312 IAC 25-6-34 Surface mining; disposal of excess spoil

Sec. 34. (a) All excess spoil material resulting from mining and reclamation activities must be placed as follows: (1) Spoil shall be transported and placed in a controlled manner in a position for concurrent compaction, and to: (A) assure stability; (B) prevent mass movement; and (C) ensure a long term static safety factor of one and five-tenths (1.5). (2) The areas of disposal shall be within the bonded permit areas, and all organic matter shall be removed immediately before spoil placement. (3) Sufficient surface and internal drainage systems and diversion ditches shall be used to prevent spoil erosion and movement. (4) The disposal area shall not contain springs, natural water courses, or wet weather seeps unless lateral drains are constructed from the wet areas to the main underdrains to prevent the infiltration of the water into the spoil pile. (5) If placed on a slope, the spoil shall be placed upon the most moderate slope available that the director determines will ensure compliance with IC 14-34. If possible, the spoil shall be placed upon or above a natural terrace, bench, or berm if this placement will provide additional stability and prevent mass movement. (6) Where the toe of the spoil rests on a downslope, a rock toe buttress of sufficient size to prevent mass movement shall be constructed. (7) The final configuration shall be compatible with the natural drainage pattern and surroundings and suitable for intended uses. Terraces may be constructed on the outslope if required for stability, control of erosion, conservation of soil moisture, or facilitation of the approved postmining land use. The grade of the outslope between terrace benches shall not be steeper than fifty percent (50%), 2h:1v. (8) The spoil disposal area shall be designed and inspected during construction under the supervision of, and certified after construction by, a qualified registered professional engineer. (9) The foundation and abutments of the fill shall be stable under all conditions of construction and operation. Sufficient foundation investigation and laboratory testing of foundation materials shall be performed to determine the design requirements for stability of the foundation. Analyses of foundation conditions shall include the effect of underground mine workings upon the stability of the structure. (10) Spoil shall be placed in horizontal lifts not exceeding four (4) feet thick, except where the director approves a greater thickness based upon: (A) a certification by a qualified registered professional engineer that the design ensures the stability of the fill; and (B) a demonstration by the permittee that all other requirements of this section are satisfied. (11) No permanent impoundments shall be allowed on the completed fill. Small depressions may be allowed by the director if they are needed to retain moisture, minimize erosion, create and enhance wildlife habitat, or assist revegetation, and if they are not incompatible with stability of the fill. (b) All box cut spoil that is demonstrated to be excess spoil under section 50 of this rule must conform to the following: (1) Topsoil shall be removed from the area upon which the box cut spoil will be placed. (2) The topsoil shall be handled consistently with the topsoil storage and replacement requirements of this article. (3) If placed on a slope, the box cut spoil shall be placed upon the most moderate slope available which the director determines will ensure compliance with IC 14-34 and which will prevent mass movement. (4) The final graded slope of box cut spoil areas shall not exceed thirty-three and one-third percent (33 %) or any lesser slope approved by the director based upon a consideration of soil, climate, land use, or other characteristics of the surrounding area. (5) The final surface configuration shall be compatible with the natural drainage pattern and surroundings, and the reclamation of the box cut spoil shall achieve an ecologically sound land use compatible with existing land use policies and plans. (c) Excess spoil areas, including box cut spoil approved as excess as outlined under subsection (b), shall be inspected by a qualified registered professional engineer or another qualified specialist under the direction of a qualified registered professional engineer, who shall periodically inspect the fill during construction. The professional engineer or specialist must be experienced in the construction of earth and rock fills. (d) The inspections required under subsection (c) must be made at least quarterly throughout construction and during critical construction periods. Critical construction periods include the following: (1) Foundation preparation including the removal of organic material and topsoil. (2) The placement of underdrains and protective filter systems. (3) The installation of final surface drainage systems. (4) The placement and compaction of fill materials. (5) The establishment of final graded and revegetated fill. (e) The registered professional engineer shall provide a report to the director promptly after each inspection performed under subsection (c) that certifies that any fill has been constructed and maintained as designed and under the approved reclamation plan and this article. The report shall identify any appearance of instability, structural weakness, or other hazardous condition. A report on any drainage system or protective filter shall include color photographs taken during and after construction (but before an underdrain is covered with excess spoil). If an underdrain system is constructed in phases, each phase shall be certified separately. (f) A copy of each inspection report shall be retained at or near the mine site.