Administrative Rules of Montana
Department 17 - ENVIRONMENTAL QUALITY
Chapter 17.24 - RECLAMATION
Subchapter 17.24.5 - Strip and Underground Mine Reclamation Act: Backfilling and Grading Requirements
Rule 17.24.515 - HIGHWALL REDUCTION
Universal Citation: MT Admin Rules 17.24.515
Current through Register Vol. 6, March 22, 2024
(1) Highwalls must be eliminated and the reduced highwall slope must be no greater than whatever slope is necessary to achieve a minimum long-term static safety factor of 1.3. The department may specify a lesser slope whenever necessary to achieve postmining slope stability. Highwall reduction must be commenced at or beyond the top of the highwall and sloped to the graded spoil bank.
(2) Highwall reduction alternatives may be permitted only to replace bluff features that existed before mining and where the department determines that:
(a)
postmining bluffs are compatible with the proposed postmining land
use;
(b) postmining bluffs are
stable, achieving a minimum long-term static safety factor of 1.3;
(c) similar geometry and function exists
between pre- and postmining bluffs;
(d) the horizontal linear extent of
postmining bluffs does not exceed that of the premining condition;
and
(e) highwalls will be
backfilled to the extent that the uppermost mineable coal seam is buried in
accordance with ARM
17.24.505(1).
AUTH: 82-4-205, 82-4-231, MCA; IMP: 82-4-232, MCA
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