17.24.501 GENERAL BACKFILLING AND GRADING REQUIREMENTS
(1) Backfilling and grading of the disturbed area must be completed prior to removal of necessary reclamation equipment from the area of operation.
(2) Overburden and parting materials which are not conducive to revegetation techniques, establishment, and growth must not be left on the top nor within eight feet of the top of regraded spoils nor at the surface of any other affected areas, unless the applicant demonstrates to the department's satisfaction that a lesser depth will provide for reclamation consistent with the Act. The department may require that problem materials be placed at a greater depth.
(3)(a) Backfilled material must be placed to minimize erosion and sedimentation of undisturbed and reclaimed areas both on and offsite, water pollution, adverse effects on ground water, other offsite effects, and to support the approved postmining land use.
(b) Backfilled materials must be selectively placed and compacted wherever necessary to prevent leaching of acid, acid-forming toxic, or toxic-forming materials into surface or subsurface waters and wherever necessary to ensure the stability of the backfilled materials. The method and design specifications for placing and compacting such materials must be approved by the department.
(4) All final grading on the area of land affected must be to the approximate original contour of the land in accordance with 82-4-232(1), MCA.
(a) The operator shall transport, backfill, and compact to ensure compliance with (3)(b) and ARM 17.24.505, and grade all spoil material as necessary to achieve the approximate original contour. Highwalls must be reduced or backfilled in compliance with ARM 17.24.515(1), or reclaimed using approved highwall reduction alternatives in compliance with ARM 17.24.515(2).
(b) Cut-and-fill terraces may be used only in those situations expressly identified in and in compliance with ARM 17.24.502.
(c) The postmining graded slopes must approximate the premining natural slopes in the area.
(d) Depressions must be eliminated, except as provided in ARM 17.24.503(1).
(5) The disturbed area must be blended with surrounding and undisturbed ground to provide a smooth transition in topography.
(6) Backfilling and grading must be kept current with mining operations. To be considered current, backfilling and grading must meet the following requirements, unless otherwise approved by the department upon adequate written justification and documentation provided by the operator:
(a) On lands affected by area strip mining, there must not be more than four consecutive spoil ridges present in any location.
(b) Backfilling and grading must be completed within two years after coal removal from each pit has been concluded. For the purpose of this provision, "each pit" means any continuous dragline pass within a particular permit area.
(c) Backfilling and grading of other excavations must be kept current as departmental directives dictate for each set of field circumstances.
(d) All backfilling and grading must achieve the approved postmining topography.
(7) The operator shall notify the department, in writing, upon detection of grading problems that would result in topography not consistent with the approved postmine topography.
History: 82-4-204, 82-4-231, MCA; IMP, 82-4-231, 82-4-232, MCA; NEW, 1980 MAR p. 725, Eff. 4/1/80; AMD, 1989 MAR p. 30, Eff. 1/13/89; AMD, 1990 MAR p. 936, Eff. 5/18/90; TRANS, from DSL, 1996 MAR p. 2852; AMD, 1999 MAR p. 811, Eff. 4/23/99; AMD, 2004 MAR p. 2548, Eff. 10/22/04; AMD, 2012 MAR p. 737, Eff. 4/13/12.