Code of Federal Regulations Title 43. Public Lands:  Interior § 43.3432.2 Availability

(a) The authorized officer may modify the lease to include all or part of the lands applied for if he determines that:  (1) The modification serves the interests of the United States;  (2) there is no competitive interest in the lands or deposits;  and (3) the additional lands or deposits cannot be developed as part of another potential or existing independent operation.

(b) Coal deposits underlying land the surface of which is held by a qualified surface owner, and which would be mined by other than underground mining techniques, may not be added to a lease by modification.

(c) The lands applied for shall be added to the existing lease without competitive bidding, but the United States shall receive the fair market value of the lease of the added lands, either by cash payment or adjustment of the royalty applicable to the lands added to the lease by the modification.