17.24.315    PLAN FOR PONDS AND EMBANKMENTS

(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.

 

History: 82-4-205, MCA; IMP, 82-4-222, 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, 1999 MAR p. 811, Eff. 4/23/99; AMD, 2004 MAR p. 2548, Eff. 10/22/04; AMD, 2024 MAR p. 255, Eff. 2/10/24.