Material damage, in the context of 784.20 and 817.121 of this chapter, means:
(a) Any functional impairment of surface lands, features, structures or facilities;
(b) Any physical change that has a significant adverse impact on the affected land's capability to support any current or reasonably foreseeable uses or causes significant loss in production or income; or
(c) Any significant change in the condition, appearance or utility of any structure or facility from its pre-subsidence condition.
30 CFR § 701.5
As used in this chapter, the following terms have the specified meanings, except where otherwise indicated: