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(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 HistoryHistory: 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(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)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.

NR 211.13(1)(b)6.6. The granting of removal credits will not result in a discharge of pollutants to waters of the state greater than the discharge that would be allowed if the pollutants were discharged other than through a POTW.

y = x
l-r
where:
x = pollutant discharge limit specified in the applicable
categorical pretreatment standard.
r = removal credit for that pollutant as established under sub. (2) (percentage removal expressed as a proportion, i.e., a number between 0 and 1).
y = revised discharge limit for the specified pollutant
(expressed in same units as x).

NR 211.13(2)(2) Demonstration of consistent removal. In order to demonstrate consistent removal, the POTW shall, for each pollutant [for] which removal credit authorization is sought, collect influent and effluent data and calculate consistent removal in accordance with the following requirements:

NR 211.13(2)(a)(a) At least 12 representative samples of influent and effluent shall be taken at approximately equal intervals throughout one full year. Sampling shall be evenly distributed over the days of the week to include non-work days as well as work days. Upon concurrence of the department, a POTW may utilize a historical data base either in lieu of or as a supplement to these 12 samples. In order to be approved, the historical data base shall represent the yearly and seasonal conditions to which the POTW is subject and the POTW’s performance for at least one year. Alternatively, a POTW, upon approval of the department, may utilize an alternative sampling design, if the samples to be taken represent the POTW’s normal operating conditions and the different seasonal conditions to which the POTW is subject.

NR 211.13(2)(b)1.1. ‘Composite method.’

NR 211.13(2)(b)1.a.a. Influent and effluent operational data should be obtained through 24-hour flow proportional composite samples. Sampling may be done manually or automatically, and discretely or continuously. If discrete sampling is employed, at least 12 aliquots shall be composited. Discrete sampling may be flow proportioned either by varying the time interval between each aliquot or the volume of each aliquot. All composites shall be flow proportional to either the stream flow at the time of collection of the influent aliquot or to the total influent flow since the previous influent aliquot. Volatile pollutant aliquots shall be combined in the laboratory immediately before analysis.

NR 211.13(2)(b)1.b.b. Effluent sample collection need not be delayed to compensate for hydraulic detention. However, the POTW may elect to include detention time compensation or the department may require detention time compensation. The department may require that each effluent sample is taken approximately one detention time later than the corresponding influent sample if necessary to represent actual POTW operation. The detention period shall be based on a 24-hour average daily flow value. The average daily flow shall be based on the average of the daily flows during the same month of the previous year.

NR 211.13(2)(b)2.2. ‘Grab method.’ If composite sampling is not an appropriate technique, grab samples shall be taken to obtain influent and effluent operational data. A grab sample is an individual sample collected over a period of time not exceeding 15 minutes. The collection of influent grab samples shall precede the collection of effluent samples by approximately one detention period except that where the detention period is greater than 24 hours such staggering of the sample collection may not be necessary or appropriate. The detention period shall be based on a 24-hour average daily flow value. The average daily flow shall be based upon the average of the daily flows during the same month of the previous year. Grab sampling shall be employed where the pollutants being evaluated are those which may not be held for an extended period because of biological, chemical or physical interaction after sample collection which affects the results.

NR 211.13(2)(c)(c) The POTW shall analyze the samples for pollutants in accordance with the analytical techniques prescribed in ch. NR 219. If ch. NR 219 does not contain analytical techniques for the pollutant in question, or if the department determines that ch. NR 219 analytical techniques are inappropriate, the analysis shall be performed using validated analytical methods or any other applicable analytical procedures approved by the department including procedures suggested by the POTW.

NR 211.13(2)(d)1.1. For purposes of this paragraph “measurable” refers to the ability of the analytical method to quantify as well as identify the presence of the pollutant in question. “Limit of detectability” refers to the lowest limit at which the analytical method can quantify the pollutant in question.