Mining wastes

Mining has produced vast areas of disturbed land and disrupted ecosystems. The magnitude of extraction activities, combined with inadequate responses by mining companies, has prompted reclamation laws and research.

By-products of Mining

For centuries, humans have continually found uses for Earth's minerals and have been able make useful deposits of lower and lower economic content. Miners remove 15 meters or more of overburden (soil and rock) to obtain 30 centimeters of coal. Some copper mines process ores present in concentrations as low as 0.5 percent. These endeavors literally produce mountains of waste product, referred to as spoil. All human exploitation of Earth's resources produces byproduct waste, but none produces more than the mining of coal. Another inevitable by-product is ecosystem disruption—the alteration of plant and animal habitat—and changes in hydrology, which includes all aspects of water. Reclamation is the effort to heal the altered environment through landform modification, revegetation, and erosion control.

Until the mid-twentieth century, a “use it” ethic of land use was dominant. Nature was all too often seen as an enemy to be conquered. Since World War II, however, and with the rise of environmental concerns, the United States has recognized the need to restore these disturbed lands. Nevertheless, coal strip mining has increased with the growing demand for energy. Between the 1930s and early 1970s, electrical demand doubled every decade. When the 1973 energy crisis hit, the huge deposits of western coal were seen as one pathway to energy independence. Additionally, the abrupt halt in orders for new nuclear power plants meant that almost all new electrical power plants since 1973 have been fueled by coal.

Growing Concern for the Environment

Reclamation efforts in the past have been unremarkable due to issues of apathy, cost, and the relatively small areas involved. Current efforts are directly linked to the growth of conservation and environmental movements in response to population growth and the development of available lands. In the United States, population and economic growth following World War II resulted in pollution conditions that shocked the nation. The first large-scale environmental conference was held at Princeton University in June 1955. Entitled “The International Symposium on Man’s Role in Changing the Face of the Earth,” it set the agenda for rising environmental concerns across the nation. Stewart Udall, then secretary of the interior, made an instrumental contribution in the 1967 publication Surface Mining and Our Environment: A Special Report to the Nation, a clear call to confront the growing problem of unreclaimed coal strip mines (described in the text as “orphan” lands).

A seminal example of legislation is the Mining Law of 1872, which created liberal and inexpensive conditions for establishing mining claims on federal lands to promote western metal mining. Opponents of mining regulation have resisted all efforts to amend the law, so mining laws since can be mostly described as nibbling around the edges of the 1872 law. Issues emerge in attempting to regulate resources, such as coal that are not addressed in the law and mining on land, a topic not mentioned in the 1872 law. The World Population Review considers coal to be the dirtiest fossil fuel because it emits significant amounts of greenhouse gases and other pollutants into the air when it is burned. Since coal generates such a large proportion of mining waste, the ability to regulate coal mining has allowed the federal government to control some of mining’s worst problems.

The creation of the Environmental Protection Agency in 1970 led the way to what came to be called “the environmental decade.” The Surface Mining Control and Reclamation Act of 1977, though covering only coal mining, was landmark legislation. It requires revegetating and restoring the land to its approximate original contour; bans the mining of prime agricultural land in the West and in locations where owners of surface rights object; requires operators to minimize the impact on local watersheds and water quality; establishes a fee on each ton of coal to help reclaim orphan lands; and delegates enforcement responsibility to the states, except where they fail to act or where federal land is involved.

However, concerns about mining waste from coal have become significant again in the twenty-first century. The mandatory lockdowns during the COVID-19 pandemic disrupted the coal mining industry, including its management of waste. If a mining company suddenly departs from an area and leaves its waste behind, it can seep into the soil and water. This puts nearby communities at risk.

The use of coal increased by 1.2 percent from 2021 to 2022, the largest increase since 2013. This increase was largely caused by a rise in the price of natural gas. In 2022, the global consumption of coal was more than 8 billion tons. However, experts believe that short- and long-term environmental monitoring can help coal companies monitor and manage their increase in mining waste.

Water Quality and Hydraulic Impacts

Important research on water quality dates from the 1950s and was focused on acid mine-drainage problems in Appalachia, where it has long been recognized as a problem. Acid is produced in any type of earth movement where iron pyrite and other sulfides are removed from a reducing environment to an oxidizing one. Within the earth these sulfides are stable, but when exposed to oxygen and water they readily oxidize, producing sulfuric acid, the main ingredient in acid-mine drainage. Coal strip mines can produce acid when the sulfide-rich layers above and below the coal (often called fire clay) are scattered on the surface or left exposed in the final cut. A major issue of reclamation is the need to identify these acid-producing materials and bury them. Acids speed up the release of dangerous metals such as aluminum and manganese, which can be toxic to vegetation; they also cause deformities in fish.

Hydrologic impacts mainly involve changes in runoff and sediment. A major study was conducted by the US Geological Survey in Beaver Creek basin, Kentucky. This area was selected because mining operations were just beginning there under typical Appalachian conditions. Data collected from 1955 to 1963 revealed large increases in runoff and sediment. By contrast, another study in Indiana demonstrated the tremendous water-holding capacities of the disturbed lands. The surface topography had much to do with the different results because a more level condition existed in Indiana. Another study was conducted at a basin in northeastern Oklahoma while the area was being subjected to both contour and area strip mining. After initial increases in runoff and erosion, huge decreases occurred as much of the drainage became internalized. When reclamation began under a new state law, however, erosion rates comparable to unprotected construction sites were measured (up to 13 percent sediment by weight). Clearly, slopes lacking a protective vegetation cover will produce much more runoff, which in turn will carry enormous sediment loads. Nevertheless, in several orphan lands, water and sediment are trapped internally because of the drainage obstacles and depressions created by the mining operation.

Uses of Mining Waste Landforms

Early research on mining wastes involved description of the new landforms created by human activity. The landforms produced by strip mining that are still visible in orphan lands and have yet to be reclaimed are spoil banks, final-cut canyons (which are often filled with ponds), headwalls (above the final cuts), and transport roads. Mining waste landforms have some interesting uses. Perhaps most important is recreation, especially fishing in final-cut ponds. Many abandoned quarries are used by scuba divers for training. In some North Dakota mines, natural revegetation has formed refuges for deer and other wildlife. One site in northeastern Oklahoma, given to the local Boy Scouts, now supports a dense population of trees and birds and is a wonderful small wilderness. Other uses include forestry in the East and sanitary landfills near urban areas. Most softwoods, such as pine, prefer more acidic soils, which are common in eastern strip mines. Use in sanitary landfills is aided by the already disturbed condition of the land and by the fact that the clays and shales commonly found in coal strip mines provide relatively impermeable conditions. One oft-neglected potential use of mined lands is education, as mine cuts can provide access to rock outcrops and geologic features not otherwise accessible.

The linkage between mining waste landforms, vegetation/soil conditions, and erosion was recognized early. One study in Great Britain found that even in successfully revegetated strip mines, erosion rates were 50 to 200 times those of undisturbed areas. Revegetation is the key to reclamation; it, in turn, is heavily dependent upon the quality of the soil. Because of the diverse nature of soil and local ecosystems, a specific reclamation plan is never made easily.

Effective Reclamation Planning

Effective reclamation plans require sufficient data on soil pH (a measure of acidity or alkalinity), soil chemistry for fertility and toxicity problems, water retention capability, soil organisms, and useful native plants, especially perennials. The best way to provide the necessary soil conditions is to save and rapidly replace the topsoil and establish a vegetation cover quickly in order to protect the soil from rain and gully erosion. Even thin layers of good topsoil are a major improvement over the deeper subsoils, which tend to be low in organic matter and rich in acid-producing sulfides.

Detailed planning is an integral part of the reclamation process. When planning is completed before mining begins, some of the impact can be minimized and reclamation can proceed in concert with mining, shortening the interval before replanting. Since erosion is highly destructive to revegetation efforts, erosion control systems are vital. They are designed to direct the flow of water and to dissipate its energy, enhancing soil moisture for vegetation.

Also vital to a good reclamation plan is a thorough understanding of local ecosystems and the potential success or failure of restoration efforts. Revegetation is mainly an exercise in ecological succession. Once an ecosystem is disrupted, it is difficult to reestablish. In some cases, it may be wiser to pursue a different course. Because ecological succession is slow, fifty years or more may be needed to gauge success or failure accurately.

Need for Conservation and Recycling

The need for conservation and recycling is supported by the ecological axiom that, in nature, matter cycles but energy flows. By recycling matter, large energy savings can result from the reuse of materials such as steel, aluminum, and glass. Because energy flows, and therefore cannot be recycled, conservation is the best source of additional energy. These savings reduce the pressure to disturb more land for energy-producing coal. A key factor in the environmental impact of mining is the adaptability of natural ecosystems. How much stress can they tolerate, and what kind of conditions can be expected from the consequent ecological succession? Ecosystems are remarkably resilient and adaptable. Still, the pace of human activity is so rapid and the recovery of ecosystems so slow that humans would be wise to err on the side of conservation.

In the early twenty-first century, questions began being raised about the impact of coal burning on potential atmospheric heating. Coal is nearly pure carbon. Carbon dioxide is a waste product produced when carbon is burned. It is also a major greenhouse gas that absorbs and traps heat radiating from the earth’s surface. The world’s long running dependence on coal for electrical power production contributes to climatic changes, which impacts agriculture. Revegetation efforts can help in this area because growing plants remove carbon dioxide from the atmosphere. One potential replacement for coal, nuclear power, has its own set of mining waste problems, along with a need for long-term storage of radioactive wastes.

Two opposing land-use viewpoints provide a framework for discussion—the historic “use it” ethic and the growing “preserve it” ethic. Many prefer a middle road of scientific conservation or sustainable Earth practices, both of which include reclamation. A political perspective raises the issues of tolerance levels and affordability. The government has a responsibility to protect the health and welfare of its citizens. Where clear dangers exist, the government has a responsibility to act. Pollution issues tend to be controversial, and the tradeoff between benefits and costs of particular interventions abound. Humanity cannot use Earth’s resources without causing pollution, and there are limits to what can be done to abate it. Still, public support tends to be mixed for pollution control, cleanup of past pollution problems, and reclamation of disturbed land.

Principal Terms

ecological succession: the process of plant and animal changes, from simple pioneers such as grasses to stable, mature species such as shrubs or trees

ecosystem: a self-regulating, natural community of plants and animals interacting with one another and their nonliving environment

erosion: the movement of soil and rock by natural agents such as water, wind, and ice, including chemicals carried away in solution

landforms: surface features formed by natural forces or human activity, normally classified as constructional, erosional, or depositional

orphan lands: unreclaimed strip mines created prior to the passage of state or federal reclamation laws

reclamation: all human efforts to improve conditions produced by mining wastes—mainly slope reshaping, revegetation, and erosion control

topsoil: in reclamation, all soil that will support plant growth, but normally the 20 to 30 centimeters of the organically rich top layer

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