Chapter NR 811

NR 811.853(4)(c) (c) The detention tank supernatant shall be discharged to a sanitary sewer, water of the state, or holding tank and shall meet the provisions under s. NR 811.85 (1) or shall be returned to the water treatment plant in accordance with the requirements under s. NR 811.862. If discharged to a water of the state, pumps shall be provided to discharge the supernatant over approximately a 24-hour period.

NR 811.853(4)(d) (d) Settled sludge removed from detention tanks shall be disposed of at a wastewater treatment plant unless the department approves an alternate disposal location on a case-by-case basis. The disposal of sludge shall meet the applicable requirements under s. NR 811.85 (1).

NR 811.853 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: cr. (intro.), am. (1), (2) (a), (d), r. and recr. (2) (g), am. (3) (b), r. and recr. (3) (d), cr. (3) (e), am. (4) (b), r. and recr. (4) (c), am. (4) (d) Register January 2024 No. 817, eff. 2-1-24.

NR 811.854 NR 811.854 Brine wastes from ion exchange plants. Brine wastes from ion exchange processes may be discharged to a water of the state subject to the requirements under s. NR 811.85 (1) (b). An equalization tank of sufficient size to allow brine discharge over at least a 24-hour period shall be provided. The department may approve a smaller tank or no equalization if the water system facility demonstrates to the department that reduced equalization is unnecessary to prevent toxicity to aquatic life.

NR 811.854 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: r. and recr. Register January 2024 No. 817, eff. 2-1-24.

NR 811.855 NR 811.855 Wastewater from reverse osmosis plants. Reject, backwash, and concentrate wastewaters from reverse osmosis processes may be discharged to a water of the state subject to the requirements under s. NR 811.85 (1) (b). Chemical cleaning waste shall not be discharged to a water of the state. An equalization tank of sufficient size to allow discharge over at least a 24-hour period shall be provided for a surface water discharge. The department may approve a smaller tank or no equalization if the waterworks facility demonstrates to the department that reduced equalization is unnecessary to prevent toxicity to aquatic life.

NR 811.855 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: r. and recr. Register January 2024 No. 817, eff. 2-1-24.

NR 811.856 NR 811.856 Water treatment plant wastewater radionuclide content compliance with the unity equation. Water treatment plant wastewater containing radium or uranium shall not be discharged to a sanitary sewer or to waters of the state unless all of the following requirements are met:

NR 811.856(1) (1) Unity equation. The levels of radium and uranium in the wastewater shall meet the limits of the Unity Equation as calculated based upon the requirements of the department of health services under s. DHS 157.30 (3) and Appendix E of ch. DHS 157.

NR 811.856(2) (2) Calculations.

NR 811.856(2)(a) (a) Unity equation calculations in accordance with sub. (1) shall be performed for water treatment plants treating wells with combined radium-226 and radium-228, uranium, or both, exceeding the maximum contaminant level. The department may require unity equation calculations on a case-by-case basis if other radionuclides may be of concern.

NR 811.856(2)(b) (b) The water system owner or its consultant shall submit the Unity Equation assumptions and calculations to the department for review and approval before, or along with, the submission of plans and specifications to the department for the radionuclide removal water treatment equipment or plant.

NR 811.856(3) (3) Corrective actions. Corrective action as approved by the department shall be taken, if necessary, to maintain the result of the Unity Equation calculations as less than one.

NR 811.856 Note Note: The department’s Public Water Supply Section located in Madison may be contacted to obtain a copy of DNR Application of DHS Radionuclide Wastewater Disposal Criteria for help in addressing Unity Equation issues.

NR 811.856 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; correction in (1) made under s. 13.92 (4) (b) 7., Stats., Register November 2010 No. 659; CR 22-074: r. and recr. (intro.), am. (2) (a) Register January 2024 No. 817, eff. 2-1-24.

NR 811.857 NR 811.857 Backwash wastewater from lime softening water treatment plants. Filter backwash wastewater from lime softening water treatment plants shall be disposed of by any of the following methods:

NR 811.857(1) (1) Recycle. Returned to the inlet end of the plant in accordance with the requirements of s. NR 811.862.

NR 811.857(2) (2) Discharge to a sanitary sewer. Lime softening backwash water may be discharged to a sanitary sewer system subject to the requirements under s. NR 811.85 (1) (a).

NR 811.857(3) (3) Discharge to a water of the state. Backwash wastewater from lime softening treatment plants may be discharged to a water of the state subject to the requirements under s. NR 811.85 (1) (b). Suspended solids shall be removed from the filter backwash wastewater prior to discharge by means of settling, and possibly coagulation. The pH shall be adjusted to within the range of 6.0 and 9.0 prior to surface water discharge.

NR 811.857 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: cr. (1) (title), am. (2), (3) Register January 2024 No. 817, eff. 2-1-24.

NR 811.858 NR 811.858 Lime softening sludge. Sludge from plants using lime to soften water will vary in quantity and in chemical characteristics depending on the softening process and the chemical characteristics of the water being softened. The department shall impose additional disposal requirements on a case-by-case basis for sludge from plants treating water containing radium-226, radium-228, uranium, or other radionuclides. These additional requirements shall modify the requirements for specific disposal methods. The requirements for specific disposal methods are as follows:

NR 811.858(1) (1) Lagoons. The design shall meet the following minimum requirements:

NR 811.858(1)(a) (a) Locations free from flooding, with grading or ditching to divert surface runoff.

NR 811.858(1)(b) (b) Minimum lagoon depth of 5 feet with interior and exterior slopes of 3:1.

NR 811.858(1)(c) (c) Two years solids storage volume for temporary lagoons and 8- to 10-years storage volume for permanent lagoons.

NR 811.858(1)(d) (d) A minimum of 2 cells to provide flexibility in operation. The inlet and outlet structures shall be designed so that the cells may be operated independently.

NR 811.858(1)(e) (e) Adjustable decanting devices.

NR 811.858(1)(f) (f) Means of convenient cleaning.

NR 811.858(1)(g) (g) Lagoons shall be designed to comply with ch. NR 213.

NR 811.858(1)(h) (h) Supernatant from lagoon thickening shall be discharged to a sanitary sewer, water of the state, or holding tank, under the applicable requirements of s. NR 811.85 (1). Lime softening sludge supernatant that is discharged to a water of the state shall meet the treatment requirements under s. NR 811.857 (3).

NR 811.858(2) (2) Application to agricultural land. The department may allow liquid sludge to be applied to agricultural land by tank truck. This method requires proper handling facilities, vehicles, and equipment to allow hauling and spreading that does not create dust, odors, or other nuisance conditions. Adequate sludge holding facilities are required for use during times that trucks cannot operate. Land application of sludge, including the radionuclide content, shall comply with s. NR 811.85 (1) (b).

NR 811.858 Note Note: Under s. NR 214.02 (3) (k), uncontaminated lime sludges from water supply treatment facilities shall follow the land spreading requirements under s. NR 518.04 (3). Uncontaminated lime sludges exclude any sludges containing radionuclide content that are regulated under a WPDES permit under ch. 283, Stats. The department’s wastewater program in the bureau of water quality is responsible for the issuance of WPDES permits for discharges from waterworks to a water of the state. Waterworks owners should contact the department’s district wastewater staff for WPDES permit application and compliance requirements.

NR 811.858(3) (3) Discharge to sanitary sewer. Discharge to sanitary sewer may be approved on a case-by-case basis if a study or experience has shown that problems will not occur in the sewage collection system or at the wastewater treatment plant. The discharge of lime softening sludge shall meet the requirements under s. NR 811.85 (1) (a). A water system owner shall submit plans to both the department’s wastewater section and public water engineering section for a new discharge or an increase in volume or percent solids of lime softening sludge to sanitary sewer for review and approval prior to initiation of the construction or operational change.

NR 811.858(4) (4) Mechanical dewatering. Mechanical dewatering may be utilized if approved by the department after review of the results of pilot testing. Supernatant from mechanical dewatering shall be discharged to a sanitary sewer, water of the state, or holding tank, pursuant to the applicable requirements under s. NR 811.85 (1). Effluent that is discharged to a surface water shall also meet the treatment requirements under s. NR 811.857 (3).

NR 811.858 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (intro.), (1) (b), (d), (f), cr. (1) (g), (h), am. (2), (3), r. and recr. (4) Register January 2024 No. 817, eff. 2-1-24.

NR 811.859 NR 811.859 Spent media.

NR 811.859(1) (1) General. The department may require special handling and disposal for spent media from water treatment plants under any of the following circumstances:

NR 811.859(1)(a) (a) Granular activated carbon shall be evaluated when treating water with volatile organic compounds, radium, uranium, or radon gas.

NR 811.859(1)(b) (b) Filter sand, green sand, ion exchange media, membranes, support media, and other media that may retain radionuclide material shall be evaluated when treating water with radium-226, radium-228, or uranium.

NR 811.859(2) (2) Disposal approval. The water system owner shall contact the department for approval prior to disposal of the medias listed under sub. (1). The water system owner shall submit a written request indicating the type of media, the volume of media, the contaminants of concern and their concentration in the influent water and the media, the proposed method of transportation, and the proposed method of disposal. A landfill that accepts spent media from a water treatment facility that treated groundwater containing radium shall comply with the requirements under s. NR 506.12 prior to accepting the spent media waste for disposal.

NR 811.859 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (1) (intro.), (a), (2) Register January 2024 No. 817, eff. 2-1-24.

NR 811.860 NR 811.860 Backwash wastewater from surface water treatment plants. Filter backwash wastewater from surface water treatment plants shall be disposed of by any of the following methods:

NR 811.860(1) (1) Recycling. Filter backwash wastewater may be returned to the inlet end of the plant in accordance with the requirements under s. NR 811.862. Membrane filtration plants may not recycle backwash wastewater unless the waste goes through coagulation and settling processes prior to being applied to the membranes. Membrane manufacturers may have specific feed water quality parameter requirements that could limit recycling. Chemical cleaning waste from membrane plants may not be recycled unless specifically approved by the department. A plant recycling filter wastewater shall have an alternative means of disposing of wastewater available during periods when raw water quality precludes the ability to recycle all or some of the backwash water.

NR 811.860(2) (2) Discharge to sanitary sewer. Backwash water may be discharged to a sanitary sewer system subject to the requirements under s. NR 811.85 (1) (a).

NR 811.860(3) (3) Discharge to surface water. Backwash wastewater from filtration for surface water treatment may be discharged to a surface water of the state subject to the requirements under s. NR 811.85 (1) (b) and all of the following requirements:

NR 811.860(3)(a) (a) Suspended solids shall be removed from the filter backwash wastewater prior to surface water discharge. This will require settling and may require coagulation as determined by the department on a case-by-case basis. Additional treatment may be necessary to meet the requirements of the WPDES permit.

NR 811.860(3)(b) (b) The solids removed during treatment of backwash water shall be land spread or discharged to a holding tank in accordance with the requirements under s. NR 811.85 (1) (b) and (c).

NR 811.860(3)(c) (c) Chemical cleaning waste from membrane plants may not be discharged to surface water.

NR 811.860(4) (4) Treated by secondary membrane. The filter backwash water may be treated by a dedicated membrane system and sent to the clearwell if approved by the department in accordance with all of the following requirements:

NR 811.860(4)(a) (a) The membrane, as can be demonstrated by integrity testing conducted every 8 hours, shall provide a minimum 99.9997 percent (5.5-log) removal of Cryptosporidium.

NR 811.860(4)(b) (b) If the membrane cannot be demonstrated to provide a 99.9997 percent (5.5-log) removal of Cryptosporidium, UV shall be provided following the membrane. The membrane and UV together shall provide a minimum of 99.9997 percent (5.5-logs) of removal or inactivation of Cryptosporidium, or a combination of both.

NR 811.860(4)(c) (c) A target removal of less than 99.9997 percent (5.5-logs) of Cryptosporidium may be considered by the department if testing of the backwash water in accordance with s. NR 809.334 and bin classification in accordance with s. NR 810.34 would result in a bin classification less than Bin 4.

NR 811.860 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (1), r. and recr. (2), (3) Register January 2024 No. 817, eff. 2-1-24.

NR 811.861 NR 811.861 Alum or other coagulant sludge. Alum or other coagulant sludge shall be disposed of by the following methods:

NR 811.861(1) (1) Lagoons. The general design criteria for lagoons are under s. NR 811.858 (1). The lagoon effluent shall be discharged to a sanitary sewer, water of the state, or holding tank and shall meet the provisions under s. NR 811.85 (1).

NR 811.861(2) (2) Discharge to sanitary sewers. The department may approve the discharge of coagulant sludge to sanitary sewers on a case-by-case basis if a study or experience has shown that problems will not occur in the sewage collection system or at the sewage treatment plant. The discharge of coagulant sludge shall meet the requirements under s. NR 811.85 (1) (a). The water system owner shall submit plans for a new discharge or an increase in volume or percent solids of coagulant sludge to sanitary sewer to the department for review and approval prior to initiation of the construction or operational change.

NR 811.861 Note Note: Plans for water treatment plants with wastewater discharges should be submitted to both the department’s wastewater section and public water engineering section.

NR 811.861(3) (3) Mechanical dewatering. Mechanical dewatering may be utilized if approved by the department after review of the results of testing.

NR 811.861(4) (4) Supernatant water. Any thickener supernatant or liquids from dewatering processes to be recycled shall meet the requirements of s. NR 811.862.

NR 811.861 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (1), (2), (4) (title) Register January 2024 No. 817, eff. 2-1-24.

NR 811.862 NR 811.862 Recycling backwash wastewater. Filter and contactor backwash wastewater may be recycled if approved by the department in accordance with all of the following requirements:

NR 811.862(1) (1) The filter and contactor backwash wastewater shall be settled in a settling tank or equalization basin prior to being returned to the inlet end of the plant. For surface water systems, a coagulant or polymer may be required to enhance settling to prevent protozoans such as Giardia lamblia and Cryptosporidium from concentrating. Tanks and basins shall meet all of the following minimum requirements:

NR 811.862(1)(a) (a) The tanks shall contain the anticipated volume of backwash wastewater produced by the plant when operating at design capacity.

NR 811.862(1)(b) (b) To provide operational flexibility, the tanks shall be of adequate size to contain the total waste washwater from 2 consecutive backwashes, subject to the design backwash operations.

NR 811.862(2) (2) The settled filtered backwash wastewater shall be returned to the head end of the plant at a maximum rate of 10% of the instantaneous flow rate at which raw water is entering the plant. All of the following requirements shall be met:

NR 811.862(2)(a) (a) The point of recycle shall be prior to all treatment and chemical addition except chemical treatment for zebra mussel control at the intake.

NR 811.862(2)(b) (b) A meter shall be provided on the recycle line.

NR 811.862(2)(c) (c) A means shall be provided for controlling the rate at which the settled backwash wastewater is returned.

NR 811.862(3) (3) For systems treating groundwater, the settled filtered backwash wastewater shall be disinfected prior to or at the time that it is returned to the head end of the plant.

NR 811.862(4) (4) Reservoirs to be used to settle backwash wastewater for plants treating potable groundwater shall be constructed to potable reservoir construction standards as required by subch. IX. The discharge of any wastewater or sludge, or both, from such a reservoir to a sanitary or storm sewer main, manhole, or other collection structure, whether by pump or by gravity, shall not be made through a direct connection. The discharge piping shall terminate downward with a one-foot free air break over the receiving structure as required in s. NR 811.64 (4).

NR 811.862(5) (5) For surface water systems that recycle their backwash wastewater, all of the following reporting and record keeping requirements apply:

NR 811.862(5)(a) (a) A current plant schematic showing the origin of all recycle streams, how any recycle streams are transported, and where the recycle streams enter the treatment process shall be maintained on file with the department.

NR 811.862(5)(b) (b) Information on the typical recycle flow rate, the highest observed plant flow rate each year, and the design flow rate of the plant shall be available to the department upon request.

NR 811.862(5)(c) (c) The information in pars. (a) and (b) along with all of the following information shall be maintained on file for a minimum of 10 years: dates when recycle flow rate has exceeded 10 percent of raw water flow rate entering the plant; how recycle flow rate is controlled; dimension and volume of backwash equalization basin; typical detention time in equalization basin; type of coagulant fed prior to equalization basin; and means of sludge removal from the equalization basin.

NR 811.862 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (1) (b) Register January 2024 No. 187, eff. 2-1-24.

subch. XIII of ch. NR 811 Subchapter XIII — Aquifer Storage Recovery

NR 811.87 NR 811.87 General.

NR 811.87(1) (1) Approval of the department is required prior to the construction of any aquifer storage recovery well or the conversion of any previously constructed well for use as an aquifer storage recovery well.

NR 811.87 Note Note: Approval to construct or develop an aquifer storage recovery well is not an approval to operate an ASR system.

NR 811.87(2) (2) Approval of the department is required prior to the operation of any aquifer storage recovery system.

NR 811.87 Note Note: The department will not issue an approval to operate an ASR system until after it has reviewed and evaluated the results of an approved ASR pilot study.

NR 811.87(3) (3) Only treated drinking water may be placed underground through an ASR system well.

NR 811.87(4) (4) Only a municipal water system may construct an aquifer storage recovery well or operate an ASR system.

NR 811.87(5) (5) The displacement zone around an ASR well may extend no further than 1,200 feet from that ASR well.

NR 811.87 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 811.88 NR 811.88 ASR well performance requirements.

NR 811.88(1) (1) Unless the department determines that it is not technically or economically feasible, the quality of the treated drinking water to be placed underground through an aquifer storage recovery well shall comply with the preventive action limits contained in ch. NR 140 prior to underground injection. In all cases, the quality of the treated drinking water to be placed underground through an aquifer storage recovery well shall meet the primary drinking water standards contained in ch. NR 809 and may not contain any substance at a concentration that exceeds a state or federal health advisory prior to underground injection.

NR 811.88 Note Note: Pursuant to s. 160.19 (2) (b), Stats., the department finds that treated drinking water in a municipal water system may at times exceed preventive action limits established for iron, manganese, nitrate, nitrite, copper, lead, fluoride, asbestos, chloroform, bromoform, bromodichloromethane, and dibromochloromethane. Such exceedances may occur at the point of underground injection and within the displacement zone surrounding an aquifer storage recovery well even though the treated water being injected would remain in compliance with federal and state water quality standards for drinking water. The maximum allowable concentration of a primary drinking water contaminant in treated drinking water has been set by the United States Environmental Protection Agency at the lowest level that is considered to be technically and economically achievable at this time. The department also finds that it is not technically or economically feasible to require that residual concentrations of chloroform, bromoform, bromodichloromethane, and dibromochloromethane be removed from the injected water when a disinfection residual is desired at the wellhead to provide additional protection to the water system from potential biological contamination.

NR 811.88(2) (2) All water that is retrieved through an aquifer storage recovery well shall comply with the primary drinking water standards contained in ch. NR 809 and shall be treated to provide a disinfectant residual prior to recovery into any municipal water distribution system.