98.01   BASIS FOR CHARGES.
The wastewater service charge for the use of and for service supplied by the wastewater facilities of the City shall consist of a basic user charge for operation and maintenance plus replacement and local capital financing charge and a surcharge, if applicable. The user charge shall be based on water usage as recorded by water meters and/or sewage meters for wastes having the following normal domestic wastewater concentrations:
1.   Average day, 20 degrees centigrade (20ºC) biochemical oxygen demand (BOD) of 200 mg/l.
2.   A suspended solids (SS) content of 240 mg/l.
3.   An ammonia-nitrogen (NH3N) content of 40 mg/l.
4.   An oil and grease content of 100 mg/l.
5.   A sulfate content of 1,500 mg/l.
It shall consist of operation and maintenance costs plus replacement and shall be computed as follows:
1.   Estimate wastewater characteristics by volume, pounds of SS, pounds of BOD, pounds of NH3N and pounds of oil and grease to be treated, and customer bills to be sent.
2.   Estimate the projected annual revenue required to operate and maintain the wastewater facilities including a replacement fund for the year, for all works categories.
3.   Proportion the estimated costs to wastewater facility categories by volume, SS, BOD, ammonia-nitrogen (NH3N), oil and grease, and customer.
4.   Develop unit rates for volume, BOD, SS, and NH3N, and oil and grease by dividing estimated costs in the preceding paragraph 3 by estimated wastewater characteristics in paragraph 1.
5.   Compute costs per 1000 gallons for normal domestic wastewater.
6.   Compute surcharge factor for multiplying time costs per 1000 gallons for BOD, SS, NH3N, and oil and grease in excess of normal domestic wastewater. A surcharge will also be assessed for heavy metals or toxics that exceed acceptable limits. The charge will be determined according to the toxic or heavy metals involved.