Project Phases and Activities
Impacts from a coal mine can occur from activities during each phase of the project: site evaluation and exploration, construction and mining, and decommissioning and reclamation.
What Activities Occur During the Site Evaluation and Exploration Phase?
Before a coal mine can be planned and built, a number of tests and surveys must be conducted to make sure the project is economically viable, technically feasible, and environmentally sound. These activities include mapping, drilling (to obtain geological samples), and geophysical exploration. Geophysical exploration methods can include aerial photography, airborne geophysical surveys (magnetic, radiometric, and electromagnetic); on-the-ground geophysical surveys (drill-hole logging; electrical, magnetic, electromagnetic, radiometric, gravimetric, and refraction-seismic surveys; induced polarization surveys using exposed electrodes). Reclamation of exploratory areas that will not be part of the project area would occur during this phase. Field surveys for identifying cultural resources, paleontological resources, and ecological resources (habitats, species) in the project area should also be conducted during this phase.
What Activities Occur During the Construction and Mining Phase?
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.
The process of strip mining includes clearing the topsoil and stockpiling it for reclamation, removing and stockpiling the overburden, mining the coal seam, and transporting the mined coal with dump trucks or high-capacity conveyor belts to a preparation plant. 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 (terracing) and the mine continues to get wider and deeper as the mining continues.
The process of underground mining includes cutting into the coal deposit and removing it from the coal face through room-and-pillar methods using a continuous mining machine, or through longwall methods using a longwall cutting machine. In either method, once the coal is removed, the supports or pillars can be removed and the roof of the mine is allowed to collapse.
What Activities Occur During the Decommissioning and Reclamation Phase?
Decommissioning of a coal mine would include removal of structures, conveyor systems, and rail lines, if used, and the filling in of the mine area. Reclamation of the mine site and access roads, including recontouring and revegetation, would mitigate some impacts, such as soil erosion, habitat fragmentation, and visual impacts.