Fill Construction and Underground Coal Mining

Underground mining techniques, which account for the majority of West Virginia's coal production, utilize machinery to drive tunnels under the surface of the land. These tunnels are situated in coal seams so as the machinery advances further underground, coal is removed. Using a combined system of vehicle haulage and conveyor belts, the coal extracted from teh seam is transported to the surface.[1]  In underground mining, it is impossible to separate coal from rock partings that lie above, within or below the coal seam. This inherent material is removed along with the coal and transported to the surface. In order to provide a saleable product that is free from these impurities, these rock partings are removed from the coal in a preparation plant using combined mechanical and chemical separation procedures:

Figures B.1 and B.2 are photographs of typical preparation plants.

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Figure B-1

Coal Preparation Plant and Railroad Loadout

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Figure B-2

Coal Preparation Plant 

Once removed from the coal, these partings, now referred to as coal refuse, are placed in engineered and permitted structures referred to as refuse fills. Figure B-3 is a photograph of a coal refuse fill. 

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Figure B-3 

Coal Refuse Fill at an Underground Mining Operation in West Virginia

In some cases the coal refuse is used to construct an embankment of a dam that serves as a source of water used in the coal preparation plant process.  Known as coal refuse dams, these structures along with refuse fills, are subject to the requirements of five separate regulatory programs and are designed to the strictest engineering standards to assure their stability and safety. In addition to the CWA section 404 permitting and mitigation requirements, these structures are permitted and reviewed by the federal Mine Safety and Health Administration, the West Virginia Department of Environmental Protection (both the mining and water resources programs), and the federal Office of Surface Mining Reclamation and Enforcement.  Figure B-4 is a photograph of an active coal refuse impoundment.  Figures B-5 and B-6 are photographs of a coal refuse impoundments that are being reclaimed. Note that the face of the embankment has been seeded and the impounding capacity of the structure is being eliminated. 

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Figure B-4

Active Coal Refuse Impoundment

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Figure B-5

Coal Refuse Impoundment Being Reclaimed. The Face of the Embankment is Seeded and the Impounding Capacity of the Structure is being Eliminated

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Figure B-6

Coal Refuse Impoundment in Late Reclamation. Tree Growth is Evident on the Face of the Embankment.

Most, if not all of the coal removed using underground mining techniques must be cleaned in the preparation plant process before it is shipped to consumers, making coal refuse fills and dams vital to the continued existence of the underground mining industry in West Virginia and the country: 

Whatever is not shipped to a [coal] customer from a preparation plant goes into a refuse disposal facility.  It is not unusual for a plant to handle over 1,000 tons per hour of coal refuse.  An operation of that magnitude must have access to a large disposal site within relatively close proximity to the plant.  Without the ability to construct valley fills for coal refuse disposal, deep mining in West Virginia would become virtually impossible.[4]         

In addition to the required refuse structures, underground mining operations in West Virginia fall under the jurisdiction of the section 404 program because of the pre-mining construction activities that are necessary to provide access to the coal seam.  The installation of an underground mine generally requires the construction of a valley fill as rock and earth is removed from the mountainous area and a flat area, or “bench” is created that allows access to the coal seam and provides an area for critical underground mining infrastructure such as bathhouses, electrical power installations, access roads and underground ventilation facilities:

Development of underground mine portal facilities in southern West Virginia often requires the construction of valley fills for permanent disposal of excess material and for temporary storage of mine face-up spoil. A typical small deep mine installation includes a portal bench excavation, a stockpile bench cut into the hillside, and a valley fill as close to possible to provide spoil storage and to serve as a parking and supply storage area. [5]

Underground mining development involves excavating rock and soil on the surface to expose the coal seam and to provide access for people, equipment and ventilation for the underground mining operation.  This process is referred to as “facing up.”  In steep terrain, excavated material from these “face-up” areas may result in small fills if the excavation is limited to providing coal seam access, or larger fills if facilities such as miners’ bathhouses, office buildings, and coal storage or coal preparation areas are needed. [6]              

In addition to the face-up areas, underground mines require section 404 permits for the construction of in-stream ponds to control the runoff from the mining area:  

In order to minimize sedimentation and comply with CWA [Clean Water Act] or state effluent standards, an operator of a surface or underground mine may need to place sediment control structures or ponds in streams below the mine. [7] 

Figure B-7 is a photograph of an underground mining complex in West Virginia.  This particular operation accesses the coal seam with a slope entry.  As the photo indicates, section 404 authorization was required to provide room for the deep mine slope, supporting facilities such as the equipment shop, bathhouse, ventilation fans and raw coal staging area.  In this particular case a large culverted fill was constructed to provide the underground mine bench. 

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Figure B-7

Underground Mining Operation in Southern West Virginia Showing Surface Facilities that Necessitate Stream Impacts and Section 404 Authorization