Chapter NR 211

NR 211.03(22) (22) “WPDES permit” means a permit issued to a POTW under s. 283.31, Stats., for the purposes of controlling pollutant discharge.

NR 211.03 History History: Cr. Register, July, 1983, No. 331, eff. 8-1-83; r. (6), renum. (1) to (5) and (7) to (15) to be (2), (4), (6) to (8) and (10) to (17) and (22), cr. (1), (3), (5), (9) and (18) to (21), Register, September, 1986, No. 369, eff. 10-1-86; cr. (1m), (2e), (2s), (9m), (19m) and (20m), am. (8) and (10), r. and recr. (9), Register, March, 1992, No. 435, eff. 4-1-92; CR 13-006: cr. (1e), (4m), am. (8), cr. (8m), am. (16), (19m) (a), (c), r. (19m) (d) Register January 2014 No. 697, eff. 2-1-14; correction in (16) made under s. 13.92 (4) (b) 7., Stats., Register January 2014 No. 697.

subch. I of ch. NR 211 Subchapter I — Industrial User Requirements

NR 211.10 NR 211.10 Prohibited discharge standards.

NR 211.10(1) (1) Industrial users may not discharge pollutants into a POTW which pass through or interfere with the operation or performance of the POTW, and thereby cause or significantly contribute to a violation of the POTW’s WPDES permit.

NR 211.10(2) (2) The following pollutants may not be introduced into a POTW:

NR 211.10(2)(a) (a) Pollutants that create or contribute to a fire or explosion hazard in the POTW, including waste streams with a closed cup flashpoint of less than 140° F or 60° C using the test methods in s. NR 661.0021.

NR 211.10(2)(b) (b) Pollutants which will cause or contribute to corrosive structural damage to the POTW but in no case discharges with a pH lower than 5.0, unless the POTW is specifically designed to accommodate such discharges.

NR 211.10(2)(c) (c) Solid or viscous pollutants in amounts which will cause or contribute to obstruction to the flow in sewers or other interference with the operation of the POTW.

NR 211.10(2)(d) (d) Any pollutant, including oxygen demanding pollutants, released in a discharge of such volume or strength as to cause or contribute to interference in the POTW.

NR 211.10(2)(e) (e) Heat in amounts which will inhibit or contribute to the inhibition of biological activity in the POTW treatment plant resulting in interference or causing damage to the POTW but in no case heat in such quantities that the temperature exceeds 40°C (104°F) at the influent to the POTW treatment plant unless the department, at the request of the POTW, has approved alternate temperature limits.

NR 211.10(2)(f) (f) Petroleum oil, nonbiodegradable cutting oil or products of mineral oil origin in amounts that will cause interference or pass through.

NR 211.10(2)(g) (g) Pollutants which result in the presence of gases, vapors or fumes within the POTW in a quantity which may cause acute worker health or safety problems.

NR 211.10(2)(h) (h) Any trucked or hauled pollutants, except at discharge points designated by the POTW.

NR 211.10(3) (3) 

NR 211.10(3)(a) (a) POTWs developing pretreatment programs under subchapter II shall develop specific prohibited discharge standards to enforce the general prohibitions of subs. (1) and (2). All other POTWs shall, where the contributions of industrial users result in pass-through or interference and the resulting permit violation is likely to recur, develop and enforce specific prohibited discharge standards which, together with appropriate POTW facility or operation changes, are necessary to ensure continued compliance with the POTW’s WPDES permit.

NR 211.10(3)(b) (b) This subsection is not intended to require pretreatment as a substitute for adequate municipal treatment.

NR 211.10(3)(c) (c) Specific prohibited discharge standards may not be developed and enforced by the POTW without giving prior notice to persons or groups who have requested notice and an opportunity to respond.

NR 211.10(3)(d) (d) Where specific prohibited discharge standards or limits on pollutants or pollutant parameters are developed by a POTW under this subsection, they shall be deemed pretreatment standards for the purposes of s. 283.21 (2), Stats.

NR 211.10(3)(e) (e) POTWs may develop best management practices to implement the prohibitions of subs. (1) and (2). Such BMPs shall be considered specific prohibited discharge standards under this subsection and pretreatment standards for the purposes of s. 283.21 (2), Stats.

NR 211.10(4) (4) Except where expressly authorized to do so by an applicable pretreatment standard or requirement, no industrial user may increase the use of process water or in any other way attempt to dilute a discharge as a partial or complete substitute for adequate treatment to achieve compliance with a pretreatment standard or requirement. The control authority may impose mass limitations on an industrial user to account for dilution or in any other situation for which the control authority finds mass limitations appropriate.

NR 211.10 History History: Cr. Register, July, 1983, No. 331, eff. 8-1-83; r. (1) (a) and (b), am. (2) (a), cr. (2) (f) to (h) and (4), Register, March, 1992, No. 435, eff. 4-1-92; correction in (2) (a) made under s. 13.92 (4) (b) 7., Stats., Register May 2011 No. 665; CR 13-006: am. (3) (d), cr. (3) (e) Register January 2014 No. 697, eff. 2-1-14; CR 19-082: am. (2) (a) Register July 2020 No. 775, eff. 8-1-20.

NR 211.11 NR 211.11 Categorical pretreatment standards.

NR 211.11(1) (1) Categorical pretreatment standards for specific point source categories are set forth in chs. NR 221 to 297. Limits in categorical pretreatment standards shall apply to the effluent from the process regulated by the standard, unless otherwise specified in the standard. Limits in categorical pretreatment standards shall apply to wastestreams which are transported off-site for disposal as well as those discharged on-site. Industrial users shall comply with applicable categorical pretreatment standards, in addition to complying with the general prohibitions established in s. NR 211.10, unless specifically noted otherwise in the categorical pretreatment standard.

NR 211.11(2) (2) Compliance dates.

NR 211.11(2)(a) (a) All industrial users, except new sources, shall comply with the applicable categorical pretreatment standards within 3 years from the effective date of the standard or within a shorter time period if specified in the applicable standard. A direct discharger which becomes an industrial user after promulgation of an applicable categorical pretreatment standard may not be considered a new source unless it falls within the definition of a “new source”contained in s. NR 211.03 (9).

NR 211.11(2)(b) (b) New sources shall install, have in operating condition and start up all of the pollution control equipment required to meet the applicable pretreatment standards before beginning discharge. Within the shortest feasible time, not to exceed 90 days, new sources shall meet all applicable pretreatment standards.

NR 211.11(3) (3) Conversion to equivalent mass or concentration standards.

NR 211.11(3)(a) (a)

NR 211.11(3)(a)1. 1. When the limits in a categorical pretreatment standard are expressed only in terms of mass of pollutant per unit of production, the control authority may convert the limits to equivalent limitations expressed either as mass of pollutant discharged per day or effluent concentration for purposes of calculating limits for individual users.

NR 211.11(3)(a)2. 2. Equivalent mass per day limits shall be calculated by multiplying the limits in the standard by the industrial user’s average rate of production. This average rate of production shall be based upon a reasonable measure of the industrial user’s actual long-term daily production, such as average daily production, during a representative year. For new sources, actual production shall be estimated using projected production.

NR 211.11(3)(a)3. 3. Equivalent concentration limits shall be calculated by dividing the mass limits derived according to subd. 2. by the average daily flow rate of the industrial user’s 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 same representative year used in subd. 2.

NR 211.11(3)(a)4. 4. When pretreatment standards specify both daily and long-term limits, the same production or flow figures shall be used in calculating daily and long-term equivalent limits.

NR 211.11(3)(a)5. 5. Any industrial user operating under a control mechanism incorporating equivalent mass or concentration limits calculated from a production based standard shall notify the control authority within 2 business days after the industrial user has reason to know that the production level will significantly change within the next calendar month. Any industrial user which does not notify the control authority of such anticipated change shall meet the mass or concentration limits in its control mechanism that were based on the original estimate of the long-term average production rate.

NR 211.11(3)(bm) (bm)

NR 211.11(3)(bm)1. 1. When the limits in a categorical pretreatment standard are expressed only in terms of pollutant concentrations, an industrial user may request that the control authority convert the limits to equivalent mass limits. The determination to convert concentration limits to mass limits is within the discretion of the control authority. The control authority may establish equivalent mass limits only if the industrial user:

NR 211.11(3)(bm)1.a. a. Employs or demonstrates that it will employ water conservation methods and technologies that substantially reduce water use during the term of its control mechanism;

NR 211.11(3)(bm)1.b. b. Uses control and treatment technologies that are adequate to achieve compliance with the applicable categorical pretreatment standard, and has not used dilution as a substitute for treatment;

NR 211.11(3)(bm)1.c. c. Provides sufficient information to establish the facility’s actual average daily flow rate for all waste streams, 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 shall be representative of current operating conditions;

NR 211.11(3)(bm)1.d. d. Does 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

NR 211.11(3)(bm)1.e. e. Has consistently complied with all applicable categorical pretreatment standards during the period prior to the industrial user’s request for equivalent mass limits.

NR 211.11(3)(bm)2. 2. Upon approval by the control authority an industrial user subject to equivalent mass limits shall:

NR 211.11(3)(bm)2.a. a. Maintain and effectively operate control and treatment technologies adequate to achieve compliance with the equivalent mass limits;

NR 211.11(3)(bm)2.b. b. Continue to record the facility’s flow rates through the use of a continuous effluent flow monitoring device;

NR 211.11(3)(bm)2.c. c. Continue to record the facility’s production rates and notify the control authority whenever production rates are expected to vary by more than 20 percent from its baseline production rates determined in subd. 1. c. Upon notification of a revised production rate, the control authority shall reassess the equivalent mass limit and revise the limit as necessary to reflect changed conditions at the facility; and

NR 211.11(3)(bm)2.d. d. Continue to employ the same or comparable water conservation methods and technologies as those implemented pursuant to subd. 1. a. so long as it discharges under an equivalent mass limit.

NR 211.11(3)(bm)3. 3. A control authority which chooses to establish equivalent mass limits:

NR 211.11(3)(bm)3.a. a. Shall calculate the equivalent mass limit by multiplying the actual average daily flow rate of the regulated processes by the concentration-based daily maximum and monthly average standard for the applicable categorical pretreatment standard and the appropriate unit conversion factor;

NR 211.11(3)(bm)3.b. b. Upon notification of a revised production rate, shall reassess the equivalent mass limit and recalculate the limit as necessary to reflect changed conditions at the facility; and

NR 211.11(3)(bm)3.c. 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 as prohibited by s. NR 211.10 (4). The industrial user shall also be in compliance with s. NR 211.19.

NR 211.11(3)(bm)4. 4. A control authority 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.

NR 211.11(3)(cm) (cm) The control authority may convert the mass limits of the categorical pretreatment standards in chs. NR 233, 235, and 279 to equivalent concentration limits. When converting such limits to concentration limits, the control authority shall use the concentrations listed in the applicable subparts of chs. NR 233, 235, and 279 and document that dilution is not being substituted for treatment as prohibited by s. NR 211.10 (4).

NR 211.11(3)(d) (d) Equivalent limitations calculated in accordance with par. (a), (bm), or (cm) are deemed pretreatment standards for the purposes of this chapter and s. 283.21 (2), Stats. The control authority shall document how the equivalent limits were derived and make this information available to the public. Once incorporated into its control mechanism, the industrial user shall comply with the equivalent limitations in lieu of the promulgated categorical standards from which the equivalent limitations were derived.

NR 211.11(3)(e) (e) When pretreatment standards specify both maximum daily and maximum average limits, the same production or flow figures shall be used in calculating maximum daily and maximum average limits.

NR 211.11(4) (4) Compensation for pollutants in intake water.

NR 211.11(4)(a) (a) Categorical pretreatment standards may be adjusted to reflect the presence of pollutants in an industrial user’s intake water if the applicable categorical pretreatment standards specifically provide that they may be applied on a net basis or if the industrial user demonstrates to the control authority that:

NR 211.11(4)(a)1. 1. The control system used or proposed to meet the categorical pretreatment standards would meet the categorical pretreatment standards in the absence of pollutants in the intake water if the control system is properly installed and operated;

NR 211.11(4)(a)2. 2. The constituents of a generic measure, such as BOD, TSS or oil and grease, in the industrial user’s effluent are substantially similar to the constituents of the generic measure in the intake water. The control authority may waive this requirement if appropriate additional limits are placed on process water pollutants either at the point of discharge or elsewhere; and

NR 211.11(4)(a)3. 3. The intake water is drawn from the same water body as the water body to which the POTW discharges. The control authority may waive this requirement if it finds that no environmental de-gradation will result.

NR 211.11(4)(b) (b) The control authority shall grant credits only to the extent necessary to meet the applicable categorical pretreatment standards, up to a maximum value equal to the influent value. The control authority may require additional monitoring to determine eligibility for credits and compliance with the adjusted standards.

NR 211.11 History History: Cr. Register, July, 1983, No. 331, eff. 8-1-83; am. (1), r. and recr. (2) and (3), cr. (4), Register, March, 1992, No. 435, eff. 4-1-92; CR 13-006: am. (3) (title), cr. (3) (a) 5., r. (3) (b), cr. (3) (bm), r. (3) (c), cr. (3) (cm), (d), (e), am. (4) (a) (intro.) Register January 2014 No. 697, eff. 2-1-14.

NR 211.12 NR 211.12 Combined wastestreams.

NR 211.12(1) (1) Where effluent from a process regulated by a categorical pretreatment standard is mixed prior to treatment with wastewaters other than those generated by the regulated process, fixed alternative discharge limits may be established by the control authority or by the industrial user with the written concurrence of the control authority. These alternative limits shall apply to the mixed effluent. When deriving alternative categorical limits, the control authority or industrial user shall calculate both an alternative daily maximum value using the daily maximum values specified in the appropriate categorical pretreatment standards and an alternative monthly average value using the monthly average values specified in the appropriate categorical pretreatment standards. The industrial user shall comply with the alternative daily maximum and monthly average limits approved by the control authority until the control authority modifies the limits or approves an industrial user modification request. Modification is authorized whenever there is a material or significant change in the values used in the calculation to fix alternative limits for the regulated pollutant. An industrial user shall immediately report any such material or significant change to the control authority. New alternative categorical limits shall be calculated within 30 days.

NR 211.12(2) (2) Alternative limit calculation. Alternative limits shall be derived according to the following formulas:

NR 211.12(2)(a) (a) Alternative concentration limit:

NR 211.12(2)(b) (b) Alternative mass limit:

NR 211.12(2)(c) (c) Where:

NR 211.12(2)(c)1. 1. Boiler blowdown, non-contact cooling, stormwater and demineralizer backwash streams. However, if these streams contain a significant amount of a pollutant and if the combination of these streams with an industrial user’s regulated process waste-stream prior to treatment will result in a substantial reduction of that pollutant, the control authority, upon the industrial user’s application, shall determine whether these streams should be classified as diluted or unregulated. In its application to the control authority, the industrial user shall provide engineering, production, sampling and analysis and other information necessary for the control authority to make its determinations;

NR 211.12(2)(c)2. 2. Sanitary wastestreams where the streams are not regulated by a categorical pretreatment standard; or

NR 211.12(2)(c)3. 3. Any process wastestreams which were or could have been entirely exempted from categorical pretreatment standards for one or more of the following reasons:

NR 211.12(2)(c)3.a. a. The pollutants regulated by the categorical pretreatment standards used in the formula are not detectable in the effluent from the industrial user;

NR 211.12(2)(c)3.b. b. The pollutants of concern are present only in trace amounts and are neither causing nor likely to cause toxic effects;

NR 211.12(2)(c)3.c. c. The pollutants of concern are present in amounts too small to be effectively reduced by technologies known to the administrator of EPA; or

NR 211.12(2)(c)3.d. d. The wastestream contains only pollutants that are compatible with the POTW.

NR 211.12(3) (3) Alternate limits below detection limit. An alternative pretreatment limit may not be used if the alternative limit is below the analytical detection limit for any of the regulated pollutants.

NR 211.12(4) (4) Self-monitoring. Self-monitoring to insure compliance with the alternative categorical limit shall be conducted in accordance with s. NR 211.15 (4).

NR 211.12(5) (5) Choice of monitoring location.

NR 211.12(5)(a) (a) If a treated regulated process wastestream is combined with wastewaters other than those generated by the regulated process, the industrial user may monitor either the segregated process wastestream or the combined wastestream for purposes of determining compliance with the applicable pretreatment standards. If the industrial user chooses to monitor the segregated process wastestream, the industrial user shall apply the applicable categorical pretreatment standard. If the industrial user chooses to monitor the combined wastestream, the industrial user shall apply an alternative discharge limit calculated according to the combined wastestream formula in sub. (2).

NR 211.12(5)(b) (b) An industrial user may change monitoring points only after receiving approval from the control authority. The control authority shall ensure that any change in an industrial user’s monitoring point will not allow the industrial user to substitute dilution for adequate treatment.

NR 211.12 History History: Cr. Register, September, 1986, No. 369, eff. 10-1-86; am. (1), r. and recr. (2) and (4), cr. (5) and (6), Register, March, 1992, No. 435, eff. 4-1-92; CR 13-006: r. (6) Register January 2014 No. 697, eff. 2-1-14.

NR 211.13 NR 211.13 Removal credits.

NR 211.13(1) (1) 

NR 211.13(1)(a) (a) Any POTW receiving wastes from an industrial user to which a categorical pretreatment standard applies may, subject to the conditions of this section, grant removal credits for removal by the POTW of pollutants specified in the categorical pretreatment standard. The POTW may grant a removal credit equal to or less than its consistent removal rate. Upon being granted a removal credit, each affected industrial user shall calculate its revised discharge limits in accordance with par. (c).

NR 211.13(1)(b) (b) A POTW may give removal credits only if:

NR 211.13(1)(b)1. 1. The POTW applies for and receives authorization from the department to give a removal credit in accordance with the requirements and procedures specified in sub. (5). Removal credits may only be given for indicator or surrogate pollutants regulated in a categorical pretreatment standard if the categorical pretreatment standard so specifies.

NR 211.13(1)(b)2. 2. The POTW demonstrates and continues to achieve consistent removal of the pollutant in accordance with sub. (2).

NR 211.13(1)(b)3. 3. Except as provided in sub. (7), the POTW has an approved pretreatment program as required by this chapter; however, a POTW which does not have an approved pretreatment program may, pending approval of such a program, conditionally give credits as provided in sub. (4).

NR 211.13(1)(b)4. 4. The granting of removal credits will not cause the POTW to violate the local, state and federal sludge requirements which apply to the sludge management method chosen by the POTW. Alternatively, the POTW can demonstrate to the department that even though it is not presently in compliance with applicable sludge requirements, it will be in compliance when the industrial user to whom the removal credit would apply is required to meet its modified categorical pretreatment standard.

NR 211.13(1)(b)5. 5. The granting of removal credits will not cause a violation of the POTW’s permit limitations or conditions. Alternatively, the POTW can demonstrate to the department that even though it is not presently in compliance with applicable limitations and conditions in its WPDES permit, it will be in compliance when the industrial user to whom the removal credit would apply is required to meet its modified categorical pretreatment standard.