020-5 Wyo. Code R. § 5-6
(a) Unless otherwise determined by the Administrator that the coal reserves make it impracticable to recover the remaining resource, the operator shall leave areas of undisturbed coal as approved by the Administrator to provide access for removal of those reserves by future underground mining.
(b) Auger mining may be limited or prohibited to minimize disturbance of the prevailing hydrologic balance, unwarranted subsidence, or if the prohibition is necessary to maximize the utilization, recoverability or conservation of the solid fuel resources.
(c) Each auger hole shall be capped, sealed, or plugged in accordance with Chapter 14, unless other management techniques are approved by the Administrator. Each auger hole shall be plugged within 72 hours after completion if it is discharging water containing toxic-forming or acid-forming material by backfilling and compacting noncombustible and impervious material into the hole to a depth sufficient to form a watertight seal. Auger holes shall not be sealed with an impervious material if the Administrator determines that the resulting impounded water may create a hazard to the environment or public health or safety. Auger holes that are not discharging water, or if the discharging water does not contain toxic-forming or acid-forming material and will not pose a threat of pollution to groundwater as required by Chapter 4, Section 2(c) (xiii), shall be backfilled as contemporaneously as practicable and will not require sealing with an impervious material.
(d) Subsidence control shall be provided as required by Chapter 7, Section 2.
(e) Where auger mining operations are conducted in previously mined areas that were not reclaimed to the standards of Chapter 4, Section 2(b), the reaffected lands shall be reclaimed in accordance with the requirements of Section 7 of this Chapter. Any coal seam mined shall be covered with a minimum of four feet of nonacid and nontoxic-forming material and graded to a slope which is stable, compatible with the approved postmining land use, and provides drainage. The operator shall provide the Administrator a written demonstration, prepared by a qualified registered professional engineer, showing the fill has a minimum static safety factor of 1.3.
020-5 Wyo. Code R. § 5-6