Glossary - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 199

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).

FOOT-
PRINT OF
THE EM-
BANKMENT

The area of natural ground to be covered by the embankment.

FREE-
BOARD

The difference in elevation between the embankment crest or spillway
invert (bottom) and the water pool elevation in an impoundment.

FRENCH
DRAIN

Small underground channel filled with permeable materials used to convey
water passively.

GRAND-
FATHERED
/PRE-LAW
IM-
POUND-
MENT

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.

HY-
DRAULIC
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 report).

IM-
POUND-
MENT

(as used in this report) The entire structure used for coal slurry waste
disposal, including the embankment, basin, beach, pool, and slurry.

INACTIVE
IM-
POUND-
MENT

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.

JOINT A fracture or parting in rock along which no displacement has occurred.

LIQUE-
FACTION

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.

MONITOR-
ING

Observing, regulating, and evaluating a system to ensure that it is operating
properly.

NORTH
AMERI-
CAN DA-
TUM 27
(NAD27)

Mapping coordinate standards established in 1927, measured in feet.

NORTH
AMERI-
CAN DA-
TUM 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.