Moneys derived from rentals, operation, or disposition of property acquired or constructed under the provisions of this subchapter shall be available for expenses of operation, maintenance, improvement, and disposition of any such property, including the establishment of necessary reserves therefor and administrative expenses in connection therewith: Provided, That such moneys derived from rentals, operation, or disposition may be deposited in a common fund account or accounts in the Treasury: And provided further, That the moneys in such common fund account or accounts shall not exceed $5,000,000 at any time, and all moneys in excess of such amount shall be covered into miscellaneous receipts.