(a) Rates shall be determined by an annual audit of sewage utility operation and maintenance expenditures incurred in the transportation of sewage and removal process of B.O.D. and S.S.

(b) The unit charges shall be applied to the following formula to determine the appropriate surcharge to be leveled against each person exceeding the limits set out in 50.25.

S = Vs (8.34)[A(B.O.D. - 200) + B(S.S. - 225)]
S = Surcharge in dollars
Vs = Sewage volume in million gallons
8.34 = Pounds per million gallons of water
A* = Unit charge for B.O.D. in dollars per pound
B.O.D. = Biochemical oxygen demand, strength index in milligrams per liter
200 = Allowed B.O.D. strength in milligrams per liter
B* = Unit charge for suspended solids in dollars per pound
S.S. = Suspended solids strength index in milligrams per liter
225 = Allowed S.S. strength in milligrams per liter

*To be determined by annual audit of sewage utility operation and maintenance expenditures inucrred in the transportation of sewage and removal process of B.O.D. and S.S. (Ord. 2858-1973) Penalty, see 10.99