When discharges of abnormal wastewaters are approved by the approving authority, the persons generating such waste shall be excised a monthly surcharge for excess B.O.D. and/or S.S. calculated in accordance with the following formula.
SC = (Q) (8.34) [a (B.O.D. - 250) + b (SS - 250)]
where:
SC = surcharge based on excessive concentrations of B.O.D. and/or S.S. (dollars per month)
Q = flow (million gallons per month)
a = annually adjusted unit cost of treatment, chargeable to B.O.D. (dollars per pound of B.O.D. introduced to system)
b = annually adjusted unit cost of treatment, chargeable to S.S. (dollars per pound of S.S. introduced to system)
The value of B.O.D. and/or S.S. concentrations will be the average of values determined by testing procedures as defined in § 51.027. The value of a and b will be determined by the approving authority based on the current adjusted surcharge rate determined by the Trinity River Authority.
('78 Code, § 17-38) (Ord. 328, passed 6-13-77)