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Mountaintop removal mining

technology Maturity 11-13 Next article →

Mountaintop removal mining, often called MTR or mountaintop mining, is a specific type of surface mining. This process targets the summit or the summit ridge of a mountain to reach coal. Instead of digging deep tunnels, miners remove the land sitting above the coal to get to it. This layer of rock and soil is known as the overburden. MTR is considered a safer method than traditional underground mining. This is because the coal seams are accessed from above rather than through deep, dark shafts.

The mechanism of MTR involves several precise steps. First, the land is deforested, and the resulting lumber is sold or burned. Next, miners use explosives to blast away the overburden. These blasts can remove up to 400 vertical feet of the mountain to expose the coal seams. Once the seams are visible, machines like front-end loaders or excavators remove the coal. This coal is then transported to a processing plant. Because coal exists in multiple geologically stratified seams, miners can repeat this blasting process many times. This can increase the mine depth by hundreds of extra feet.

EPA Mountaintop Removal2
EPA Mountaintop Removal2

There are two main ways to handle the excess rock and soil, known as spoils. One method is to place the material back on the ridge. This attempts to reflect the approximate original contour of the mountain. The second method involves moving the excess material into neighboring valleys. When this happens, the resulting areas are called "valley fills" or "holler fills."

Mountaintop removal mine in Pike County, Kentucky
Mountaintop removal mine in Pike County, Kentucky

These valley fills can change the local environment. They can bury streams that were originally in the valley. They can also cause acid mine drainage, which increases concentrations of sulfate, iron, aluminum, and manganese in surrounding waters.

This mining method has a distinct history in the United States. MTR has been practiced since the 1960s. It became much more common following the oil crises of 1973 and 1979. These crises created a need for more economical coal mining. MTR was cheaper than traditional underground mining, which required hundreds of workers. In the 1990s, the practice expanded further due to the U.S. Clean Air Act. These law amendments tightened emission limits on high-sulfur coal. This made low-sulfur coal, which is a cleaner-burning form, much more desirable.

Hobet Mountaintop mine West Virginia 1984-09-18 (cropped)
Hobet Mountaintop mine West Virginia 1984-09-18 (cropped)

The scale of MTR is quite large, particularly in the Appalachian Mountains. This region includes states from Ohio to Virginia. West Virginia and Eastern Kentucky are the two largest coal-producing states in Appalachia. In 2006, MTR provided 30 percent of the coal mined in West Virginia. Data from Google Earth Engine and Landsat shows that 2,900 square kilometers of land were newly mined between 1985 and 2015. When adding land mined prior to 1985, the cumulative total was 5,900 square kilometers. More than 500 mountains in the U.S. have been destroyed by this process.

Hobet Mountaintop mine West Virginia 2009-06-02
Hobet Mountaintop mine West Virginia 2009-06-02

After mining is complete, the land must undergo reclamation. The Surface Mining Control and Reclamation Act of 1977 (SMCRA) regulates these activities. The law lists the restoration of land and water resources as a priority. Companies are supposed to set aside topsoil to use during this stage. However, companies are often granted waivers if adequate topsoil is not naturally present. They may instead use a "topsoil substitute." Once the ground is prepared, grass seed is spread with fertilizer and mulch. Some land is reclaimed for pastures or economic development. Other groups, like the Appalachian Regional Reforestation Initiative, work to grow hardwood trees.

Tall ironweed (25137682634)
Tall ironweed (25137682634)

Understanding the health of these ecosystems often involves looking at specific biological signs. For example, mayflies are abundant in the Appalachian Mountain region. These insects are highly sensitive to water quality. Their immature forms require unpolluted water to survive. Because valley fills and acid mine drainage alter water chemistry, mayflies serve as an indicator species. Scientists can use these populations to monitor how well restoration efforts are working. This helps researchers determine the most effective ways to protect local wildlife and restore the natural habitat.

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File:MTR1.jpg
MTR1.jpg
File:Mountaintop removal mine in Pike County, Kentucky.jpg
Mountaintop removal mine in Pike County,...
File:EPA Mountaintop Removal2.gif
EPA Mountaintop Removal2.gif
File:Hobet Mountaintop mine West Virginia 1984-09-18 (cropped).jpg
Hobet Mountaintop mine West Virginia...
File:Hobet Mountaintop mine West Virginia 2009-06-02.jpg
Hobet Mountaintop mine West Virginia...
File:Tall_ironweed_(25137682634).jpg
Tall_ironweed_(25137682634).jpg
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