CFR > Title 30 - Mineral Resources > CHAPTER I—MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR > SUBCHAPTER O—COAL MINE SAFETY AND HEALTH (parts 70 to 90) > PART 75—MANDATORY SAFETY STANDARDS—UNDERGROUND COAL MINES > SUBPART C—Roof Support (§75.200 to §75.223) > 75.207—Pillar recovery.

75.207—Pillar recovery.

Pillar recovery shall be conducted in the following manner, unless otherwise specified in the roof control plan:
(a) Full and partial pillar recovery shall not be conducted on the same pillar line, except where physical conditions such as unstable floor or roof, falls of roof, oil and gas well barriers or surface subsidence require that pillars be left in place.
(b) Before mining is started in a pillar split or lift—
(1) At least two rows of breaker posts or equivalent support shall be installed—
(i) As close to the initial intended breakline as practicable; and
(ii) Across each opening leading into an area where full or partial pillar extraction has been completed.
(2) A row of roadside-radius (turn) posts or equivalent support shall be installed leading into the split or lift.
(c) Before mining is started on a final stump—
(1) At least 2 rows of posts or equivalent support shall be installed on not more than 4-foot centers on each side of the roadway; and
(2) Only one open roadway, which shall not exceed 16 feet wide, shall lead from solid pillars to the final stump of a pillar. Where posts are used as the sole means of roof support, the width of the roadway shall not exceed 14 feet.
(d) During open-end pillar extraction, at least 2 rows of breaker posts or equivalent support shall be installed on not more than 4-foot centers. These supports shall be installed between the lift to be started and the area where pillars have been extracted. These supports shall be maintained to within 7 feet of the face and the width of the roadway shall not exceed 16 feet. Where posts are used as the sole means of roof support, the width of the roadway shall not exceed 14 feet.