Section 210.06. Disinfection requirements.

 

(1)  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:

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

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

(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.

(2)  Where disinfection is required, the following effluent limitations shall apply:

(a) The geometric mean of the fecal coliform bacteria for effluent samples collected in a period of 30 consecutive days may not exceed 400mg/100 ml.

(b) 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.

(3)  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:

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

(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.

(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.

(d) Quality of the wastewater being discharged.

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

(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.

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

(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.

(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.

(4)  Permittees shall be given a reasonable compliance schedule in their WPDES permit if they are unable to meet the effluent limits contained in s. NR 210.06 (2) at the time of permit issuance. However, in no case may the date for compliance with sub. (2) extend beyond 3 years from the date of permit issuance, unless circumstances beyond the permittee's control, such as an environmental impact statement, require additional time for compliance. In such circumstances the date for compliance with sub. (2) may not extend beyond 5 years from the date of permit issuance.

(5)  Final determinations made under subs. (1) and (4) shall be made at the time of permit issuance, reissuance, or in response to a request for modification of an existing permit.

(6)  The department shall include in the public notice issued under s. 283.39 , Stats., its tentative determinations made under subs. (1) and (4) . Those tentative determinations shall be subject to review under s. 283.49 , Stats. Final determinations made under subs. (1) and (4) shall be subject to review under s. 283.63 , Stats. Tentative determinations and final determinations made under subs. (1) and (4) are not subject to review under s. 283.15 , Stats.

(7)  In the absence of a specific determination under sub. (1) , all dischargers which are required to disinfect as of the effective date of this rule shall continue to disinfect and comply with all terms of their WPDES permit in effect on that date.

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

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. Microsoft Windows NT 6.1.7601 Service Pack 1