(a) Definition. Special bituminous coal surface mines as used in this section means those bituminous coal surface mines that are located in the State of Wyoming and that are being mined or will be mined according to the following criteria:

(1) Excavation of the mine pit takes place on a relatively limited site for an extended period of time. For the purposes of this section, mine pit means an open-pit mine in which the surface opening is at least the full size of the excavation and has a contiguous border. The pit generally is quite deep and is formed by the removal of relatively large amounts of overburden to obtain lesser amounts of coal. The term as used in this section applies only to mining operations that extract coal from seams dipping 15 degrees or more from the horizontal.

(2) Excavation of the mine pit follows a coal seam that inclines 15 degrees or more from the horizontal, and as the excavation proceeds downward it expands laterally to maintain stability of the pitwall or as necessary to accommodate the orderly expansion of the total mining operations.

(3)

(i) Surface coal mining operations in the mine pit have taken place since January 1, 1972, and

(A) Operations in the mine pit are removing more than one coal seam, and

(B) Mining has begun on the deepest coal seam scheduled to be mined; or

(ii) Surface coal mining operations which may be developed after August 3, 1977, and are conducted on lands immediately adjacent to operations meeting the criteria of paragraph (a)(3)(i) of this section.

(4) The amount of material removed from the pit is large in proportion to the surface area disturbed.

(5) There is no practicable alternative to the deep open-pit method of mining the coal.

(6) There is no practicable way to entirely reclaim the land as required by part 715 of this chapter.

(b) Requirements for special bituminous coal mines operating prior to July 1, 1973. Those portions of a special bituminous coal mine approved for operation prior to July 1, 1973, including the orderly expansion of such a mine pit to the extent authorized by State law, shall at a minimum meet the general performance standards of part 715 of this chapter for all operations conducted on the permit area outside the mine pit and for those operations associated with spoil storage areas. The standards of part 715 also apply to the mine pit with the exception of §715.14, which relates to backfilling and grading. Special requirements for backfilling and grading the mine pit area are as follows:

(1) In the final mine area, highwalls will be allowed to remain and benches will be allowed. Details of the benches shall be included in the mine plans submitted to the regulatory authority for approval.

(2) The exposed pit floors will be sloped and graded to provide access to the area, and topsoil shall be applied and the floor area seeded according to the requirements of §§715.16 and 715.20. Where water impoundments are included as part of the mine plan, riprap may be used if necessary to prevent erosion.

(3) Spoil piles will be graded and contoured with no more than overall slope of 17 degrees allowed, and terraces may be used to break the slope when it can be shown that terraces will accomplish the required reclamation. For the postmining land use, steeper slopes may be permitted upon approval of the regulatory authority, provided it can be demonstrated that such method will provide the required results.

(c) Requirements for other special bituminous coal mines. Those portions of a special bituminous coal mine which do not meet the criteria of paragraph (b) of this section shall, at minimum meet the general performance standards of part 715 of this chapter for all operations conducted on the permit area outside the mine pit and for these operations associated with spoil storage areas. The standards of part 715 also apply to the mine pit with the exception of §715.14, which relates to backfilling and grading. Special requirements for backfilling and grading the mine pit area are as follows:

(1) Slope specifications. Slope specifications for the postmining land use shall be based on an average of the natural slopes measured in the immediate area of the mine site, and the maximum inclination of the slopes in the reclaimed area shall not be greater than this average slope. However, slopes steeper than the average of the natural slopes may be approved by the regulatory authority if it can be demonstrated that returning the minded area to a slope equal to or less than the average natural slope would greatly increase the amount of disturbed land. Measurements of individual slopes, locations at which measurements are made, and the average natural slope as determined from the individual slope measurements shall be submitted for approval to the regulatory authority. The regulatory authority may make an independent slope survey to verify the average natural slope.

(2) Postmining land uses that do not include permanent water impoundments.

(i) The final mine area shall be backfilled, graded, and contoured to the extent necessary to return the land to the use approved by the regulatory authority.

(ii) All backfilling, grading, and contouring shall be done in a manner to preserve the original drainage system or to provide substitute drainage systems approved by the regulatory authority.

(iii) Terraces or benches may be used only if it can be demonstrated that contouring methods will not provide the required results. Detailed plans of dimensions and design of the terraces or benches, check dams, erosion prevention techniques, and slopes of the terraces or benches and their intervals shall be submitted to the regulatory authority for approval before construction.

(iv) Depressions that will accumulate water shall not be allowed unless they are approved under paragraph (3).

(3) Postmining land uses that include permanent water impoundments.

(i) The exposed mine pit area shall be sloped, graded, and contoured to blend with the topography of the surrounding terrain and to provide for access to the area. Where necessary to prevent erosion, riprap shall be used.

(ii) Under certain conditions where it can be demonstrated by the permittee that the pitwall can be stabilized by terracing or other techniques it may be permissible to leave one-half the proposed shoreline, as measured along the circumference, composed of the stabilized pitwall. The remaining part of the shoreline shall be graded and contoured to blend with the topography of the surrounding terrain and to provide access to the area. Detailed explanations of the techniques to be used to stabilize the pitwalls shall be submitted for approval to the regulatory authority. The regulatory authority may verify the effectiveness of the proposed stabilization techniques from a study made by an independent engineering company and based on this information and an onsite inspection, the regulatory authority will then determine the acceptability of the proposed stabilization techniques.

(d) In the event of an amendment or revision to the State of Wyoming's regulatory program, regulations, or decisions made thereunder governing special bituminous coal mines, the Secretary shall issue such additional regulations as necessary to meet the purposes of the Act.