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Appendix C
Glossary
ABANDONED IMPOUNDMENT An impoundment that is not in operation
and is closed. It has been filled to capacity and reclaimed.
ACTIVE IMPOUNDMENT An impoundment that is in operation and
. .
receiving s urry.
AQUITARD A low permeability geologic horizon that restricts the migration
of water under ordinary hydraulic gradients.
ASH The inorganic residue after burning, esp. of coal. The term is also used
informally to refer to the non-coal mineral matter associated with coal
that will become ash after combustion at the power plant. Coal with
more ash has less heating value.
AUGER Mining equipment used to extract coal by boring horizontal holes
into the coal seam. Auger mining is conducted from the outcrop most
typically in conjunction with contour surface mining.
BARRIER PILLAR Block of coal left in place in an underground mine for
safety and stability purposes and to prevent water influx.
BASIN (as used in this report) Area of existing contours within an
impoundment that excludes the embankment; the area covered by slurry
and water; both the floor and the walls of the pool behind the embank-
ment.
BEACH (as used in this report) The subaerial accumulation of the coarser
fraction deposited Tom slurry.
BED SEPARATION The parting of strata along upper and/or lower contacts
due to subsidence.
BLACK WATER Water mixed with fine coal refuse.
BLIND FLUSHING Injection into an underground mine whose access has
been obstructed.
BLOW-IN Opposite of blow-out; catastrophic failure resulting from water
pressure building up on the surface of an outcrop coal barrier; the
material "blows in" to the underground workings from the surface.
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COAL WASTEIMPOUNDMENTS
BLOW-OUT Opposite of blow-in; catastrophic failure resulting Tom build-
up of underground water pressure against an outcrop coal barrier.
Material "blows out" from underground workings to the surface.
BONY COAL Coal high in mineral content, usually clay shale particles.
BREAKTHROUGH Catastrophic failure/opening of mine working along a
fracture, joint, bedding plane, or other zone of weakness.
BTU (BRITISH THERMAL I5NIT) Heating value for a unit weight of coal.
The heat needed to raise one pound of water one degree Fahrenheit.
BULKHEAD A seal constructed to prevent water from entering or exiting
an area of the mine. Barrier design and construction is based upon the
amount of water pressure (water head, expressed in feet) that will be
exerted against the bulkhead.
CLOSED-LOOP SURVEY Method of establishing He accuracy of a mine
survey by conducting a loop traverse to the point of beginning. The
accuracy is measured in terms of a ratio of feet of error to feet of traverse,
e.g., 1:5000 indicates an error of 1 foot over a 5000-foot traverse.
COMPRESSIVE STRESS Stress that pushes together material on opposite
sides of a real or imaginary plane.
CONTROLLED PLACEMENT (as used in this report) Injection of coal
waste slurry into an underground mine that has been mapped and
inspected, whose volume is known, and in which bulkheads may be
built to control the direction and extent of flow.
DAM An artificial barrier or wall constructed across a watercourse to
confine flowing water for a variety of purposes, such as creating a pond
or lake for storage of water; creating a hydraulic head that can used to
generate power; controlling floods; or retention of debris.
DEPTH-TO-MINED-HEIGHT RATIO Ratio of the depth of the coal seam
to the mined-height, or "effective thickness," of the mined seam.
DOWNSTREAM CONSTRUCTION EMBANKMENT A method of staged
embankment construction where the embankment centerline is moved
downstream with subsequent embankment raises.
EMBANKMENT has used in this report) A linear engineered structure
extending above the natural ground surface that retains fine coal slurry
waste material; it is built with earthen materials or coarse coal refuse
(waste material).
EXTENSOMETER An instrument for measuring changes caused by stress
in a linear dimension of a body.
FACTOR OF SAFETY A quantitative measure of the ratio of available
strength to applied force. For slope stability, factor of safety is the ratio
of forces resisting slope movement to forces causing slope movement.
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APPENDIX C
215
FINES An informal term referring to fine particles, either product or waste,
resulting from processing and preparation; usually less than 100 mesh
(150 micrometers) and greater than 325 mesh (45 micrometers).
FOOTPRINT OF THE EMBANKMENT The area of natural ground to be
covered by the embankment.
FREEBOARD The difference in elevation between the embankment crest or
spillway invert (bottom) and the water pool elevation in an impound-
ment.
FRENCH DRAIN Small underground channel filled with permeable materials
used to convey water passively.
GRANDFATHERED/PRE-LAW IMPOUNDMENT An impoundment that
has not been 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.
HYDRAULIC HEAD The height of the free surface of a body of water
above a given subsurface point; or, pressure against the dam from the
weight of the slurry (as used in this reports.
IMPOUNDMENT (as used ire this report) The entire structure used for coal
slurry waste disposal, including the embankment, basin, beach, pool,
and slurry.
INACTIVE IMPOUNDMENT An impoundment that is not in operation or
receiving slurry. Inactive impoundments may receive slurry in the future,
becoming active again, and therefore have not been closed permanently.
JOENT A fracture or parting in rock along which no displacement has
occurred.
LIQUEFACTION The transformation of a solid material, such as loosely
packed sediment or cohesionless soil, into a fluid mass due to increased
pore pressure and reduced effective stress.
LOADING Mass and other vertical stresses applied to structure.
MOISTURE CONTENT (as used in this report) The percentage of water in
a waste slurry. Calculated as the weight of water divided by the weight
of the dried solids multiplied by 100.
MONITORING Observing, regulating, and evaluating a system to ensure
that it is operating properly.
NORTH AMERICAN DATUM 27 (NAD27) Mapping coordinate standards
established in 1927, measured in feet.
NORTH AMERICAN DATUM 83 (NAD83) Mapping coordinate standards
established in 1983, measured in meters.
OUTCROP The intersection between a geologic formation (e.g., coal seam)
and the Earth's surface.
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216
COAL WASTEIMPOUNDMENTS
OUTCROP BARRIER (Boundary/Perimeter Pillar) Distance between the
coal outcrop and the furthest extent of underground mine workings in
the direction of the outcrop.
PACKERS Plugs that are used to isolate fluid under pressure in a specific
segment of pipe in a hole.
PARTINGS Thin sedimentary layers that follow a surface of separation
between thicker units of rock.
PERMEABILITY The capacity of a porous medium to permit flow of a
given fluid.
PHREATIC SURFACE The groundwater interface or a zone of saturation
where the water pressure is equal to atmospheric pressure.
PIPING Seepage through embankments, which can lead to failure by internal
erosion.
POOL Area of free-standing water separated from the slurry discharge point
by the beach; it may contain a low percentage of fines and ultra-f~nes,
and suspended and unconsolidated solids.
PROBABLE MAXIMUM PRECIPITATION The theoretical, greatest depth
of precipitation for given duration that is possible over a particular
drainage basin.
P-WAVE Compressional seismic waves; sound waves; they travel faster than
other seismic waves.
QUADRANGLE MAP, 7/2-MINUTE GEOLOGICAL Topographic and
geologic maps produced by the U.S. Geological Survey. The maps
depict an area of 7/ minutes of latitude and longitude.
RAISE (as used in this reports The construction of an embankment in a
staged manner so that the embankment crest is higher in elevation than
the previous stage.
REFUSE (OR GOB) PILE Area where coarse waste material (larger than 28
mesh, 800 micrometers) is disposed.
RUN-OF-M[NE Raw mined material, unaltered from what is transported out
of the mine.
SIDE SLOPE Natural embankment.
SLIMES Material in the waste stream smaller than 325 mesh (45 micro-
meters) and composed mainly of clay or clay-like particles; have high
moisture content or the ability to retain water.
SLURRY A mixture of water and solids (less than 28 mesh, 800 micrometer,
particle size) prepared for handling as a liquid for processing and disposal.
SOLIDS CONTENT (as used in this reports The percentage of solids in a
waste slurry.
SPAD A flat spike, hammered into a wooden plug, anchored in a hole drilled
into the mine ceiling from which is threaded a plumbline. The sped is an
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APPENDIX C
217
underground survey station similar to the use of stakes in marking
survey points on the surface. A brass tag permanently attached to the
mine roof.
STACKING Disposing of dewatered coal waste in "stacks" or layers (from
4-6 inches to 1-3 feet in thickness) piled on top of each other without an
embankment.
STARTER DAM The initial embankment constructed as the first stage of a
staged embankment construction system.
STRATA Multiple layers of sedimentary rock.
SURFACE WAVES Seismic waves that travel only near the surface of the
earth; they travel about 90 percent as fast as S-waves.
S-WAVE A wave reflecting shear motion, with oscillation perpendicular to
the direction of propagation.
TAILINGS Fine particle waste streams from either coal preparation or other
mineral processing plants.
TAILINGS DAM (as used in this report) A structure constructed to contain
fine particle waste streams from other mineral processing plants.
TENSILE STRESS A normal stress causing separation across the plane on
which it acts.
TOE DRAIN A zone of permeable materials constructed at the downstream
toe of an embankment to collect and convey water from the downstream
region of the embankment.
ULTRA-FINES Fine particles, either product or waste, resulting from the
processing or preparation of any mineral; particles are smaller than 325
mesh (45 micrometers).
UPSTREAM CONSTRUCTION DAM A method of staged embankment
construction where the embankment centerline is moved upstream with
subsequent embankment raises.
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Representative terms from entire chapter:
water pressure