25 Pa. Code § 77.571 – Bench development.

The height of the working face on a bench shall be limited as follows:

(1) The maximum height of the working face of a bench in consolidated material—other than thin seam operation which will be returned to AOC—may not exceed 50 feet except as follows:
1. (i) If topography influences the height of the uppermost face, the highwall may be developed to 65 feet.
2. (ii) If geologic or safety considerations require the development of a lower working face height.
(2) The Department may grant a waiver to develop a greater height on the working face if a stability analysis shows the proposed face to be stable and the applicant demonstrates with clear and convincing evidence that there is no practical alternative to developing a greater height. The stability analysis shall be performed under § 77.573 (relating to stability analysis).
(3) The maximum height of the working face of a bench in unconsolidated material shall be 25 feet. The Department may grant a waiver to develop a greater height to the working face based on the type of equipment to be used and a field assessment by the Department on the stability of the face.
(4) The minimum width for a horizontal bench between successive working faces shall be 25 feet.
(5) The Department may impose lower working face heights on the working face if the working face is a potential threat to health or safety.

The provisions of this § 77.571 adopted March 16, 1990, effective March 17, 1990, 20 Pa.B. 1643.

This section cited in 25 Pa. Code § 77.573 (relating to stability analysis).