10.20.100 Limitations on wastewater strength.
(1) Federal Categorical Pretreatment Standards. Users subject to categorical pretreatment standards are required to comply with applicable standards as set out in 40 C.F.R. Chapter 1, Subchapter N, Parts 405 through 471 and incorporated herein.
(a) When the limits in a categorical pretreatment standard are expressed only in terms of mass of pollutant per unit of production, the Director 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, in accordance with subsection (1)(b) of this section.
(b) The Director 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 Director. When converting any mass limits to concentration limits, documentation will be made that dilution is not being substituted for treatment as prohibited by subsection (4) of this section. The Director will document how the equivalent limits were derived for any changes from mass limits to concentration and make this information publicly available upon request.
(c) Once included in its permit, the industrial user must comply with the equivalent limitations developed in this section in lieu of the promulgated categorical standards from which the equivalent limitations were derived.
(d) 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.
(e) Any industrial user operating under a permit incorporating equivalent mass or concentration limits calculated from a production-based standard shall notify the Director 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 Director 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.
(2) State Requirements. State requirements and limitations on users of the POTW shall be met by all users that are subject to such standards in any instance in which they are more stringent than Federal requirements and limitations, or those in this chapter or any other applicable ordinance.
(3) Right of Revision. The City reserves the right to amend this chapter to provide for more stringent limitations or requirements on discharges to the POTW where deemed necessary to comply with the objectives set forth in MMC 10.20.010 through 10.20.060.
(4) Dilution. No user shall increase the use of potable or process water in any way for the purpose of diluting a discharge as a partial or complete substitute for adequate treatment to achieve compliance with the applicable standards set forth in this chapter. The City may impose mass limitations on users that are using dilutions to meet the applicable pretreatment standards or requirements of this chapter.
(5) Specific Pollutant Limitations.
(a) No nondomestic user shall discharge wastewater containing restricted substances into the POTW in excess of limitations specified in its wastewater discharge permit or published by the Director. The Director shall publish and revise from time to time standards for specific restricted substances, termed local limits, including designation of affected nondomestic users. These standards shall be developed in accordance with 40 C.F.R. § 403.5 and shall implement the objectives of this chapter. Standards published in accordance with this section will be deemed pretreatment standards for the purposes of § 307(d) of the Act.
(b) The Director may develop best management practices (BMPs), by ordinance or in individual wastewater discharge permits, to implement local limits and the requirements of MMC 10.20.090.
(c) The Director may impose mass limitations in addition to or in place of the concentration limits referenced above. (Ord. 106 § 4(2), passed 10-9-2012; Code 2014 § 52.04(B))