Section NR 106.98 - Determination of the necessity for reducing PFOS and PFOA in discharges(1) GENERAL. This section establishes the procedures for determining when a permitted discharge has the reasonable potential to cause or contribute to an exceedance of the PFOS or PFOA standards under s. NR 102.04 (8) (d) 1.(2) DATA GENERATION. At the first reissuance of a WPDES permit after August 1, 2022, the department shall require in the reissued permit that the permittee monitor and report PFOS and PFOA at the frequencies and locations specified under this subsection, for up to 2 years, except if a waiver has been granted or reduced frequency is approved under sub. (3). All samples shall be collected and analyzed consistent with the requirements under ch. NR 219 and s. NR 106.995. The following sample frequencies apply to each category of permitted dischargers: (a) For a major municipal discharger with an average flow rate greater than or equal to 5 million gallons per day, the permittee shall, at a minimum, sample its effluent on a monthly basis. Influent monitoring will be determined on a case-by-case basis and shall be conducted at a frequency specified in the permit.(b) For a major municipal discharger with an average flow rate greater than or equal to one million gallons per day but less than 5 million gallons per day, the permittee shall, at a minimum, sample its effluent once every 2 months. Influent monitoring will be determined on a case-by-case basis and shall be conducted at a frequency specified in the permit.(c) For all other municipal dischargers, the permittee may only be required to sample for PFOS or PFOA if the department determines that PFOS or PFOA may be present in the discharge. In making this determination, the department shall consider the presence of potential PFOS or PFOA industrial wastes to the treatment works, the presence of nearby PFOS or PFOA remediation sites, and the presence of other potential sources of PFOS or PFOA that may contribute to any part of the minor municipal discharger. If the department determines that PFOA or PFOS may be present in the discharge, the department shall require that the permittee sample its influent and effluent at a frequency specified in the permit.(d) For a primary or secondary industrial discharger, if the department determines that the permittee's effluent may contain PFOS or PFOA, the department shall require that the permittee sample its effluent at least monthly.(e) The department may require PFOS or PFOA monitoring for other discharges not included in one of the categories specified under pars. (a) to (d) if the department has a reasonable expectation that the discharge contains PFOS or PFOA at levels that will likely cause or contribute to an exceedance of the criteria under s. NR 102.04 (8) (d) 1. Note: The department has authority to sample the effluent from permitted facilities under s. 283.55, Stats.
Note: The department has authority under s. NR 205.066 (1) to specify monitoring frequency for PFOS and PFOA in WPDES permits at its discretion on a case-by-case basis after 24 months.
(3) REDUCED SAMPLE FREQUENCY AND WAIVER.(a) The department may reduce monitoring frequency to once every 3 months for dischargers described under sub. (2) (a), (b) or (d) on a case-by-case basis, but only after at least 12 representative results have been generated.(b) The department may waive the requirement to conduct PFOS or PFOA sampling for a discharger under sub. (2) if the department determines that it is unlikely that the permittee's effluent will contain PFOS or PFOA at levels above the criteria in s. NR 102.04 (8) (d) 1. Any approved waivers shall be reviewed at each permit reissuance to determine whether any changes were made at the permitted facility or when the department becomes aware of new information that may result in new or increased discharges of PFOS or PFOA, in which case monitoring may be required.(4) DETERMINATION OF THE NEED FOR A PFOS AND PFOA MINIMIZATION PLAN. The department shall require creation and implementation of a PFOS and PFOA minimization plan that meets the requirements under s. NR 106.99 as a condition of a WPDES permit whenever the department determines that the discharge from the permitted facility contains PFOS or PFOA at concentrations that have reasonable potential to cause or contribute to an exceedance of the PFOS or PFOA standard in s. NR 102.04 (8) (d) 1. When determining whether a permitted discharge has the reasonable potential to cause or contribute to an exceedance of the PFOS or PFOA standard in s. NR 102.04 (8) (d) 1., the department shall use the methods in this subsection to make the determination and shall use representative data that meet the sampling and analysis requirements under ch. NR 219 and s. NR 106.995. When making a reasonable potential determination for a permitted discharge of PFOS or PFOA under this subsection, the department shall consider whether the intake provisions in s. NR 106.06 (6) (b) apply to the discharge. When calculating a water quality based effluent limitation for PFOS in the reasonable potential determination, the department shall apply the requirements in s. NR 106.06 (1) and (6) in the calculation and shall use the applicable PFOS criterion in s. NR 102.04 (8) (d) 1. A mixing zone under s. NR 106.06 (2) may not be included in the limit calculation for a discharge of PFOS. When calculating a water quality based effluent limitation for PFOA in the reasonable potential determination, the department shall apply the requirements in s. NR 106.06 (1) and (4) to (11) in the calculation and shall use the applicable PFOA criterion in s. NR 102.04 (8) (d) 1. If any one of the following methods indicate that there is reasonable potential for an exceedance of either the PFOS or PFOA standard, a PFOS and PFOA minimization plan shall be required in the permit: (a) If at least 11 daily discharge concentrations of the substance are greater than the limit of detection, a PFOS and PFOA minimization plan is required for a permitted facility if the upper 99th percentile of the 30-day average discharge concentrations for PFOS or PFOA exceeds the applicable water quality based effluent limitation calculated under this subsection. To calculate upper 99th percentile values of the daily discharge concentrations, one of the following shall be used: 1. If a log normal probability distribution is determined to be appropriate, the upper 99th percentile of the 30-day average discharge concentrations may be calculated using the equation under s. NR 106.05 (5) (a).2. If a probability distribution other than log normal is determined to be more appropriate and alternate methods are available, those methods may be used to calculate the upper 99th percentile.(b) If fewer than 11 daily discharge concentrations of the substance are greater than the limit of detection, a PFOS and PFOA minimization plan is required for a permitted facility if the arithmetic average discharge concentration exceeds one-fifth of the applicable water quality based effluent limitation calculated under this subsection. The arithmetic average discharge concentration shall be calculated using all available representative discharge data, applying the following principles: 1. If, in the judgment of the department, the analytical methods used to test for the substance represent acceptable methods, all values reported as less than the limit of detection shall be set equal to zero for calculation of the average concentration.2. If, in the judgment of the department, the analytical methods used to test for the substance do not represent the best acceptable methods, all values reported as less than the limit of detection shall be discarded from the data.Wis. Admin. Code Department of Natural Resources § NR 106.98
Adopted by, CR 21-083: cr. Register July 2022 No. 799, eff. 8/1/2022.