Administrative Rules of Montana
Department 17 - ENVIRONMENTAL QUALITY
Chapter 17.24 - RECLAMATION
Subchapter 17.24.6 - Strip and Underground Mine Reclamation Act: Transportation Facilities, Use of Explosives, and Hydrology
Rule 17.24.642 - PERMANENT IMPOUNDMENTS AND FLOOD CONTROL IMPOUNDMENTS
Current through Register Vol. 6, March 22, 2024
(1) Permanent impoundments are prohibited unless constructed in accordance with ARM 17.24.504 and 17.24.639 and have open-channel spillways that will safely discharge runoff resulting from a 100-year, six-hour precipitation event, assuming the impoundment is at full pool for spillway design or larger event specified by the department. The department may approve a permanent impoundment upon the basis of a demonstration that:
(2) All permanent impoundments must meet the design and performance requirements of ARM 17.24.639.
(3) All permanent impoundments must be routinely maintained during the mining operations. Ditches and spillways must be cleaned.
(4) All permanent impoundments must be inspected and certified to the department by a qualified licensed professional engineer, immediately after construction and annually thereafter, as having been constructed and maintained to comply with the requirements of this section. Inspection reports must be submitted until phase IV bond release. Certification reports must be submitted to the department annually, either concurrently with the annual report (ARM 17.24.1129) or with the second semi-annual hydrology report (ARM 17.24.645(8) and 17.24.646(2)). The operator shall retain a copy of each report at or near the minesite. Certification reports must include statements on:
(5)
(6) Permanent impoundments and flood control impoundments with embankments meeting the size or other criteria of 30 CFR 77.216 (a) or the Class B or C criteria for dams in TR-60 must be routinely inspected by a qualified licensed professional engineer or by someone under the supervision of a qualified licensed professional engineer, in accordance with 30 CFR 77.216-3.
(7) Plans for any enlargement, reduction in size, reconstruction, or other modifications of permanent impoundments and flood control impoundments must be submitted to the department and must comply with the requirements of this subchapter. Except where a modification is required to eliminate an emergency condition constituting a hazard to public health, safety, or the environment, the modification must not be initiated until the department approves the plans.
AUTH: 82-4-205, MCA; IMP: 82-4-231, MCA