43 CFR §3809.331

1. (a)You must modify your notice—
   1. (1)If BLM requires you to do so to prevent unnecessary or undue degradation; or
   2. (2)If you plan to make material changes to your operations. Material changes are changes that disturb areas not described in the existing notice; change your reclamation plan; or result in impacts of a different kind, degree, or extent than those described in the existing notice.
2. (b)You must submit your notice modification 15 calendar days before making any material changes. If BLM determines your notice modification is complete before the 15-day period has elapsed, BLM may notify you to proceed. When BLM requires you to modify your notice, we may also notify you to proceed before the 15-day period has elapsed to prevent unnecessary or undue degradation.