(a) 
Often, the wastewater discharged from businesses contains solids and organic matter at higher concentrations in comparison to concentrations found in residential wastewater. Wastewater is considered to be “normal strength” if it meets the wastewater quality standards established for typical residential wastewater (see “normal values” in the table below). Wastewater that exceeds these standards is considered to be “extra strength.” Much of the cost associated with treating wastewater is related to the amount of solids that must be removed and the amount of oxygen that is required to stabilize and digest that organic matter in the wastewater. As such, the treatment of wastewater from some businesses is significantly more expensive than the treatment of typical residential wastewater.
(b) 
Relying on the periodic collection and analyses of wastewater samples from each permitted source of industrial waste, the surcharge program enables the city to recover the extra costs associated with the treatment of extra strength wastewater. Designated individualized surcharges are determined for each industrial source. These surcharges are based on site-specific sample results for biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total suspended solids (TSS).
(c) 
Normal values:
(1) 
BOD less than 250 mg/l;
(2) 
TSS less than 250 mg/l;
(3) 
O&G less than 50 mg/l;
(4) 
COD less than 560 mg/l; and
(5) 
pH 5.5 to 10.0 mg/l.
(d) 
All users subject to a surcharge are notified by letter, and the monthly surcharge fees are applied to the user’s monthly utility bill.
(Ordinance 395, sec. 2, adopted 7/21/15)
(a) 
For industrial wastes having a COD concentration of 2.25 or more times that of the BOD concentration, the surcharge will be based on Formula 2 below. Computations of surcharges shall be based on the following formulas:
Formula 1
S = [(BOD - 250) + (TSS - 250) + (4 x O&G - 200)] x 0.001
Formula 2
S = [(0.44 x COD - 250) + (TSS - 250) + (4 x O&G - 200)] x 0.001
Where:
S = Surcharge factor applied to wastewater charge.
(b) 
The surcharge is computed by multiplying the monthly wastewater charge for the facility by S.
(c) 
BOD, TSS, O&G, and COD refer to the annual average concentrations of those parameters measured in mg/l as reported by the permit holder or as measured by the city manager. If the concentration of any of these pollutants is less than the concentration of normal wastewater, then the term in the equation for that parameter will be deleted.
(d) 
(1) 
All flow rates, BOD, COD, O&G and TSS values used in determination of the surcharge of major wastewater customers shall be reevaluated on an annual basis and shall be adjusted to reflect any increase or decrease in wastewater treatment costs based on the previous year’s experience. However, if there is a major change in the operation to cause changes in value, the values may be increased or decreased during the calendar year based on a study of changes or actual measurements.
(2) 
The permit holder may request an adjustment of surcharge after submittal of any self-monitoring report.
(Ordinance 395, sec. 2, adopted 7/21/15)