Authority: IC 14-34-2-1

Affected: IC 14-34

Sec. 43. (a) A new or existing impounding structure constructed of coal mine waste or intended to impound coal mine waste must comply with sections 34, 36, and 37 of this rule, this section, and sections 44 through 45 of this rule.

(b) Coal mine waste shall not be used for the construction of an impounding structure unless the permittee demonstrates to the director that the stability of the structure achieves each of the following:

1. (1) Is in conformance with this rule.
2. (2) The use of coal mine waste will not have a detrimental effect on downstream water quality or the environment due to acid seepage through the impounding structure. The stability of the impounding structure and the potential impact of acid mine seepage through the structure must be discussed in detail in the design plan submitted in the reclamation plan under 312 IAC 25-4-49.

(c) An impounding structure constructed of coal mine waste or intended to impound coal mine waste must be designed, constructed, and maintained under section 20 of this rule. The impounding structure cannot be retained permanently as part of the approved postmining land use.

(d) Each impounding structure constructed of coal mine waste or intended to impound coal mine waste that meets the criteria of 30 CFR 77.216(a) shall have:

1. (1) sufficient spillway capacity to safely pass;
2. (2) adequate storage capacity to safely contain; or
3. (3) a combination of storage capacity and spillway capacity to safely control;

the probable maximum precipitation of a six (6) hour precipitation event or greater event as specified by the director. Spillways and outlet works shall be designed to provide adequate protection against erosion and corrosion. Inlets shall be protected against blockage.

(e) Run-off from areas above the disposal facility or run-off from the surface of the facility that may cause instability or erosion of the impounding structure shall be diverted into stabilized diversion channels designed to satisfy section 15 of this rule and to safely pass run-off from the one hundred (100) year, six (6) hour design precipitation event.

(f) As used in this section, "impounding structure" does not include incised impoundments or impoundments plugged by massive earthen fills, as determined by the Mine Safety and Health Administration, that would be treated as incised impoundments under good engineering practices.

(g) For an impounding structure constructed of coal mine waste or impounding coal mine waste, at least ninety percent (90%) of the water stored during the design precipitation event shall be removed within the ten (10) day period following the design precipitation event.

(Natural Resources Commission; 312 IAC 25-6-43; filed Jun 21, 2001, 2:53 p.m.: 24 IR 3531, 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)