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Tribal Energy and Environmental Information Clearinghouse: Environmental resources for tribal energy development
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Coal Mine Construction and Operation: Development Activities and Resource Requirements

Dragline at the TransAlta Centralia Coal Mine
Dragline at the TransAlta Centralia Coal Mine
Source: Erichwtl
Dragline at the TransAlta Centralia Coal Mine
Source: Erichwtl
Click to enlarge

Potential impacts from coal mining affect the entire project area, but the amount of coal present and the mining method will affect the magnitude of the impacts.

Activities during the construction and mining phase include either surface or underground mining in addition to any facility (e.g., shaft construction) and coal transport system (e.g., access roads, rail lines, pipelines, conveyor systems) construction.

Farrell-Cooper coal mining operation at Bates, Arkansas
Farrell-Cooper coal mining operation at Bates, Arkansas
Source: Arkansas Geological Survey
Farrell-Cooper coal mining operation at Bates, Arkansas
Source: Arkansas Geological Survey
Click to enlarge

The process of strip mining includes clearing the topsoil and stockpile for reclamation, removing the overburden with draglines (also stockpiled), mining the coal seam, and transporting the mined coal with dump trucks or high-capacity conveyor belts. As the mining of the coal seam moves forward, the mined area is reclaimed by replacing and recontouring overburden and replacing topsoil. With an open-pit mine, the mining begins by drilling and blasting waste rock to expose the coal seam, excavating additional overburden, and removing and transporting the coal. The coal is removed one bench layer at a time and the mine continues to get wider and deeper as the mining continues.

Coal Crushing
Coal Crushing
Source: Arkansas Geological Survey
Coal Crushing
Source: Arkansas Geological Survey
Click to enlarge

The process of underground mining includes cutting into the coal deposit and removing it from the coal face through room-and-pillar methods or longwall methods. Room-and-pillar methods can leave up to 50% of the coal in place, due to the remaining pillars that hold up the roof; however some of these pillars can be removed toward the end of the mining operation during the retreat from the mine. For longwall mining, the entire coal face can be removed as hydraulic supports hold up the roof of the mine. Once the coal is removed, the supports can be removed and the roof of the mine is allowed to collapse.

The following factors could affect whether an environmental impact could occur and whether it would be considered an adverse effect:

  • Acreage – The size of the coal seam and the mining method will determine the acreage affected. Some surface mines can be over a mile wide and several hundred feet deep. For surface mines, it is estimated that approximately 25 tons of overburden are removed for every ton of coal mined.

  • Emissions – Fugitive dust emissions would result from land disturbance, vehicular and equipment emissions, volatile organic compounds (VOCs) from storage and use of fuels for equipment.

  • Waste Generation -Significant amount of waste rock and coal refuse would be generated. In the United States, approximately 120 million tons of coal refuse are generated each year. It is estimated that the preparation of coal typically generates wastes that are about 10% of the coal mined. Industrial wastes would be generated including those that are routinely associated with construction-type activities (waste oils, lubricants, and coolants from the on-site maintenance of vehicles and equipment, spent solvents) and solid wastes.

  • Water Needs –Water would be needed for fugitive dust control (depending on local conditions); coal washing at the coal preparation plant (wet method); operation of mining equipment; potable water for the construction crew; and fire contingency supply.

  • Workforce – In 2007, there were 1,374 operating mines in the United States directly employing 81,278 people. The number of workers per mine would depend on project-specific factors, such as the size of the mine and the methodology employed.

  • Time – Coal mines can operate for 50 years, but the length of production is largely dependent upon size of the coal seam and economic and technological conditions.

  • Utility Requirements – Electrical lines would be required to power the mine plant. They would run along access road right-of-ways.