30 C.F.R. § 816.100
You must reclaim all land disturbed by surface mining activities as contemporaneously as practicable with the mining operations, except when the mining operations are conducted in accordance with a variance for concurrent surface and underground mining activities under § 785.18 of this chapter. Reclamation activities include, but are not limited to, backfilling, grading, soil replacement, revegetation, and stream restoration.