In determining the amount of the surcharges to be imposed upon issuance of the permit to allow discharge of excessive flows of characteristic industrial wastes, the following principles shall apply:
(1) It shall be the policy of the city that the additional costs incurred by virtue or the receipt and treatment of such industrial waste shall be paid by the dischargers. The surcharge shall be based upon the amount of such discharge as shall be in excess of the normal, it being intended that the basic sewer service charges established pursuant to section 5-1-87 shall represent payment for the normal.
(2) The surcharge shall take into consideration the fixed charges and amortization costs of such additional plant capacity as may be required, as well as an increase in operating costs. (Ord. of 4/5/77, Div. V, Art. 2)