thus far.

Abandoned mines in Canada

Definitions

• National Orphaned/Abandoned Mines Initiative – Orphaned or abandoned mines are those mines for which the owner cannot be found or, the owner is financially unable or unwilling to carry out clean-up. They pose environmental, health, safety, and economic problems to communities, the mining industry, and governments in many countries, including Canada.^[15]
• The Ontario Mining Act describes "abandoned mines" as old land previously used for coal mining unused due to hazardous environmental and health effects.

There are approximately 10,139 abandoned mines currently in Canada.^[16] Research is being done to utilize geothermal systems in these abandoned mines as a renewable heating source and has shown to be quite cost-efficient.^[17]

Reuse of abandoned mines

Abandoned mines may be reused for other purposes, such as pumped-storage hydropower.^[18]