(a) Normal concentrations. All persons discharging industrial waste into the public sewers shall be subjected to a surcharge, in addition to any other sewer-service charges, if these wastes have a concentration greater than the following normal concentrations:
(1) A five-day, 20°C biochemical oxygen demand (BOD) concentration of 250 parts per 1,000,000;
(2) A suspended solids concentration of 300 parts per 1,000,000;
(3) A phosphorous (measured as P) concentration of 20 parts per 1,000,000;
(4) An ammonia (measured as N) concentration of 15 parts per 1,000,000; or
(5) An oil and grease (hexane extractable or suitable alternative solvent) concentration of 100 parts per 1,000,000.
(Ord. 1998-21, passed 2-2-1998; Ord. 2002-32, passed 2-4-2002; Ord. 2010-89, passed 4-19-2010)
(b) Items contained in surcharge. The amount of surcharge shall reflect the cost incurred by the city in removing the excess biochemical oxygen demand (BOD), suspended solids, phosphates, ammonia, and oil and grease of the waste load. This surcharge may include a proportionate share of the following:
(1) Fixed charges and amortization costs for the sewage disposal works based upon an average useful life of 25 years and an annual interest rate of 5% and under the assumption that the capital investment will be retired at a uniform rate throughout the life of the facilities. Such basis of fixed charges shall be recalculated each five years or at the end of major construction periods, whichever is shorter; and
(2) The annual cost of operation of the sewage treatment plants, including repairs and maintenance and the cost of administering this chapter.
(Ord. 1991-239, passed 12-2-1991)