The City may change and readjust the aforementioned charges, rates or rentals from time to time, where in the judgment of the City Council special conditions as to the use of water and discharge of sewage into the sanitary sewage facilities exist to the extent that the application of the basic rentals provided for herein would be inequitable and may from time to time fix and readjust such charges, rates, or rentals for a particular classification and for unusual conditions and variations in the character and quantity of sewage and industrial wastes as, in the discretion of the Council, shall be deemed fair and equitable; and, in any event, such charges, rates, or rentals shall be established, adjusted, and maintained so as to be sufficient each year for the payment of the proper and reasonable expense of operation, repair, replacements, and maintenance of said sanitary sewer facilities, for the payment of the requirements of a sinking fund to meet principal and interest and other charges for outstanding revenue bonds issued to pay the cost of construction of said sanitary sewage facilities, and to build up and maintain a requisite depreciation fund. (Ord. 94-93, 5-31-1994)