Authority: IC 14-34-2-1

Affected: IC 14-34

Sec. 144. (a) Surface mining activities or underground mining activities on steep slopes shall be conducted so as to meet the requirements of 312 IAC 25-6-50 and 312 IAC 25-6-112, and the requirements of this rule except where mining is conducted on flat or gently rolling terrain with an occasional steep slope through which the mining proceeds and leaves a plain or predominately flat area.

(b) The following materials shall not be placed on the downslope:

1. (1) Spoil.
2. (2) Waste materials of any type.
3. (3) Debris, including that from clearing and grubbing.
4. (4) Abandoned or disabled equipment.

(c) Land above the highwall shall not be disturbed unless the director finds that this disturbance will facilitate compliance with the environmental protection standards of this rule and the disturbance is limited to that necessary to facilitate compliance.

(d) Woody material shall not be buried in the backfilled area unless the director determines that the proposed method for placing woody material within the backfill will not deteriorate the stable condition of the backfill area.

(e) The disturbed area shall be backfilled and graded to comply with the provisions of sections 50 and 112 of this rule to return the site to approximate original contour and completely cover the highwall; provided, however, that where mining operations affect previously mined areas that were not reclaimed to the standards of sections 50 and 112 of this rule and the volume of all reasonably available spoil is demonstrated in writing to the director in the approved permit application to be insufficient to completely backfill the highwall, the highwall shall be eliminated to the maximum extent technically practical in accordance with the following criteria:

1. (1) The permittee shall demonstrate to the director in the approved permit application or to the director that the fill, designed by a qualified registered professional engineer, has a minimum static safety factor for the stability of the backfill of at least one and three-tenths (1.3).
2. (2) All spoil generated by the mining operation and other reasonably available spoil shall be used to backfill the area. Reasonably available spoil shall include spoil generated by the mining operation and other spoil located in the permit area that is accessible and available for use and that when rehandled will not cause a hazard to the public safety or significant damage to the environment.

3. (3) The backfill shall be graded to a slope that:

   1. (A) is compatible with the approved postmining land use; and
   2. (B) provides adequate drainage and long term stability.
4. (4) Any remnant of the highwall shall be stable and not pose a hazard to the public health and safety or to the environment.
5. (5) Spoil placed on the outslope during previous mining operations shall not be disturbed if such disturbances will cause instability of the remaining spoil or otherwise increase the hazard to the public health and safety or to the environment.

(Natural Resources Commission; 312 IAC 25-6-144; filed Jun 21, 2001, 2:53 p.m.: 24 IR 3587, eff Dec 1, 2001; readopted filed May 29, 2007, 9:51 a.m.: 20070613-IR-312070146RFA; readopted filed Sep 19, 2013, 10:12 a.m.: 20131016-IR-312130125RFA; readopted filed Mar 26, 2019, 3:40 p.m.: 20190424-IR-312190011RFA; readopted filed Mar 25, 2025, 9:50 a.m.: 20250423-IR-312240574RFA)