The national categorical pretreatment standards found at 40 C.F.R. Ch. I, Subch. N, parts 405–471, as amended, are hereby incorporated.
(A) Where a categorical pretreatment standard is expressed only in terms of either the mass or the concentration of a pollutant in wastewater, the General Manager may impose equivalent concentration or mass limits in accordance with division (C) of this section.
(B) When the limits in a categorical pretreatment standard are expressed only in terms of mass of pollutant per unit of production, the General Manager 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.
(C) When the limits in a categorical pretreatment standard are expressed only in terms of pollutant concentrations, an industrial user may request that the General Manager convert the limits to equivalent mass limits. The determination to convert concentration limits to mass limits is within the discretion of the General Manager. The General Manager may establish equivalent mass limits only if the industrial user meets all the following conditions in divisions (C)(1)(a) through (C)(1)(e) of this section.
(1) To be eligible for equivalent mass limits, the industrial user must:
(a) Employ, or demonstrate that it will employ, water conservation methods and technologies that substantially reduce water use during the term of its individual wastewater discharge permit;
(b) Currently use control and treatment technologies adequate to achieve compliance with the applicable categorical pretreatment standard, and not have used dilution as a substitute for treatment;
(c) Provide sufficient information to establish the facility’s actual average daily flow rate for all wastestreams, based on data from a continuous effluent flow monitoring device, as well as the facility’s long-term average production rate. Both the actual average daily flow rate and the long-term average production rate must be representative of current operating conditions;
(d) Not have daily flow rates, production levels, or pollutant levels that vary so significantly that equivalent mass limits are not appropriate to control the discharge; and
(e) Have consistently complied with all applicable categorical pretreatment standards during the period prior to the industrial user’s request for equivalent mass limits.
(2) An industrial user subject to equivalent mass limits must:
(a) Maintain and effectively operate control and treatment technologies adequate to achieve compliance with the equivalent mass limits;
(b) Continue to record the facility’s flow rates through the use of a continuous effluent flow monitoring device;
(c) Continue to record the facility’s production rates and notify the General Manager whenever production rates are expected to vary by more than 20% from its baseline production rates determined in division (C)(1)(c) of this section. Upon notification of a revised production rate, the General Manager will reassess the equivalent mass limit and revise the limit as necessary to reflect changed conditions at the facility; and
(d) Continue to employ the same or comparable water conservation methods and technologies as those implemented pursuant to division (C)(1)(a) of this section so long as it discharges under an equivalent mass limit.
(3) A General Manager which chooses to establish equivalent mass limits:
(a) Must calculate the equivalent mass limit by multiplying the actual average daily flow rate of the regulated process(es) of the industrial user by the concentration-based daily maximum and monthly average standard for the applicable categorical pretreatment standard and the appropriate unit conversion factor;
(b) Upon notification of a revised production rate, will reassess the equivalent mass limit and recalculate the limit as necessary to reflect changed conditions at the facility; and
(c) May retain the same equivalent mass limit in subsequent control mechanism terms if the industrial user’s actual average daily flow rate was reduced solely as a result of the implementation of water conservation methods and technologies, and the actual average daily flow rates used in the original calculation of the equivalent mass limit were not based on the use of dilution as a substitute for treatment pursuant to § 7.20.650. The industrial user must also be in compliance with 40 C.F.R. § 403.17 (regarding the prohibition of bypass).
(4) The General Manager may not express limits in terms of mass for pollutants such as pH, temperature, radiation, or other pollutants which cannot appropriately be expressed as mass.
(D) The General Manager may convert the mass limits of the categorical pretreatment standards at 40 C.F.R. parts 414, 419, and 455 to concentration limits for purposes of calculating limitations applicable to individual industrial users under the following conditions. When converting such limits to concentration limits, the General Manager must use the concentrations listed in the applicable subparts of 40 C.F.R. parts 414, 419, and 455 and document that dilution is not being substituted for treatment as prohibited by § 7.20.650.
(E) Equivalent limitations calculated in accordance with divisions (C), (D), (E), and (F) of this section are deemed pretreatment standards for the purposes of § 307(d) of the Act and this part. The General Manager must document how the equivalent limits were derived and make this information publicly available. Once incorporated into its control mechanism, the industrial user must comply with the equivalent limitations in lieu of the promulgated categorical standards from which the equivalent limitations were derived.
(F) Many 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 such standards are being applied, the same production or flow figure shall be used in calculating both the average and the maximum equivalent limitation.
(G) Any industrial user operating under a control mechanism incorporating equivalent mass or concentration limits calculated from a production based standard shall notify the General Manager 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 General Manager of such anticipated change will be required to meet the mass or concentration limits in its control mechanism that were based on the original estimate of the long term average production rate.
(H) When wastewater subject to a categorical pretreatment standard is mixed with wastewater not regulated by the same standard, the General Manager shall impose an alternate limit using the combined wastestream formula in 40 C.F.R. § 403.6(e).
(I) A user may obtain a variance from a categorical pretreatment standard if the user can prove, pursuant to the procedural and substantive portions of 40 C.F.R. § 403.13, that factors relating to its discharge are fundamentally different from the factors considered by EPA when developing the categorical pretreatment standard.
(J) A user may obtain a net gross adjustment to a categorical standard in accordance with 40 C.F.R. § 403.15.
(1995 Code, § 7.20.550) (Ord. 17-03, passed 3-21-2017; Ord. 15-02, passed 5-5-2015)