Introduction - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 7

abandonment of dry coal cleaning processes in recent years. The increased use
of water to control dust in underground mines, and the increased efficiency of
wet cleaning methods have continued the sharp decline in dry coal cleaning
methods.
Coal preparation (colloquially referred to as "washing") separates
noncombustible materials from coal. Processing the run-of-mine coal may
include: removing extraneous materials, crushing, sizing, blending coal from
several locations, and concentration. A coal preparation plant separates the
material it receives into a product stream and a reject stream, which may be
further divided into coarse and fine refuse streams. Depending on the source, 20
to 50 percent of the material delivered to a coal preparation plant may be
rejected (Leonard, 1991). One of the reject streams is slurry, a blend of water,
coal fines, silt, sand, and clay particles, which is most commonly disposed of in
an impoundment.
COAL REFUSE IMPOUNDMENTS IN THE UNITED STATES
Coal refuse disposal impoundments are constructed for the permanent
disposal of any coal, rock, and related material removed from a coal mine in the
process of mining. Standard classification of coal slurry impoundments includes
the following:
• Active— In operation and receiving slurry.
• Inactive— Not in operation or receiving slurry. Inactive impoundments may
receive slurry in the future, becoming active again, and therefore have not
been closed permanently.
• Abandoned— Not in operation and closed. These impoundments usually
have been filled to capacity and have been closed and reclaimed.
• Grandfathered or "Pre-law"— Not in operation since promulgation of the
1977 Surface Mining Control and Reclamation Act (SMCRA) regulation.
These impoundments are reclaimed under the Abandoned Mine Lands
Program.
As of August 2001, MSHA oversees 713 active fresh-water and slurry
impoundments in the United States (T.Bentley, Mine Safety and Health
Administration, personal communication, 2001). Most coal waste
impoundments in the United States are found in the East, predominantly in
West Virginia, Pennsylvania, Kentucky, and Virginia. The thicker Western coal
seams being mined now contain fewer in-seam partings and out-of-seam