(a) (1) All persons discharging industrial wastes 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:
A. A five-day twenty degrees centigrade BOD of 200 parts per million, or
B. A suspended solids content of 250 parts per million.
(2) The amount of surcharge shall reflect the cost incurred by the City in removing the excess BOD and SS, and the surcharge shall include a proportionate share of the following:
A. Fixed charges and amortization costs for the sewage disposal works based on the useful life of thirty years and annual interest rate 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 annually, or at the end of a major construction period, whichever is shorter; and
B. The annual cost of operation of the sewage treatment plant, including repairs, maintenance and replacement.
(b) The surcharge per person shall be determined as follows:
The excess pounds of BOD and SS will be computed by multiplying the person's sewage flow volume in million gallons per day by the constant 8.345 and then multiplying this product by the difference between the person's concentration of BOD and SS and the aforementioned normal concentrations in parts per million by weight. The surcharge for each constituent will then be determined by multiplying the excess pounds of each constituent by the appropriate rate of surcharge listed, below. This product will then be multiplied by the number of days in the billing period to determine the surcharge. Concentrations in these calculations shall be daily averages.
(c) The rates of surcharge for each of the aforementioned constituents shall be as follows:
(1) For biochemical oxygen demand, .16/lb. over allowable;
(2) For suspended solids, .17/lb. over allowable.
(d) The rates of surcharge shall be reviewed annually by the approving authority in order to determine whether or not they are sufficient to defray the fixed charges, amortization costs and annual cost of operation and maintenance (including replacement) as determined from the wastewater treatment facility records. If the difference between the revenue derived from the rates of surcharge and the total amount cost is sufficient to justify an increase or decrease in the rates, the approving authority shall make such recommendation as is appropriate to Council. (Ord. 1979-11. Passed 1-30- 79.)