(a) A lessee may apply for a modification of a lease to include coal lands or coal deposits contiguous to those embraced in a lease. In no event shall the acreage in the application, when combined with the total area added by all modifications made after August 4, 1976, exceed 160 acres or the number of acres in the original lease, whichever is less.

(b) The lessee shall file the application for modification in the Bureau of Land Management State Office having jurisdiction over the lands involved (43 CFR subpart 1821), describing the additional lands desired, the lessee's needs or reasons for such modification, and the reasons why the modification would be to the advantage of the United States.