1. For any user, when the BOD exceeds *250 mg/1, the suspended solids exceeds *250 mg/1, or when other pollutant concentrations exceed the range of concentrations of these pollutants in normal domestic sewage, a surcharge shall be added to the basic charge. This surcharge shall be calculated by the following formula. (*Maximum limit for average domestic waste.)
Cs = (Bc (B) + Sc (S) + Pc (P)VU
2. Symbols and definitions shall be as follows:
Cs = A surcharge for wastewaters of excessive strength;
Bc = O&M cost for treatment of a unit of biochemical oxygen demand (BOD);
B = Concentration of BOD from a user above a base level;
Sc = O&M cost for treatment of a unit of suspended solids (SS);
S = Concentration of SS from a user above a base level;
Pc = O&M cost for treatment of a unit of any pollutant;
P = Concentration of any pollutant from a user above a base level; and
Vu = Volume contribution from a user per unit of time.