17.24.832 AUGER MINING: SPECIFIC PERFORMANCE STANDARDS
(1) Any auger mining associated with strip mining operations must be conducted to maximize recoverability of mineral reserves remaining after the mining operations are completed. Each operator conducting auger mining operations shall leave areas of undisturbed coal to provide access for removal of those reserves by future underground mining activities, unless the department determines that the coal reserves have been depleted or are limited in thickness or extent to the point that it will not be practicable to recover the remaining coal reserves. The department shall make such determination only upon presentation of appropriate technical evidence by the operator.
(2) Undisturbed areas of coal must be left in unmined sections that:
(a) are a minimum of 250 feet wide at any point between each group of auger openings to the full depth of the auger hole;
(b) are no more than 2,500 feet apart, measured from the center of one section to the center of the next section, unless a greater distance is set forth in the permit application under ARM 17.24.326 and approved by the department; and
(c) for multiple seam mining, have a width of at least 250 feet plus 50 feet for each subjacent workable coal seam. The centers of all unmined sections must be aligned vertically.
(3) An auger hole must not be located closer than 500 feet in horizontal distance from any abandoned or active underground mine workings, except as approved in accordance with ARM 17.24.516.
(4) If the operation involves stripping for the purpose of augering, the requirements of ARM 17.24.501(6) (c) for the purpose of backfilling and grading must be followed.
(5) In order to prevent pollution of surface and ground water and to reduce fire hazards, each auger hole, except as provided in (6) , must be plugged to prevent the discharge of water from the hole and access of air to the coal, as follows:
(a) each auger hole discharging water containing toxic-forming or acid-forming material must be plugged within 72 hours after completion by backfilling and compacting noncombustible and impervious material into the hole to a depth sufficient to form a water-tight seal, if possible. If sealing within 72 hours is not possible, the discharge must be treated commencing within 72 hours after completion to meet applicable effluent limitations and water quality standards under ARM 17.24.633 until the hole is properly sealed;
(b) each auger hole discharging water not containing acid-or toxic-forming materials must be sealed with an impervious noncombustible material, as contemporaneously as practicable with the augering operation, as approved by the department; and
(c) each auger hole not discharging water must be sealed as in (5) (a) to close the opening as contemporaneously as practicable with the augering operation.
(6) An auger hole need not be plugged if the department finds that:
(a) impoundment of the water that would result from plugging the hole may create a hazard to the environment or public health or safety; and
(b) drainage from the auger hole will not pose a threat of pollution to surface water and will comply with the requirements of ARM 17.24.631 and 17.24.633.
(7) The department shall prohibit auger mining, if it determines that:
(a) adverse water quality impacts cannot be prevented or corrected;
(b) fill stability cannot be achieved;
(c) the prohibition is necessary to maximize the utilization, recoverability, or conservation of the solid fuel resources; or
(d) subsidence resulting from auger mining may disturb or damage powerlines, pipelines, buildings, or other facilities or does not comply with the subsidence protection requirements of ARM 17.24.901 and 17.24.911.
History: 82-4-204, MCA; IMP, 82-4-231, 82-4-232, 82-4-233, MCA; NEW, 1980 MAR p. 725, Eff. 4/1/80; AMD, 1989 MAR p. 30, Eff. 1/13/89; TRANS, from DSL, 1996 MAR p. 3042; AMD, 2004 MAR p. 2548, Eff. 10/22/04.