Current through Register Vol. 6, March 22, 2024
(1) Each
application must include a general plan for each proposed sedimentation pond
and water impoundment within the proposed mine plan areas.
(a) Each general plan must:
(i) be prepared by, or under the direction
of, and certified by a qualified licensed professional engineer, experienced in
designing impoundments;
(ii)
contain a description, map, and cross-section of the structure and its
location;
(iii) contain preliminary
hydrologic and geologic information required to assess the hydrologic impact of
the structure;
(iv) contain a
survey describing the potential effect on the structure from subsidence of the
subsurface strata resulting from past underground mining operations if
underground mining has occurred; and
(v) contain a certification statement which
includes a schedule setting forth the dates that any detailed design plans for
structures that are not submitted with the general plan will be submitted to
the department. The department must have approved, in writing, the detailed
design plan for a structure before construction of the structure
begins.
(b) Each detailed
design plan for a structure that meets or exceeds the size or other criteria of
the mine safety and health administration,
30 CFR
77.216 (a), or meets the Class B or C
criteria for dams in USDA soil conservation service Technical Release No. 60
(210-VI-TR60, October 1985, as revised through January 1991), "Earth Dams and
Reservoirs", (TR-60) must:
(i) be prepared
by, or under the direction of, and certified by a qualified licensed
professional engineer with assistance from experts in related fields such as
geology, surveying, and landscape architecture. The certifying engineer must
have experience designing impoundments;
(ii) include any geotechnical investigation,
design, and construction requirements for the structure;
(iii) include a stability analysis of the
structure. The stability analysis must contain, but not be limited to, strength
parameters, pore pressures, and long-term seepage conditions. It must contain a
foundation investigation, as well as any necessary laboratory testing of
foundation materials, to determine the design requirements necessary to meet
and to show that the design will meet the standards of ARM
17.24.639(8) for
foundation stability. The plan must also contain a description of each
engineering design assumption and calculation with a discussion of each
alternative considered in selecting the specific design parameters and
construction methods;
(iv) describe
the operation and maintenance requirements for each structure; and
(v) describe the timetable and plans to
remove each structure, if appropriate.
(c) Technical Release No. 60 (TR-60) is
available for inspection at the Department of Environmental Quality, 1520 East
6th Avenue, Helena, MT 59601.
(d)
Each detailed design for a structure that does not meet the size or other
criteria of 30 CFR
77.216 (a) or the criteria for Class B or C
dams in TR-60, must:
(i) be prepared by, or
under the direction of, and certified by a qualified licensed professional
engineer. The certifying engineer must have experience in designing
impoundments;
(ii) include any
design and construction requirements for the structure, including any required
geotechnical information;
(iii)
include appropriate information on the foundation conditions of the structure
to determine the design requirements necessary to meet and to show that the
design will meet the standards of ARM
17.24.639(8) for
foundation stability;
(iv) describe
the operation and maintenance requirements for each structure; and
(v) describe the timetable and plans to
remove each structure, if appropriate.
(2) Sedimentation ponds, whether temporary or
permanent, must be designed in compliance with the requirements of ARM
17.24.639. Impoundments meeting the criteria of
30 CFR
77.216 (a), must comply with the requirements
of 30 CFR
77.216-1 and
77.216-2, and must be submitted to
the mine safety and health administration.
(3) Permanent impoundments must be designed
to comply with ARM
17.24.642, and the requirements of
the mine safety and health administration,
30 CFR
77.216-1 and
77.216-2.
(4) Dams and reservoirs impounding 50
acre-feet or more either singly or in series within the same watershed, may
require a construction and operating permit as required in the Dam Safety Act.
For purposes of the Dam Safety Act, capacity is measured to the crest of the
dam. Operators must contact the department of natural resources and
conservation to determine what requirements must be met.