Chapter NR 210

NR 210.05(2)(f)2. 2. The daily maximum may not exceed 25 mg/l.

NR 210.05(2)(f)3. 3. The 30-day average percent removal may not be less than 85%.

NR 210.05(2)(g) (g) More stringent effluent limitations than those specified in pars. (a) to (f) may be imposed for any pollutant where necessary to meet water quality standards for water receiving the treated discharge.

NR 210.05(3) (3) Where the receiving water is classified as marginal surface water as defined in s. NR 104.02 (3) (b):

NR 210.05(3)(a) (a) The following effluent limits for BOD5 apply:

NR 210.05(3)(a)1. 1. The 30-day average may not exceed 20 mg/l.

NR 210.05(3)(a)2. 2. The 7-day average may not exceed 30 mg/l.

NR 210.05(3)(a)3. 3. The 30-day average percent removal may not be less than 85%.

NR 210.05(3)(b) (b) The following effluent limits for SS apply:

NR 210.05(3)(b)1. 1. The 30-day average may not exceed 20 mg/l.

NR 210.05(3)(b)2. 2. The 7-day average may not exceed 30 mg/l.

NR 210.05(3)(b)3. 3. The 30-day average percent removal may not be less than 85%.

NR 210.05(3)(c) (c) The effluent pH shall be within the range of 6.0 to 9.0.

NR 210.05(3)(d) (d) The daily minimum effluent dissolved oxygen level shall be 4.0mg/l.

NR 210.05(3)(e) (e) Upon request by the permittee, pursuant to s. NR 210.07 (4),the department may substitute the parameter CBOD5 for the parameter BOD5 and the levels of effluent quality specified in par. (a). The following effluent quality levels of CBOD5will be applicable:

NR 210.05(3)(e)1. 1. The 30-day average may not exceed 16 mg/l.

NR 210.05(3)(e)2. 2. The 7-day average may not exceed 25 mg/l.

NR 210.05(3)(e)3. 3. The 30-day average percent removal may not be less than 85%.

NR 210.05(3)(f) (f) More stringent effluent limitations than those specified in pars. (a) to (e) may be imposed for any pollutant where necessary to meet water quality standards for water receiving the treated discharge.

NR 210.05(4) (4) Effluent limitations may be imposed for pollutants other than those specified in subs. (1) to (3) where necessary to meet water quality standards for waters receiving the treated discharge.

NR 210.05(5) (5) When determining whether more stringent effluent limitations are required under this section to meet water quality standards in the receiving water or downstream waters, the department shall apply the reasonable potential procedures in s. NR 205.067.

NR 210.05 History History: Cr. Register, October, 1986, No. 370, eff. 11-1-86; CR 03-050: r. (2) (c) Register February 2004 No. 578, eff. 3-1-04; correction in (1) (intro.) made under s. 13.93 (2m) (b) 7., Stats., Register February 2004 No. 578; CR 17-002: cr. (5) Register April 2018 No. 748, eff. 5-1-18.

NR 210.06 NR 210.06 Disinfection requirements.

NR 210.06(1) (1) Disinfection requirements. Disinfection shall be required of dischargers subject to the provisions of this chapter when the department determines, based on the information identified in sub. (3), the discharge of wastewater poses a risk to human and animal health. Disinfection shall be required:

NR 210.06(1)(a) (a) From May 1 through September 30 annually to protect recreational uses, or

NR 210.06(1)(b) (b) Year-round to protect public drinking water supplies.

NR 210.06(1)(c) (c) The period during which disinfection under pars. (a) and (b) is required may be adjusted in a WPDES permit where necessary to protect human and animal health.

NR 210.06(2) (2) Effluent limitations. Where and when disinfection is required, the following effluent limitations shall apply:

NR 210.06(2)(a) (a) Bacterial indicators.

NR 210.06(2)(a)1. 1. ‘Recreation protection.’ During the period of disinfection to protect recreational uses as determined under sub. (1) (a) or (c), all of the following shall apply:

NR 210.06(2)(a)1.a. a. The geometric mean of E. coli bacteria in effluent samples collected in any calendar month may not exceed 126 counts/100 mL.

NR 210.06 Note Note: To calculate the geometric mean, a value of 1 should be used for any result of 0.

NR 210.06 Note Note: As specified in ch. NR 102, Table A, for determining attainment or compliance with bacteria criteria or limits, counts are equivalent to either colony forming units or most probable number.

NR 210.06(2)(a)1.b. b. No more than 10 percent of E. coli bacteria samples collected in any calendar month may exceed 410 counts/100 mL.

NR 210.06 Note Note: U.S. EPA developed the E. coli criteria in s. NR 102.04 (6), on which these effluent limits are based using membrane filtration to count E. coli colony forming units.

NR 210.06(2)(a)2. 2. ‘Public drinking water supply protection.’ If a facility is required to disinfect to protect public drinking water supplies outside of the recreation period specified in sub. (1) (a) or (c), it may either continue to meet the E. coli limits specified in par. (a) 1. year-round, or the geometric mean of the fecal coliform bacteria for effluent samples collected in a period of 30 consecutive days may not exceed 400 counts/100 mL.

NR 210.06(2)(b) (b) Chlorine. When chlorine is used for disinfection, the daily maximum total residual chlorine concentration of the discharge may not exceed 0.1mg/l. In addition, when chlorine is used for disinfection, a dechlorination process shall be in operation for the period during which disinfection is required.

NR 210.06 Note Note: The 0.1 mg/l total residual chlorine limit reflects best analytical technique for domestic wastewater effluents. An effluent limitation for total residual chlorine based on best available technology for dechlorination of effluents was determined to be below detection levels of currently available analytical techniques.

NR 210.06 Note Note: Compliance schedules for effluent limits established under this subsection are authorized in s. NR 205.14 and procedures are detailed in s. NR 106.117. Language on tentative and final determinations related to the permit, public notice processes, and review procedures are provided for all facilities in ch. NR 203.

NR 210.06(3) (3) Disinfection determination. A permittee subject to this chapter shall at the time of application for a WPDES permit provide information identified in this subsection which the department shall use in the determination of the need for effluent disinfection. The following information shall be used in identifying risks to human and animal health:

NR 210.06(3)(a) (a) Proximity of the wastewater outfall to swimming beaches and other waters which have a high level of human contact recreational activities.

NR 210.06(3)(b) (b) Proximity of the wastewater outfall to public drinking water supply intakes. At a minimum, whenever a drinking water intake is within a radius of 5 miles of a wastewater outfall in a lake or impoundment or within 20 miles downstream of a wastewater outfall on a flowing surface water, disinfection shall be provided.

NR 210.06(3)(c) (c) Proximity of the wastewater outfall to wetlands which support populations of waterfowl subject to disease outbreaks, which may be caused by the discharge of wastewater which has not been disinfected.

NR 210.06(3)(d) (d) Quality of the wastewater being discharged.

NR 210.06(3)(e) (e) Dilution and mixing characteristics of the wastewater with the receiving water.

NR 210.06(3)(f) (f) Bacterial indicator organism levels or sanitary survey results from sampling conducted in the vicinity of the wastewater outfall and near the sites used for recreational purposes.

NR 210.06(3)(g) (g) The classification of the receiving water and downstream waters as determined in s. NR 104.02 (1).

NR 210.06(3)(h) (h) The detention time of the wastewater treatment system. Except in extenuating circumstances, the discharge of wastewater to surface water from a treatment system with a detention time of 180 days or longer does not pose a risk to human and animal health.

NR 210.06(3)(i) (i) Other factors that are necessary to determine if there is a risk posed to human and animal health by the discharge of wastewater that has not been disinfected.

NR 210.06(7) (7) Disinfection continuation. In the absence of a specific determination under sub. (1), all dischargers which are required to disinfect as of November 1, 1986, or thereafter shall continue to disinfect.

NR 210.06 History History: Cr. Register, October, 1986, No. 370, eff. 11-1-86; CR 19-014: cr. (1) (title), (2) (title), am. (2) (intro.), r. and recr. (2) (a), cr. (2) (b) (title), (3) (title), r. (4) to (6), am. (7) Register April 2020 No. 772, eff. 5-1-20; correction in (7) made under s. 35.17, Stats., Register April 2020 No 772.

NR 210.07 NR 210.07 Effluent limitation variance categories. Modifications to limitations specified in s. NR 210.05 (1) to (3) may be approved as follows:

NR 210.07(1) (1) Industrial wastes. For publicly owned treatment facilities receiving effluent from certain categories of industries, the applicable effluent limitations for BOD5 and SS as set forth in s. NR 210.05 (1) may be modified. The limitations for BOD5 and SS in s. NR 210.05 (1) may be adjusted upwards provided that:

NR 210.07(1)(a) (a) The discharge of such pollutants attributable to the industrial category will not be greater than that allowed by applicable effluent limitations if such industrial category were to discharge directly into the waters of the state; and

NR 210.07(1)(b) (b) The flow or loading of such pollutants introduced by the industrial category exceeds 10% of the design flow or loading of the publicly owned treatment works. When such an adjustment is made, the limitations for BOD5 or SS in s. NR 210.05 (1) shall be adjusted proportionally.

NR 210.07(2) (2) Aerated lagoons and stabilization ponds. A variance for SS may be made in cases where aerated lagoons or waste stabilization ponds are the principal treatment processes. The SS limitation may be raised to a maximum of 60 mg/l for a 30-day average. This variance is not applicable to polishing or holding ponds which are preceded by other biological or physical/chemical treatment processes.

NR 210.07 Note Note: See s. NR 110.24 for design requirements of aerated lagoons and stabilization ponds.

NR 210.07(3) (3) pH. The effluent pH limitations may be adjusted on a case-by-case basis if the permittee or the owner can demonstrate that the limits need to be adjusted based on the following:

NR 210.07(3)(a) (a) Inorganic chemicals are not added as part of the treatment process; and

NR 210.07(3)(b) (b) In the case of a publicly owned treatment works, contributions from industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 9.0.

NR 210.07(4) (4) CBOD5. Upon request by the permittee, the parameter CBOD5 may be substituted for the parameter BOD5, provided the following conditions are met:

NR 210.07(4)(a) (a) For treatment facilities with BOD5 limitations specified in s. NR 210.05 (1) (a), (2) (a), or (3) (a), the permittee shall provide paired sampling of the effluent for BOD5 and CBOD5 for the months of January and July. The sample frequency shall be at the same frequency as required by the permit for BOD5 sampling. Additional sampling for nitrogen compounds (NH3-N, NO3-N) or other sampling may also be required on a case-by-case basis.

NR 210.07(4)(b) (b) For treatment facilities with BOD5 limitations established in accordance with those specified in s. NR 210.05 (1) (e), (2) (g), or (3) (f), the permittee shall provide paired sampling of the effluent for BOD5, CBOD5, NH3-N and NO3-N. At the end of the BOD5 test, an analysis of that BOD5 sample for NO3-N shall also be conducted.

NR 210.07(4)(b)1. 1. This sampling shall be provided for the months of January, February, July, and August at a frequency of 3 times weekly for facilities with a design flow over 0.5 MGD and for those facilities which discharge to trout waters or may impact trout waters.

NR 210.07(4)(b)2. 2. This sampling shall be provided for the months of January and July at a sample frequency as required by the permit for BOD5 sampling, with a maximum of 3 times weekly for facilities with a design flow less than 0.5 MGD.

NR 210.07(5) (5) Treatment equivalent to secondary treatment.

NR 210.07(5)(a) (a) Facilities eligible for treatment equivalent to secondary treatment as defined in s. NR 210.03 (6) shall provide the following minimum level of effluent quality in terms of the parameters BOD5, SS, and pH. All requirements for the specified parameters in subd. 1., 2. or 3. shall be achieved except where provided for in sub. (2) or par. (b), (c), or (d).

NR 210.07(5)(a)1. 1. The following effluent limits for BOD5 apply:

NR 210.07(5)(a)1.a. a. The 30-day average may not exceed 45 mg/l.

NR 210.07(5)(a)1.b. b. The 7-day average may not exceed 65 mg/l.

NR 210.07(5)(a)1.c. c. The 30-day average percent removal may not be less than 65%.

NR 210.07(5)(a)2. 2. The following effluent limits for SS apply: except where SS values have been adjusted in accordance with s. NR 210.07 (2):

NR 210.07(5)(a)2.a. a. The 30-day average may not exceed 45 mg/l.

NR 210.07(5)(a)2.b. b. The 7-day average may not exceed 65 mg/l.

NR 210.07(5)(a)2.c. c. The 30-day average percent removal may not be less than 65%.

NR 210.07(5)(a)3. 3. The requirements of s. NR 210.05 (1) (c) shall be met.

NR 210.07(5)(b) (b) Except as limited by par. (d) and subject to EPA approval, the department may after notice and opportunity for public comment, adjust the minimum levels of effluent quality set forth in par. (a) 1. a., b., 2. a. and b. for trickling filter facilities and in par. (a) 1. a. and b. for waste stabilization pond facilities to conform to the BOD5 and SS effluent concentrations consistently achievable through proper operation and maintenance by the median (50th percentile) facility in a representative sample of facilities within a state or appropriate contiguous geographical area that meet the definition of facilities eligible for treatment equivalent to secondary treatment.

NR 210.07(5)(c) (c) Where data are available to establish CBOD5 limitations for a treatment works subject to this subsection, the department may substitute the parameter CBOD5 for the parameter BOD5 in pars. (a) and (b), on a case-by-case basis.

NR 210.07(5)(c)1. 1. The levels of CBOD5 effluent may not be less stringent than the following:

NR 210.07(5)(c)1.a. a. The 30-day average may not exceed 40 mg/l.

NR 210.07(5)(c)1.b. b. The 7-day average may not exceed 60 mg/l.

NR 210.07(5)(c)1.c. c. The 30-day average percent removal may not be less than 65%.

NR 210.07(5)(c)2. 2. To apply for the CBOD5 variance, the permittee shall provide the data outlined in sub. (4).

NR 210.07(5)(d) (d) Any permit adjustment made pursuant to this section may not be any less stringent than the limitation required pursuant to sub. (5) (a). The department shall require more stringent limitations when adjusting permits if:

NR 210.07(5)(d)1. 1. For existing facilities the permitting authority determines that the 30-day average and 7-day average BOD5 and SS effluent values that could be achievable through proper operation and maintenance of the treatment works, based on an analysis of the past performance of the treatment works, would enable the treatment works to achieve more stringent limitations, or

NR 210.07(5)(d)2. 2. For new facilities, the department determines that the 30-day average and 7-day average BOD5 and SS effluent values that could be achievable through proper operation and maintenance of the treatment works, considering the design capability of the treatment process and geographical and climatic conditions, would enable the treatment works to achieve more stringent limitations.

NR 210.07(6) (6) Combined sewers. Treatment works which have a combined sewer system may not be capable of meeting the percentage removal requirements established in sub. (5) (a) 1. c. and 2. c. or in s. NR 210.05 (1) (a) 3. and (b) 3. during wet weather where the treatment works receive flows from combined sewers. For each treatment works, the decision shall be made on a case-by-case basis as to whether any attainable percentage removal level can be defined, and if so, what the level should be.

NR 210.07 History History: Cr. Register, October, 1986, No. 370, eff. 11-1-86.

Subchapter III — Operations, Analyses, and Reports