Chapter NR 811

NR 811.42 NR 811.42 Treatment of water from surface water sources. Treatment of water from surface water sources shall meet the following requirements:

NR 811.42(1) (1) General requirements. All public water supply systems drawing water from lakes, rivers, streams, or other surface water sources shall, after the water is drawn, treat the water as provided in this chapter. In general and at a minimum, this treatment shall include coagulation, sedimentation, and filtration plus disinfection or membrane filtration plus disinfection. Filtration is required in all cases. Total plant removal and inactivation shall provide a minimum 99.9 percent (3-log) inactivation of Cryptosporidium and Giardia Lamblia plus 99.99 percent (4-log) inactivation of viruses.

NR 811.42(2) (2) Treatment requirements. The following treatment requirements shall be met:

NR 811.42(2)(a) (a) Conventional plants consisting of coagulation, sedimentation, and filtration that meet the turbidity requirements in s. NR 810.29 (1) are granted the following removal credits: 99.7 percent (2.5-log) Giardia Lamblia, 99.9 percent (3.0-log) Cryptosporidium and 99 percent (2-log) virus. The remaining 68 percent (0.5-log) Giardia Lamblia inactivation and 99 percent (2.0-log) virus inactivation shall be provided by CT disinfection. For conventional plants, a minimum of one-half of the required CT shall be provided after filtration.

NR 811.42(2)(b) (b) Log removal credit for membrane filtration shall be site specific as approved by the department.

NR 811.42(2)(c) (c) Additional treatment may be required by the department as provided in s. NR 810.35.

NR 811.42(2)(d) (d) The department may approve any request for a deviation from required treatment methods based on data which shows that the requirements of this chapter are unnecessary in the specific case.

NR 811.42(3) (3) Redundancy. All critical treatment components shall be provided with redundancy.

NR 811.42(4) (4) CT values. CT values for the inactivation of Giardia Lamblia, Cryptosporidium, and viruses can be found in ss. NR 810.47 to 810.62.

NR 811.42(5) (5) Chlorine residual requirements. The free chlorine concentration in the water entering the distribution system shall be at least 0.2 mg/1 at the entry point to the distribution system and detectable throughout the distribution system or the total combined chlorine concentration shall be at least 1.0 mg/l at the entry point to the distribution system and detectable throughout the distribution system. Continuous chlorine residual monitoring of the water entering the distribution system shall be provided as required in ss. NR 809.74 (2) and 810.38 (2) (c).

NR 811.42 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 811.43 NR 811.43 Treatment of water from groundwater sources. Treatment of water from groundwater sources shall meet the following requirements:

NR 811.43(1) (1) Disinfection capability required. All municipal water systems constructed or modified after December 1, 2010, shall have equipment and the necessary appurtenances that can continuously disinfect the water. The department may require the installation of disinfection equipment at existing other-than-municipal water systems if necessary to ensure a safe water supply.

NR 811.43(2) (2) Disinfectant residual requirements. Disinfection of water drawn from groundwater sources is to supplement and not replace proper well location, construction, and source protection. When disinfection of water drawn from a groundwater source is required to maintain bacteriologically safe water, the residual maintained in the distribution system and the residual monitoring is the same as that required for surface water in s. NR 811.42 (5).

NR 811.43(3) (3) Disinfection requirements for wells. Specific disinfection requirements for wells are provided in subch. II. Any additional disinfection requirements for wells will be developed by the department if necessary on a case by case basis.

NR 811.43(4) (4) Disinfection of groundwater exposed to the atmosphere as part of a treatment process. Disinfection of water drawn from groundwater sources is required at facilities that expose the water to the atmosphere, such as open basins, open filters, air stripping towers, or gravity aerators.

NR 811.43(5) (5) Required actions for wells with non-complying water quality. One of the following actions shall be taken after consulting with the department if untreated water drawn from a groundwater source exceeds one or more of the primary maximum contaminant levels in ch. NR 809 or a department health advisory:

NR 811.43(5)(a) (a) The well shall be removed from service and permanently abandoned.

NR 811.43(5)(b) (b) The well shall be removed from service and either reconstructed or provided with permanent treatment to provide complying water quality. Wells may temporarily continue in service without reconstruction or providing permanent treatment only as approved by the department. Department approval is required prior to reconstructing the well or providing water treatment. Under emergency conditions, the department may allow temporary use of a well from which bacteriologically contaminated groundwater is drawn if disinfection adequate to ensure safe water is provided. In such cases, disinfection measures meeting the requirements of sub. (3) shall be provided. A continuous boil water notice may be required by the department during all or part of this interim period if deemed necessary by the department to protect public health.

NR 811.43(6) (6) Groundwater under the direct influence of surface water. The department may allow the use of water drawn from a groundwater source that has been determined by the department to be under the direct influence of surface water provided that treatment facilities meeting the requirements of subch. II of ch. NR 810 are provided as approved by the department. The total plant removal and inactivation shall provide a minimum 3-log inactivation of Cryptosporidium and Giardia Lamblia plus 4-log inactivation of viruses. The disinfectant residual maintained in the distribution system and residual monitoring shall be the same as required for treatment of water drawn from a surface water source in s. NR 811.42 (5). The department may approve modified treatment requirements for other-than-municipal public water systems if surface water treatment is impractical and if sufficient treatment can be provided. The supplier of water shall contact the department to determine what modified treatment will be approved.

NR 811.43(7) (7) Redundancy. All critical treatment components shall be provided with redundancy.

NR 811.43(8) (8) CT values. CT values for the inactivation of Giardia Lamblia, Cryptosporidium, and viruses can be found in ss. NR 810.47 to 810.62.

NR 811.43(9) (9) Treatment for nitrate. If the source water quality exceeds the nitrate maximum contaminant level set under s. NR 809.11 and treatment, blending, or other department-approved methods are provided to reduce the entry point nitrate concentration beneath the maximum contaminant level, a continuous nitrate analyzer shall be provided at the entry point. The continuous nitrate analyzer shall be programmed to include shut off controls or alarms if the nitrate concentration at the entry point exceeds the maximum contaminant level.

NR 811.43 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (1), (4), cr. (9) Register January 2024 No. 817, eff. 2-1-24.

NR 811.44 NR 811.44 Pilot testing. Pilot testing is required to establish effective treatment and operation requirements for new treatment methods, if revisions are proposed to existing treatment methods, if the water quality poses significant treatment issues, and if design parameters need to be determined for the first time or for the specific site conditions. The department may waive the pilot testing requirement if information on other locations where the proposed treatment methods using similar water quality are already in place and operating successfully is available or if other justification necessary to support the proposed treatment processes is submitted to the department. Pilot testing shall address the following requirements:

NR 811.44(1) (1) Plans, specifications, and an engineering report detailing the proposed pilot plant design, operation, sampling, lab analyses, and any waste disposal shall be submitted to the department and the written approval of the department shall be obtained prior to constructing or operating the pilot plant. At minimum, the pilot plant proposal shall address the following issues, where they apply:

NR 811.44(1)(a) (a) Pilot plant treatment design including all operating parameters.

NR 811.44(1)(b) (b) Length of pilot plant operation. The pilot plant shall operate long enough to establish the treatment effectiveness, media run lengths, wastewater volumes and characteristics, and any other necessary operating parameters. The pilot plant shall operate through a minimum of 2 treatment cycles or as determined by the department.

NR 811.44(1)(c) (c) Chemicals and chemical feed equipment to be used along with chemical addition rates.

NR 811.44(1)(d) (d) Waste disposal.

NR 811.44(1)(e) (e) Operator safety.

NR 811.44(1)(f) (f) Backflow or back-siphon protection for any water system facilities that the pilot plant may be connected to.

NR 811.44(1)(g) (g) Pilot plant security.

NR 811.44(1)(h) (h) Justification for pilot plant design and operation that does not meet the requirements of the applicable sections of subch. VII.

NR 811.44(2) (2) A report summarizing the results of the pilot plant testing and making recommendations for any full scale water system improvements shall be submitted to the department for review and comment by the owner or the owner’s representative prior to or along with the submittal of plans and specifications for any permanent installations.

NR 811.44 Note Note: The department recommends the submittal of pilot plant results reports prior to submittal of final plans and specifications for treatment vessels.

NR 811.44 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: cr. (1) (h) Register January 2024 No. 817, eff. 2-1-24.

NR 811.45 NR 811.45 Aeration. Aeration treatment devices described in this section may be used for oxidation, separation of gases, or for taste and odor control. Air stripping towers shall meet the requirements of s. NR 811.53 (2), which can be used for the removal or reduction of some volatile organic compounds. The following requirements shall be met:

NR 811.45(1) (1) Natural draft aeration. The design for natural draft aeration shall provide that:

NR 811.45(1)(a) (a) Water is distributed uniformly over the top tray.

NR 811.45(1)(b) (b) Water is discharged through a series of 3 or more trays with separation of trays not less than 6 inches.

NR 811.45(1)(c) (c) Trays are loaded at a rate of one to 5 gallons per minute for each square foot of total tray area.

NR 811.45(1)(d) (d) Trays have slotted, heavy woven wire mesh with 0.5-inch openings or perforated bottoms.

NR 811.45(1)(e) (e) Perforations are 3/16 to 1/2 inches in diameter, spaced one to 3 inches on center, when perforations are used.

NR 811.45(1)(f) (f) Construction is of durable material resistant to the aggressiveness of the water and dissolved gasses.

NR 811.45(1)(g) (g) Contamination from sources such as those listed is sub. (7) is minimized by providing down-turned, louvered or hooded, screened air inlet or outlet openings. Screens shall be constructed of 24-mesh corrosion resistant material.

NR 811.45(1)(h) (h) Exhaust air is discharged directly to the outside atmosphere and in a location that will be protective of public health.

NR 811.45(2) (2) Forced or induced draft aeration. The design for forced or induced draft aeration shall provide that:

NR 811.45(2)(a) (a) Water is distributed uniformly over the top tray.

NR 811.45(2)(b) (b) The blower and blower motor are weatherproof and are installed in a weather-tight, screened enclosure.

NR 811.45(2)(c) (c) There is an adequate countercurrent flow of air through the enclosed aeration column.

NR 811.45(2)(d) (d) Aerator trays are loaded at a rate of one to 5 gallons per minute for each square foot of total tray area.

NR 811.45(2)(e) (e) Water will discharge through a series of 5 or more trays with separation of trays not less than 6 inches or as approved by the department.

NR 811.45(2)(f) (f) Construction is of durable material resistant to the aggressiveness of the water and dissolved gasses.

NR 811.45(2)(g) (g) The aerator is insect-proof, watertight, and light-proof.

NR 811.45(2)(h) (h) The air intake is located above grade and the air introduced into the column is as free as possible from contamination sources such as those listed in sub. (7).

NR 811.45(2)(i) (i) The water outlet is adequately sealed to prevent unwanted loss of air.

NR 811.45(2)(j) (j) Interior and exterior sections of the aerator can be easily reached or removed for maintenance.

NR 811.45(2)(k) (k) The air inlet to the blower and the tower discharge vent shall meet all of the following requirements:

NR 811.45(2)(k)1. 1. Be screened.

NR 811.45(2)(k)2. 2. Be provided with a downturned, hooded, or mushroom cap that protects the screen from the entrance of extraneous matter including insects and birds, obnoxious fumes, all types of precipitation and condensation, and windborne debris or dust.

NR 811.45(2)(k)3. 3. Be constructed of 24-mesh corrosion resistant material and installed at a location least susceptible to vandalism or damage.

NR 811.45(2)(k)4. 4. Contain an air inlet that is provided with a dust filter.

NR 811.45(2)(L) (L) Exhaust air is discharged directly to the outside atmosphere and in a location that will be protective of public health.

NR 811.45(3) (3) Pressure aeration. Pressure aeration installations shall meet the following requirements:

NR 811.45(3)(a) (a) Pressure aeration may be used for oxidation purposes. Pressure aeration will not be approved for removal of dissolved gases.

NR 811.45(3)(b) (b) Filters following pressure aeration shall be provided with adequate exhaust devices for release of air.

NR 811.45(3)(c) (c) Pressure aeration devices shall be designed to cause a thorough mixing of compressed air with the water being treated.

NR 811.45(3)(d) (d) Pressure aeration devices shall provide screened and filtered air that is free of obnoxious fumes, dust, dirt, and other contaminants.

NR 811.45(3)(e) (e) Air compressors supplying pressure aerators shall be oil-less.

NR 811.45(3m) (3m) Packed tower aeration. Packed tower aeration systems shall meet all of the following requirements:

NR 811.45(3m)(a) (a) Materials of construction shall meet all of the following requirements:

NR 811.45(3m)(a)1. 1. The packing material shall be certified by ANSI/NSF standard 61 dated March 15, 2022, which is incorporated by reference.

NR 811.45 Note Note: A copy of ANSI/NSF standard 61 dated March 15, 2022 is available for inspection at the Legislative Reference Bureau and may be obtained for personal use from NSF International, https://www.nsf.org.

NR 811.45(3m)(a)2. 2. The tower shall be constructed of stainless steel, concrete, or aluminum.

NR 811.45(3m)(b) (b) Process design shall meet all of the following requirements:

NR 811.45(3m)(b)1. 1. Water loading rates shall be in the range from 15 to 30 gallons per minute per square foot. Water loading rates outside of this range may be used if justified to the department by pilot testing under s. NR 811.44.

NR 811.45(3m)(b)2. 2. The ratio of the packing height to column diameter shall be at least 7:1 for the pilot unit and at least 10:1 for the full-scale tower. The type and size of the packing used in the full-scale unit shall be the same as that used in the pilot study.

NR 811.45(3m)(b)3. 3. The minimum volumetric air to water ratio at peak water flow shall be 25:1 and the maximum shall be 80:1. Air to water ratios outside of these ranges may be justified to the department by pilot testing under s. NR 811.44.

NR 811.45(3m)(c) (c) The water flow system shall meet all of the following requirements:

NR 811.45(3m)(c)1. 1. Water shall be distributed uniformly at the top of the tower using spray nozzles or orifice-type distributer trays that prevent short circuiting.

NR 811.45(3m)(c)2. 2. A mist eliminator shall be provided above the water distributor system.

NR 811.45(3m)(c)3. 3. A side wiper redistribution ring shall be provided at least every 10 feet in order to prevent water channeling along the tower wall and short circuiting.

NR 811.45(3m)(c)4. 4. Smooth-end sample faucets shall be provided on the influent and effluent piping.

NR 811.45(3m)(c)5. 5. The effluent sump shall have easy access for inspection and cleaning.

NR 811.45(3m)(c)6. 6. A pump to waste line shall be provided in the effluent piping to allow for discharge of water and chemicals used to clean the tower.

NR 811.45(3m)(c)7. 7. The design shall prevent freezing of the influent riser and effluent piping when the unit is not operating. If piping is buried, it shall be maintained under positive pressure higher than the ground surface.

NR 811.45(3m)(c)8. 8. The water flow to each tower shall be metered.

NR 811.45(3m)(c)9. 9. Include an overflow line that discharges 12 to 24 inches above a splash pad or drainage inlet. Proper drainage shall be provided to prevent flooding of the area.