Section 106.33. Determination of the necessity for water quality-based effluent limits for ammonia.

 

(1)   Reasonable potential.

(a) For a permitted discharge that is not already subject to an ammonia water quality-based effluent limitation, the procedures specified in s. NR 106.05 shall be used to determine if water quality-based effluent limitations for ammonia are necessary in a reissued permit. When application of the procedures in s. NR 106.05 results in a determination that ammonia effluent limits are not necessary in a permit, the permit holder shall continue to be operated in a manner that optimizes the removal of ammonia within the design capabilities of the wastewater treatment plant. The department may require that the permittee monitor ammonia at a frequency established on a case-by-case basis in its permit for the purpose of determining representative discharge levels.

(b) If a permittee is subject to an ammonia limitation in an existing permit, the limitation shall be included in any reissued permit. Ammonia limitations shall be included in the permit if the permitted facility will be providing treatment for ammonia discharges.

(2)   Permit limitations for continuous POTWs. The procedures for expressing limitations in permits in this subsection apply to continuous discharges subject to ch. NR 210 when there is reasonable potential under s. NR 106.05 to exceed an ammonia limitation. Both a weekly average and monthly average permit limitations shall be included in a permit for ammonia whenever any water quality-based effluent limitation for ammonia is determined necessary under sub. (1) . A daily maximum limitation shall be included in permits in addition to weekly average and monthly average limitations if necessary under sub. (1) . The department shall use all of the following procedures to include weekly average and monthly average limitations in permits:

(a) If a daily maximum limitation is the only ammonia limitation determined necessary under sub. (1) , a weekly average limitation shall be set equal to the WQBEL based on the 4-day chronic toxicity criteria calculated under s. NR 106.32 (3) or the daily maximum limitation, whichever is more restrictive.

(b) If a weekly average ammonia limitation is determined necessary under sub. (1) , and a monthly average limitation is not already determined necessary, a monthly average limitation shall be set equal to the WQBEL based on the 30-day chronic toxicity criteria calculated under s. NR 106.32 (3) or the weekly average limitation, whichever is more restrictive, except as provided under par. (c) .

(c) The department may on a case-by-case basis use an alternative methodology for calculating monthly average limitations whenever historical flow data or real time data are used to calculate weekly average limitations under s. NR 106.32 (3) (c) 2. and these limitations are determined to be necessary under sub. (1) .

(d) If a monthly average limitation is the only ammonia limitation determined to be necessary under sub. (1) , weekly average limitations shall be set equal to the WQBEL based on the 4-day chronic toxicity criteria calculated under s. NR 106.32 (3) or a weekly average limitation calculated using the following procedure, whichever is more restrictive:

Weekly Average Limitation = (Monthly Average Limitation x MF) - See PDF for table

(3)   Permit limitations for other continuous discharges. The procedures for expressing limitations in this subsection apply to continuous discharges that are not subject to ch. NR 210 and when there is reasonable potential under s. NR 106.05 to exceed an ammonia limitation. Both a daily maximum and monthly average permit limitation shall be included in a permit for ammonia whenever any water quality-based effluent limitation for ammonia is determined necessary under s. NR 106.05 . A weekly average limitation shall be included in permits in addition to a daily maximum and monthly average limitation if necessary under sub. (1) . The department shall use all of the following procedures to include daily maximum and monthly average limitations in permits:

(a) If a weekly average limitation is the only ammonia limitation determined necessary under sub. (1) , a monthly average limitation shall be set equal to the WQBEL based on the 30-day chronic toxicity criteria or the weekly average limitation, whichever is more restrictive except as provided in par. (c) . A daily maximum limitation shall also be included in the permit and set equal to the daily maximum ammonia WQBEL under s. NR 106.32 (2) or a daily maximum limitation calculated using the following procedure, whichever is more restrictive:

Daily Maximum Limitation= Weekly Average Limitation x DMF - See PDF for table

(b) If a daily maximum ammonia limitation is determined necessary under sub. (1) , and a monthly average limitation is not already determined necessary, a monthly average limitation shall be set equal to the WQBEL based on the 30-day chronic toxicity criteria calculated according to s. NR 106.32 (3) or the daily maximum limitation, whichever is more restrictive, except as provided in par. (c) .

(c) The department may on a case-by-case basis use an alternative methodology for calculating daily maximum or monthly average limitations whenever historical flow data or real time data are used to calculate weekly average limitations under s. NR 106.32 (3) (c) 2. and these limitations are determined to be necessary under sub. (1) .

(d) If a monthly average limitation is determined necessary and a daily maximum limitation is not already determined necessary under sub. (1) , a daily maximum limitation shall be set equal to the daily maximum ammonia WQBEL under s. NR 106.32 (2) or a daily maximum limitation calculated using the following procedure, whichever is more restrictive:

Daily Maximum Limitation = (Monthly Average Limitation x MF) - See PDF for table

(4)   Permit limitations for noncontinuous discharges. The department shall include ammonia water quality-based effluent permit limitations in permits for seasonal discharges, discharges proportional to stream flow, or other unusual discharge situations that do not meet the definition of a continuous discharge whenever ammonia water quality-based effluent limitations are determined necessary under sub. (1) . Ammonia limitations shall be expressed in accordance with s. NR 106.32 (5) unless the department determines on a case-by-case basis that an alternative averaging period is appropriate. The department shall consider all of the following when making a case-by-case determination:

(a) Frequency and duration of discharge.

(b) Total mass of discharge.

(c) Maximum flow rate of discharge.

(d) Whether ammonia is subject to a technology-based limitation or other limitation expressed by mass, concentration, or other appropriate measure in the permit.

CR 03-050 : cr. Register February 2004 No. 578 , eff. 3-1-04; CR 15-085 : r. and recr. Register August 2016 No. 728 , eff. 9-1-16; correction in (3) (a), (b), (d) made under s. 35.17 , Stats., Register August 2016 No. 728 .