When the limits in a categorical pretreatment standard are expressed only in terms of mass of pollutant per unit of production, the Superintendent may convert the limits to equivalent limitations expressed either as mass of pollutant discharged per day or effluent concentration for purposes of calculating effluent limitations applicable to individual industrial users.
(a) When calculating equivalent mass-per-day limitations under this section, the Superintendent shall calculate such limitations by multiplying the limits in the standard by the industrial user's average rate of production. This average rate of production shall be based not upon the designed production capacity, but, rather, upon a reasonable measure of the industrial user's actual long-term daily production, such as the average daily production during a representative year. For new sources, actual production shall be estimated using projected production.
(b) When calculating equivalent concentration limitations under this section, the Superintendent shall calculate such limitations by dividing the mass by the average daily flow rate of the industrial user's regulated process wastewater. This average daily flow rate shall be based upon a reasonable measure of the industrial user's actual long-term average flow rate, such as the average daily flow rate during the representative year.
(c) Equivalent limitations calculated in accordance with this section shall be deemed pretreatment standards for the purposes of Section 307(d) of the Act and this chapter. Industrial users will be required to comply with the equivalent limitations in lieu of the promulgated categorical standards from which the equivalent limitations were derived.
(d) If categorical pretreatment standards specify one limit for calculating maximum daily discharge limitations and a second limit for calculating maximum monthly average, or four-day average limitations, where applied, the same production of flow figure shall be used in calculating both types of equivalent limitations.
(e) Any industrial user operating under a control mechanism incorporating equivalent mass of concentration limits calculated from a production-based standard shall notify the Superintendent within two business days after the user has a reasonable basis to know that the production level will significantly change within the next calendar month. Any user not notifying the Superintendent of such anticipated change will be required to meet the mass or concentration limits in its control mechanism that were used on the original estimate of the long-term average production rate.
(Ord. 97-4. Passed 9-8-97.)