Maryland Code, Environment § 15-601

(a) In this subtitle the following words have the meanings indicated.

(b) “Abandoned” means an operation from which coal has not been removed for a six-month period.

(c) “Affected area” means: (i) the land within the permit area from which coal is removed and which is occupied by pillars; (ii) all land adjacent to the mine openings utilized by the operator; and (iii) off-site disposal areas.

(d) “Completed” means an operation where backfilling, sealing, revegetation, and other requirements of the permit have been accomplished.

(e) “Deep mining” means the extraction of coal through underground mining methods, including gaining access to the coal deposits by means of vertical or inclined shafts, by drift mining from the coal outcrop, or by other means that do not involve the stripping away of overburden to expose the deposit.

(f) “Mine opening sealing” means adequate sealing of a mine so that discharge from the mine is not or will not become injurious to animal or aquatic life or to use of water for domestic or industrial consumption or recreation or does not or will not violate water quality or effluent standards.

(g) “Opening” means a passage into a coal bed that is used for haulage, traveling ways, ventilation, or removal or introduction of water.

(h) “Operator” means any person, partnership, or corporation who removes or intends to remove more than 250 tons of coal from the earth by deep coal mining within 12 consecutive calendar months in any one location.

(i) “Subsidence” means the sinking or settling of a land surface area from beneath which coal has been extracted.