Users must comply with the categorical pretreatment standards found at 40 C.F.R. Chapter I, Subchapter N, parts 405-471.
(A) Where a categorical pretreatment standard is expressed only in terms of either the mass or the concentration of a pollutant in wastewater, the Superintendent may impose equivalent concentration or mass limits in accordance with § 54.021(E) and (F).
(B) 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.
(C) When wastewater subject to a categorical pretreatment standard is mixed with wastewater not regulated by the same standard, the Superintendent shall impose an alternate limit in accordance with 40 C.F.R. § 403.6(e).
(D) A CIU may obtain a net/gross adjustment to a categorical pretreatment standard in accordance with the following divisions (E) through (H) below.
(1) Categorical pretreatment standards may be adjusted to reflect the presence of pollutants in the industrial user’s intake water in accordance with this section. Any industrial user wishing to obtain credit for intake pollutants must make application to the town. Upon request of the industrial user, the applicable standard will be calculated on a “net” basis (i.e., adjusted to reflect credit for pollutants in the intake water) if the requirements of division (D)(2) below are met.
(2) Criteria:
(a) Either:
1. The applicable categorical pretreatment standards contained in 40 C.F.R. Subchapter N specifically provide that they shall be applied on a net basis; or
2. The industrial user demonstrates that the control system it proposes or uses to meet applicable categorical pretreatment standards would, if properly installed and operated, meet the standards in the absence of pollutants in the intake waters.
(b) Credit for generic pollutants such as biochemical oxygen demand (BOD), total suspended solids (TSS) and oil and grease should not be granted unless the industrial user demonstrates that the constituents of the generic measure in the user’s effluent are substantially similar to the constituents of the generic measure in the intake water or unless appropriate additional limits are placed on process water pollutants either at the outfall or elsewhere.
(c) Credit shall be granted only to the extent necessary to meet the applicable categorical pretreatment standard(s), up to a maximum value equal to the influent value. Additional monitoring may be necessary to determine eligibility for credits and compliance with standard(s) adjusted under this section.
(d) Credit shall be granted only if the user demonstrates that the intake water is drawn from the same body of water as that into which the POTW discharges. The town may waive this requirement if it finds that no environmental degradation will result.
(E) (1) The Superintendent may convert the mass limits of the categorical pretreatment standards of 40 C.F.R. parts 414, 419 and 455 to concentration limits for purposes of calculating limitations applicable to individual industrial users. The conversion is at the discretion of the Superintendent.
(2) Note: When converting such limits to concentration limits, the Superintendent will 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 § 54.025 (see 40 C.F.R. § 403.6(d)). In addition, the Superintendent will document how the equivalent limits were derived for any changes from concentration to mass limits, or vice versa, and make this information publicly available (see 40 C.F.R. § 403.6(c)(7)).
(F) Once included in its permit, the industrial user must comply with the equivalent limitations developed in this § 54.021 in lieu of the promulgated categorical standards from which the equivalent limitations were derived.
(G) 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.
(H) Any industrial user operating under a permit incorporating equivalent mass or 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 permit that were based on the original estimate of the long term average production rate.
(Ord. 2021-03, passed 6-14-2021)