52 Pa. Stat. § 681.18
In the event that an operator or owner desires to conduct deep mining upon the premises affected by strip mining, the said operator or owner may make this fact known to the secretary with the request that the backfilling of pits and the planting, as may be necessary to permit deep mining, be deferred during the period of such deep mining. In such case the secretary may defer the backfilling and planting. The deep mining shall be started within six (6) months after the recovery of coal by strip mining is completed. If such request is made by the owner, he shall secure by bond the backfilling of such pit and the planting after the deep mining operation has been completed; if the request is made by the operator, the bond filed under section 6 of this act shall stand as security for such backfilling and planting.
52 P.S. § 681.18