43 CFR § 3809.431 - When must I modify my plan of operations?
You must modify your plan of operations when any of the following apply:
(b) When BLM requires you to do so to prevent unnecessary or undue degradation; and
(c) Before final closure, to address impacts from unanticipated events or conditions or newly discovered circumstances or information, including the following:
(1) Development of acid or toxic drainage;
(2) Loss of surface springs or water supplies;
(3) The need for long-term water treatment and site maintenance;
(4) Repair of reclamation failures;
(5) Plans for assuring the adequacy of containment structures and the integrity of closed waste units;
(6) Providing for post-closure management; and (7) Eliminating hazards to public safety.