(1) To the extent that coal processing waste is not proposed for backstowing, it must be demonstrated to the satisfaction of the department that valid physical, economic, safety, environmental or other reasons exist for not doing so. Coal processing waste to be returned to underground mine works must be disposed of in accordance with a program approved by the department and the mine safety and health administration.

(2) All coal processing waste that is not backstowed must be hauled or conveyed and placed in new and existing disposal areas approved by the department. These areas must be within a permit area.

(3) Coal processing waste may be disposed of in head-of-hollow or valley fill configurations, including in an underground development waste fill, if the processing waste is:

(a) placed in accordance with (6) through (10);

(b) demonstrated to be non-toxic, non-acid-forming, and otherwise nondeleterious or disposed of in accordance with ARM 17.24.505; and

(c) demonstrated to be consistent with the design stability of the fill.

(4) Coal processing waste materials from activities located outside a permit area, such as those activities at other mines or abandoned mine waste piles, may not be disposed of in the permit area unless it can be demonstrated that:

(a) disposal will be conducted in accordance with ARM 17.24.510; and

(b) there will be no instability of the disposal area or the fill.

(5) (a) All coal processing waste disposal areas must be inspected, on behalf of the operator, by a qualified and licensed professional engineer, in accordance with ARM 17.24.924 and the additional requirements of this section.

(b) Inspection must occur at least quarterly, beginning within seven days after the preparation of the disposal area begins, and be made in accordance with the same critical construction period schedule as contained in ARM 17.24.924(18)(b). The department may require more frequent inspection based upon an evaluation of the potential danger to the health or safety of the public and the potential harm to land, air and water resources.

(c) Inspections must include such observations and tests as may be necessary to evaluate the potential hazards to human life and property, to ensure that all organic material and soil have been removed and that proper construction and maintenance are occurring in accordance with the plan submitted under ARM 17.24.930 and approved by the department.

(d) The inspector shall consider steepness of slopes, seepage, and other visible factors which could indicate potential failure, and the results of failure with respect to the threat to human life and property.

(6) Coal processing waste disposal areas and structures must be designed, constructed, and reclaimed in compliance with ARM 17.24.924 and the requirements of this rule.   In addition, if disposal in valley or head-of-hollow fill is proposed, the relevant requirements of ARM 17.24.925 and 17.24.926 apply.

(7) A properly designed subdrainage system must be installed. Each system must:

(a) freely drain all water discharged beneath the fill;

(b) be protected by an adequate filter;

(c) be covered so as to protect against the entrance of surface water or leachate from the coal processing waste; and

(d) meet the requirements of ARM 17.24.924(13).

(8) (a) During construction or modification of all coal processing waste structures, coal processing waste must be:

(i) spread in layers no more than 24 inches in thickness; and

(ii) compacted to attain 90% of the maximum dry density to prevent spontaneous combustion and to provide the strength required for stability of the coal processing waste.   Dry densities must be determined in accordance with the American Association of State Highway and Transportation Officials (AASHTO) Specifications T99-93 (sixteenth edition, 1993) or an equivalent method.   This publication is on file and available for inspection at the Helena and Billings offices of the department.

(b) Variations may be allowed in the requirements of (a) above for disposal of dewatered fine coal waste (minus 28 sieve size) with approval of the department.

(9) Following grading of the coal processing waste disposal area, the site must be covered with a minimum of 4 feet of the best available non-toxic and non-combustible material, and in a manner that does not impede flow from subdrainage systems.   Toxic, acid-forming and other deleterious coal processing waste must be handled and covered in accordance with ARM 17.24.501(2) and 17.24.505(2).   The coal processing waste disposal area must be revegetated in accordance with subchapter 7.

(10) Coal processing waste fires must be extinguished by the operator in accordance with a plan approved by the department and in compliance with the applicable requirements of the mine safety and health administration. The plan must contain, at a minimum, provisions to ensure that only those persons authorized by the operator and who have an understanding of the procedures to be used may be involved in the extinguishing operations.


History: 82-4-205, 82-4-231, MCA; IMP, 82-4-227, 82-4-231, 82-4-232, 82-4-233, MCA; NEW, 1990 MAR p. 936, Eff. 5/18/90; AMD, 1994 MAR p. 2957, Eff. 11/11/94; TRANS, from DSL, 1996 MAR p. 3042; AMD, 1999 MAR p. 811, Eff. 4/23/99; AMD, 1999 MAR p. 2768, Eff. 12/3/99; AMD, 2004 MAR p. 2548, Eff. 10/22/04; AMD, 2024 MAR p. 258, Eff. 2/10/24.