(A) The sewer service charges established in this chapter shall not prevent the assessment of additional charges, or surcharges, to users who discharge wastes with concentrations greater than normal domestic strength or wastes of unusual character, or contractual agreements with these users, as long as the following conditions are met:
(1) The user pays operation, maintenance and replacement costs in proportion to the user’s proportionate contribution of wastewater flows and loadings to the treatment plant, and no user is charged at a rate less than that of normal domestic strength wastewater.
(2) The measurements of these wastes are conducted according to the latest edition of Standard Methods for the Examination of Water and Wastewater in a manner acceptable to the city as provided for in § 53.057.
(B) Surcharges shall be computed in the following manner:
SCi = (ICi - NCi) x Q x 8.34 x CPi
(C) For the formula above:
(1) SCi = surcharge for BOD, TSS, or other constituent as determined by the city;
(2) ICi = average concentration of BOD, TSS, or other constituent, in the user’s wastewater discharge;
(3) NCi = normal domestic strength concentration of BOD, TSS, or other constituent;
(4) Q = billable wastewater volume, in million gallons;
(5) CPi = charge per pound of BOD, TSS or other constituent; and
(6) The value of CPi is determined by dividing the yearly estimated operation, maintenance, and replacement costs attributable to BOD, TSS, or other significant waste constituent as determined by the city, by the total annual load of that constituent to the wastewater treatment facilities, in pounds.
(Ord. 303, passed 4-21-88)