30 CFR § 816.101 - Backfilling and grading: Time and distance requirements.
(1) Contour mining. Within 60 days or 1,500 linear feet following coal removal;
(3) Other surface mining methods. In accordance with the schedule established by the regulatory authority. For States with approved State programs, schedules are subject to the State program approval process.
(b) The regulatory authority may extend the time allowed for rough backfilling and grading for the entire permit area or for a specified portion of the permit area if the permittee demonstrates in accordance with § 780.18(b)(3) of this chapter that additional time is necessary.