In carrying out his functions, the Secretary, under such terms, at such rates, and for such periods not exceeding five years, as he may deem to be in the public interest, is authorized to permit the use by public and private agencies, corporations, associations, or other organizations or by individuals of any real property, or any facility, structure, or other improvement thereon, under the custody of the Secretary for Department purposes. The Secretary may require permittees under this section to recondition and maintain, at their own expense, the real property, facilities, structures, and improvements involved to a satisfactory standard. This section shall not apply to excess property as defined in section
102
(3) of title
40.