Any ordinance authorizing the issuance of bonds hereunder, or any trust indenture with any banking institution or trust company, within or without the state, for the security of said bonds, which any municipality is hereby empowered and authorized to enter into and execute, may contain covenants with the holders of the bonds as to:

(a) The purpose or purposes to which the proceeds of sale of bonds or the revenues derived from said combined system may be applied and the securing, use and disposition thereof, including, if considered desirable, the appointment of a trustee or depository for any of the funds;

(b) The pledging of all or any part of the revenues derived from the ownership, control or operation of such combined system, including any part thereof heretofore or hereafter acquired, constructed, established, extended, equipped, added to, bettered or improved or derived from any other sources, to the payment of the principal of or interest thereon of bonds issued hereunder and for reserve or other funds as may be considered necessary or desirable;

(c) The fixing, establishing and collecting of rates, fees or charges for the use of the services and facilities of the combined system, including the parts thereof heretofore or hereafter acquired, constructed, established, extended, equipped, added to, bettered or improved and the revision of same from time to time, as will always provide revenues at least sufficient to provide for all expenses of repair, maintenance and operation of such combined system, the payment of the principal of and interest upon all bonds or other obligations payable from the revenues of such combined system, and all reserve and other funds required by the terms of the ordinance authorizing the issuance of bonds;

(d) The transfer from the General Funds of the municipality to the account or accounts of the combined system of an amount equal to the cost of furnishing the municipality or any of its departments, boards or agencies with the services and facilities of such combined system;

(e) Limitations or restrictions upon the issuance of additional bonds or other obligations payable from the revenues of such combined system, and the rank or priority, as to lien and source and security for payment from the revenues of such combined system, between bonds payable from the revenues;

(f) The manner and terms upon which all bonds and other obligations issued hereunder may be declared immediately due and payable upon the happening of a default in the payment of the principal of or interest thereon, or in the performance of any covenant or agreement with bondholders, and the manner and terms upon which defaults may be declared cured and the acceleration of the maturity of the bonds rescinded and repealed;

(g) Budgets for the annual repair, maintenance and operation of such combined system and restrictions and limitations upon expenditures for the purposes, and the manner of adoption, modification, repeal or amendment thereof, including the approval of the budgets by consulting engineers designated by holders of bonds issued hereunder;

(h) The amounts of insurance to be maintained upon the combined system, or any part thereof, and the use and disposition of the proceeds of any insurance; and

(i) The keeping of books of account, relating to such undertaking and the audit and inspection thereof, and the furnishing to the holders of bonds issued hereunder or their representatives, reports prepared, certified or approved by accountants designated or approved by the holders of bonds issued hereunder.

Any ordinance or trust indenture may also contain other additional covenants as shall be considered necessary or desirable for the security of the holders of bonds issued under the provisions of this article, notwithstanding that other covenants are not expressly enumerated above, it being the intention hereof to grant to municipalities plenary power and authority to make any and all covenants or agreements necessary in order to secure greater marketability for bonds issued hereunder as fully and to the same extent as covenants or agreements could be made by a private corporation rendering similar services and facilities and to grant to municipalities full and complete power and authority to enter into any contracts, covenants or agreements with holders of bonds issued hereunder not inconsistent with the Constitution of this state.