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Mountaintop removal mining

Type of surface mining

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Through Summit, Mining and Coal

Overview

Mountaintop removal mining (MTR), also known as mountaintop mining (MTM), is a form of surface mining that involves the topographical alteration and/or removal of a summit, hill, or ridge to access buried coal seams.

The MTR process involves the removal of coal seams by first fully removing the overburden lying atop them, exposing the seams from above. This method differs from more traditional underground mining, where typically a narrow shaft is dug which allows miners to collect seams using various underground methods, while leaving the vast majority of the overburden undisturbed. The overburden from MTR is either placed back on the ridge, attempting to reflect the approximate original contour of the mountain, and/or is moved into neighboring valleys. When excess rock and soil containing mining byproducts are disposed into nearby valleys, the valleys are called "holler fills" or "valley fills".

MTR in the United States is most often associated with the extraction of coal in the Appalachian Mountains. Google Earth Engine and Landsat imagery report the extent of newly mined land from 1985 to 2015 to be 2,900 km2. Considering surface mining sites prior to 1985, the cumulative total of mined land was calculated to be 5,900 km2. Further studies calculated that 12 m2 of mined land produced one metric ton of coal. There are many MTR site locations ranging from Ohio to Virginia. It occurs most commonly in West Virginia and Eastern Kentucky, the top two coal-producing states in Appalachia. At current rates, MTR in the U.S. will mine over 1.4 million acres (5,700 km2) by 2010, an amount of land area that exceeds that of the state of Delaware. More than 500 mountains in the US have been destroyed by this process, resulting in the burial of 3,200 km (2,000 mi) of streams.

Mountaintop removal has been practiced since the 1960s. Increased demand for coal in the United States, sparked by the 1973 and 1979 oil crises, created incentives for a more economical form of coal mining than the traditional underground mining methods involving hundreds of workers, triggering the first widespread use of MTR. Its prevalence expanded further in the 1990s to retrieve relatively low-sulfur coal, a cleaner-burning form, which became desirable as a result of amendments to the U.S. Clean Air Act that tightened emission limits on high-sulfur coal processing.

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