Authority: IC 14-34-2-1

Affected: IC 14-34

Sec. 108. (a) The design of each dam and embankment constructed of coal mine waste shall comply with the applicable requirements of sections 84 and 99 of this rule, modified as follows:

1. (1) The design freeboard between the lowest point on the embankment crest and the maximum water elevation shall be at least three (3) feet.
2. (2) The dam and embankment shall have a minimum safety factor of one and five-tenths (1.5) for the partial pool with steady seepage saturation conditions, and the seismic safety factor shall be at least one and two-tenths (1.2).
3. (3) The dam or embankment foundation and abutments shall be designed to be stable under all conditions of construction and operation of the impoundment. Sufficient foundation investigations and laboratory testing shall be performed to determine the safety factors of the dam or embankment for all loading conditions appearing in subdivision (2).

(b) Spillways and outlet works shall be designed to provide adequate protection against erosion and corrosion. Inlets shall be protected against blockage.

(c) Impounding structures constructed of or impounding coal mine waste shall be designed so that at least ninety percent (90%) of the water stored during the design precipitation event can be removed within a ten (10) day period.

(Natural Resources Commission; 312 IAC 25-6-108; filed Jun 21, 2001, 2:53 p.m.: 24 IR 3568, 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)