In addition to the powers which departments may otherwise have, any department shall have the power pursuant to this part:
(5) To pledge to the punctual payment of the revenue bonds and interest thereon, or to covenant to pay into any special funds from which any of the revenue bonds may be payable, all or any portion of the revenue of the undertaking or loan program or of any part thereof, or the user taxes derived therefrom, or any combination of both (including improvements, betterments, or extensions thereto thereafter constructed or acquired) sufficient, among other things, to pay the revenue bonds and interest as they shall become due and to create and maintain reasonable reserves to pay the principal and interest; provided that no user taxes shall be pledged to the payment unless the legislature in the specific act or acts authorizing the issuance of the revenue bonds shall have provided that the revenue bonds may be payable from and secured by user taxes. The department, in determining the cost, may include all costs and estimated costs of the issuance of the revenue bonds, all architectural, engineering, inspection, financial and legal expenses, all costs of establishing or administering a loan program authorized by law, the cost of causing the payment of the principal or interest or both of the revenue bonds to be insured or guaranteed, the initial cost of any support facility obtained as permitted by section 39-59, and interest which it is estimated will accrue during the construction period and for six months thereafter on money borrowed or which it is estimated will be borrowed pursuant to this part.