Pennsylvania Statutes Title 52 P.S. Mines and Mining § 690-703. Pillar recovery

Pillar recovery may not be undertaken until the pillar plan is approved by the department. Applications for pillar recovery must be accompanied by four copies of a plan, which must include such information as shall be determined by the department. The approval or disapproval of the plan shall be based on the factors of depth, the thickness of the bed, the percentage of pillars proposed to be extracted and to be left, the effect on pillars remaining in overlying beds and any other special features deemed necessary by the department.