(a) The ordinance providing for the issuance of the revenue bonds shall set forth a brief description of the contemplated undertaking and must include:
(1) The estimated cost thereof;
(2) The amount of the issue;
(3) The rate of interest;
(4) The time and place of payment; and
(5) Other details in connection with the issuance of the bonds.
(b) The ordinance shall declare that a statutory mortgage lien shall exist upon the property to be constructed, fix the minimum rate to be collected for gas prior to the payment of the bonds, and it shall pledge the revenues derived from the system for the purpose of paying the principal and interest on the bonds.
(c) The pledge shall fix the amount of revenue to be set apart and applied to the payment of the principal and interest on the bonds and the proportion of the balance of such revenues and income to be set aside as an adequate depreciation account and the remainder to be set aside for reasonable and proper operation.