(a) Each user (or user class) of the public sewer system shall pay its proportionate share of the cost of operation and maintenance (including replacement) of the system based on the user's proportionate contribution to the total waste water loading from all users (or user classes); said public sewer system user fees to be charged pursuant to rules and regulations issued by the Waste Management Authority and subject to public hearings and prior approval by the Public Services Commission.
(b) The family unit (3.5 persons) annual user fee, based upon the 1000 gallon treatment cost as of October 1, 1980, shall be $43.20. Other user classes shall be calculated from that base. The Waste Management Authority shall review waste water treatment costs biennially and may revise user fee regulations appropriately, as provided by the law, based upon results of such review.