Chapter NR 811

NR 811.54(10)(a) (a) The maximum allowable ozone concentration in the air to which workers may be exposed may not exceed 0.1 ppm by volume.

NR 811.54(10)(b) (b) Noise levels resulting from the operation of the ozonation system shall be controlled to within acceptable limits by special room construction and equipment isolation.

NR 811.54(10)(c) (c) High voltage and high frequency electrical equipment shall meet current electrical and fire codes.

NR 811.54(10)(d) (d) An exhaust fan shall be provided in the ozone generation and contactor rooms to remove ozone gas if a leak occurs and shall meet all of the following requirements:

NR 811.54(10)(d)1. 1. One complete air change per minute shall be provided when the room is occupied.

NR 811.54(10)(d)2. 2. The exhaust fan suction shall be located near the floor with the point of discharge located to avoid contamination of air inlets to other rooms and structures, to outside breathable air, or being blocked by snow or other obstructions.

NR 811.54(10)(d)3. 3. Air inlets shall be located near the ceiling and controlled to prevent adverse temperature variations.

NR 811.54(10)(d)4. 4. An exhaust fan switch shall be located outside of the entrance to the room with a signal light indicating fan operation when the fan can be controlled from more than one point.

NR 811.54(10)(e) (e) A portable purge air blower that will remove residual ozone in the contactor prior to entry for repair or maintenance shall be provided.

NR 811.54(10)(f) (f) A sign shall be posted indicating “No smoking, oxygen in use” at all entrances to the treatment plant. In addition, no flammable or combustible materials shall be stored within the oxygen generator areas.

NR 811.54 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (2) (d) 2. Register January 2024 No. 817, eff. 2-1-24.

NR 811.55 NR 811.55 Radionuclide removal.

NR 811.55(1) (1) Radium removal. Water treatment to remove radium shall meet the following requirements:

NR 811.55(1)(a) (a) General. Radium may be removed by using the water treatment processes of zeolite softening, lime-soda softening, reverse osmosis, hydrous manganese oxides, and adsorptive resins. Other processes may also be used to remove radium as approved by the department on a case-by-case basis. The process design shall address the fate of radium in the treatment process including waste disposal. Where applicable, disposal of treatment plant wastes containing radium shall normally be to a sanitary sewer or wastewater treatment plant.

NR 811.55 Note Note: It is recommended that measures be taken to protect workers from gamma radiation exposure and radon gas inhalation where applicable.

NR 811.55(1)(b) (b) Finished water quality. Radium removal processes shall be designed to provide a finished water with a radium content as close to 0 picocuries per liter as practical while maintaining a finished water that is not corrosive. The department shall determine allowable plant outlet water quality, including radium concentrations, based on the raw water quality and the treatment process proposed. If corrosive water is produced during the radium removal process, a department approved method of corrosion control shall be provided.

NR 811.55(1)(c) (c) Finished water sampling and reporting. For the radium removal processes listed in par. (a), a minimum of 4 consecutive quarters of finished water sampling for radium shall be required after the plant becomes operational to demonstrate treatment effectiveness. For other proposed radium removal treatment methods, the required radium monitoring program shall be established by the department. The sampling shall be conducted under worst case conditions. Radium analyses shall be performed by a U.S. environmental protection agency approved laboratory. The laboratory shall forward a copy of the radiological analyses to the department in an electronic format. Water hardness monitoring equipment shall be provided to monitor for hardness breakthrough when softening is used for radium removal. Daily water hardness measurements shall be reported on the monthly operating report submitted to the department. Use of hardness monitoring to substitute for radium analyses shall only be allowed if demonstrated effective by simultaneous radium and hardness sampling conducted for one year.

NR 811.55(1)(d) (d) Water softening. Treatment for radium removal using standard water softening processes shall comply with the requirements of s. NR 811.57.

NR 811.55(1)(e) (e) Hydrous manganese oxides. Water treatment using hydrous manganese oxides for radium removal shall meet the following requirements:

NR 811.55(1)(e)1. 1. Each installation shall be individually pilot tested on-site under a department approval unless the pilot testing requirement is waived by the department based upon documentation of successful similar treatment performance at wells with similar water quality.

NR 811.55(1)(e)2. 2. Pre-mixed or on-site mixed hydrous manganese oxide chemicals shall conform to the applicable NSF/ANSI Standard 60 and AWWA standards as required by s. NR 810.09 (1) (c).

NR 811.55(1)(f) (f) Adsorptive resins. Water treatment using adsorptive resins for radium removal that will continuously accumulate radium on the resin shall meet the following requirements.

NR 811.55(1)(f)1. 1. Each installation shall be individually pilot tested on-site under a department approval unless the pilot testing requirement is waived by the department based upon documentation of successful similar treatment performance at wells with similar water quality.

NR 811.55(1)(f)2. 2. The radiation protection section of the department of health services shall be contacted to obtain a radioactive material license to operate pilot and full scale installations prior to constructing or operating the systems.

NR 811.55(1)(g) (g) Other treatment. Other radium removal treatment processes may be approved by the department on a case-by-case basis using information obtained from department approved on-site pilot studies conducted on the water to be treated.

NR 811.55(1)(h) (h) Waste disposal. Disposal of radium removal treatment plant waste shall comply with subch. XII.

NR 811.55(2) (2) Radon gas removal. Water treatment to remove radon gas shall meet the following requirements:

NR 811.55(2)(a) (a) Radon may be removed using aeration or pressurized granular activated carbon filters. The process design shall address the gamma radiation and disposal concerns associated with the use of granular activated carbon filters.

NR 811.55(2)(b) (b) The design of radon removal equipment shall be based on a department approved on-site pilot study conducted on the water to be treated. The department may approve manufactured radon removal equipment without pilot study on a case-by-case basis if adequate treatment effectiveness is demonstrated to the department.

NR 811.55(2)(c) (c) Aerators used for radon removal shall comply with s. NR 811.45.

NR 811.55(2)(d) (d) Radon gas shall be vented to the atmosphere at an elevation and location to prevent elevated radon gas air concentrations in inhabitable areas.

NR 811.55(2)(e) (e) Granular activated carbon filters for radon removal shall comply with s. NR 811.53. Disposal of carbon filters used for radon removal shall comply with s. NR 811.859.

NR 811.55(2)(f) (f) A minimum of 4 consecutive quarters of finished water sampling for radon gas shall be required after the plant becomes operational to demonstrate treatment effectiveness. The sampling shall be conducted under worst case conditions. Radon gas analyses shall be performed by a U.S. environmental protection agency approved laboratory. The laboratory shall forward a copy of the radiological analyses to the department in an electronic format.

NR 811.55(3) (3) Uranium removal. Water treatment to remove uranium shall meet the following requirements:

NR 811.55(3)(a) (a) The designer of any proposed uranium removal equipment shall contact the department prior to the final design of the equipment to allow for department input on design requirements. The design shall be based on information obtained from department approved on-site pilot studies conducted on the water to be treated. The process design shall address the fate of uranium in the treatment process. Disposal of water treatment plant wastes containing uranium shall be in accordance with written department guidance. If applicable, disposal of treatment plant wastes containing uranium shall be to a sanitary sewer or wastewater treatment plant as approved by the department. The discharged water treatment plant wastes and spent media shall be analyzed for radionuclide content as required by the department. The disposal of spent media containing residual radionuclides shall be as approved by the department.

NR 811.55(3)(b) (b) A minimum of 4 consecutive quarters of finished water sampling for uranium shall be required after the plant becomes operational to demonstrate treatment effectiveness. The sampling shall be conducted under worst case conditions. Uranium analyses shall be performed by a U.S. environmental protection agency approved laboratory. The laboratory shall forward a copy of the radiological analyses to the department in an electronic format.

NR 811.55(3)(c) (c) Prior to constructing or operating the systems, the radiation protection section of the department of health services shall be contacted to obtain a radioactive material license to operate pilot and full scale installations when uranium will be concentrated on the resin or media to a level greater than 170 picocuries per gram at any time during use, including just prior to backwashing, regeneration, or disposal.

NR 811.55(3)(d) (d) Disposal of uranium removal treatment plant waste shall comply with subch. XII.

NR 811.55 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: am. (2) (c) Register January 2024 No. 817, eff. 2-1-24.

NR 811.56 NR 811.56 Sequestration.

NR 811.56(1) (1) Sequestration by polyphosphates. Sequestration by polyphosphates is suitable when concentrations of iron, manganese, or a combination of both, are 1.0 mg/1, or less. Polyphosphate treatment may be less effective for sequestering manganese than for iron. The following requirements shall be met:

NR 811.56(1)(a) (a) Where phosphate treatment is used, chlorine residuals shall be maintained in the distribution system. In addition:

NR 811.56(1)(b) (b) Polyphosphates may not be applied ahead of iron and manganese removal treatment. The point of application shall be prior to any aeration or oxidation and as far upstream as practical from the chlorine or other oxidant application.

NR 811.56(1)(c) (c) Chemical feed installations shall conform to the requirements of subch. VI.

NR 811.56(1)(d) (d) Chemicals for new or existing installations shall meet the applicable NSF/ANSI Standard 60 requirements of s. NR 810.09 (1) (c).

NR 811.56(1)(e) (e) Stock phosphate solution shall be kept covered and disinfected by carrying an approximate 10 mg/1 free chlorine residual unless the phosphate is not able to support bacterial growth, has a pH of 2 or less, and has not been diluted.

NR 811.56(1)(g) (g) If polyphosphate sequestration is practiced, appropriate orthophosphate testing equipment shall be provided.

NR 811.56(1)(h) (h) Possible adverse affects on corrosion shall be considered and addressed if necessary when phosphate addition is proposed for iron or manganese sequestering.

NR 811.56(2) (2) Sequestration by sodium silicates. Sodium silicate sequestration of iron and manganese is appropriate only for groundwater supplies prior to air contact. Sodium silicate addition is applicable to waters containing up to 2 mg/l of iron, manganese, or a combination of both. The following requirements shall be met:

NR 811.56(2)(a) (a) On-site pilot tests are required to determine the suitability of sodium silicate for the particular water and the minimum chemical feed rate needed.

NR 811.56(2)(b) (b) Chlorine residuals shall be maintained throughout the distribution system to prevent biological breakdown of the sequestered iron.

NR 811.56(2)(c) (c) Rapid oxidation of the metal ions such as by chlorine or chlorine dioxide shall accompany or closely precede the sodium silicate addition. Injection of sodium silicate more than 15 seconds after oxidation may cause detectable loss of chemical efficiency. Dilution of feed solutions much below 5% silica as SiO2 shall also be avoided for the same reason.

NR 811.56(2)(d) (d) The amount of silicate added shall be limited to 20 mg/l as SiO2. The combined amount of added and naturally occurring silicate may not exceed 60 mg/l as SiO2.

NR 811.56(2)(e) (e) Chemical feed installations shall conform to the requirements of subch. VI.

NR 811.56(2)(f) (f) Sodium silicate may not be applied ahead of iron or manganese removal treatment.

NR 811.56(2)(g) (g) Liquid sodium silicate shall meet the applicable NSF/ANSI Standard 60 requirements of s. NR 810.09 (1) (c).

NR 811.56 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: r. (1) (f) Register January 2024 No. 817, eff. 2-1-24.

NR 811.57 NR 811.57 Softening. The softening process selected shall be based upon the chemical qualities of the raw water, the desired finished water quality, the requirements for disposal of sludge or brine waste, the cost of plant and chemicals, and plant location. The applicability of the process chosen shall be demonstrated and discussed in detail in an engineering report. For very hard water, the sodium levels in cation exchange softened water shall be considered in selecting the treatment process. Following are requirements for specific processes:

NR 811.57(1) (1) Lime-soda process. The applicable design standards for lime-soda softening of groundwater are the same as those for conventional clarification-filtration surface water treatment plants, except that the minimum settling time may be reduced to 2 hours. Where softening is included in the surface water treatment process, the clarification criteria shall govern. In addition:

NR 811.57 Note Note: See s. NR 811.47 for criteria pertaining to softening with solids contact units and s. NR 811.49 for filtration requirements.

NR 811.57(1)(a) (a) Mechanical sludge removal equipment shall be provided in the sedimentation basin.

NR 811.57(1)(b) (b) Determinations shall be made for the carbon dioxide content of the raw water.

NR 811.57 Note Note: When concentrations exceed 10 mg/l, the economics of removal by aeration as opposed to removal with lime should be considered. See s. NR 811.45 for aeration requirements.

NR 811.57(1)(c) (c) Equipment for stabilization of water softened by the lime-soda process is required.

NR 811.57 Note Note: See s. NR 811.58 for stabilization requirements.

NR 811.57(1)(d) (d) Provisions shall be included for proper disposal of softening sludges.

NR 811.57 Note Note: See s. NR 811.858 for design requirements.

NR 811.57(1)(e) (e) The use of excess lime may not be substituted for chlorination or any other approved method of disinfection.

NR 811.57 Note Note: See s. NR 811.48.

NR 811.57(2) (2) Cation exchange process. Iron, manganese or a combination of both in the oxidized state or unoxidized state may cause resin fouling in the ion exchange process. Pretreatment shall be required whenever the content of iron, manganese, or a combination of both is one milligram per liter or more. In specific instances, the department may also require pretreatment when lesser amounts exist. All of the following requirements shall be satisfied unless the department determines sufficient justification for alternative operational parameters is provided by the vessel manufacturer or demonstrated through pilot testing under s. NR 811.44:

NR 811.57(2)(a) (a) The units shall be of pressure or gravity type, of either an upflow or downflow design, using automatic or manual regeneration. Automatic regeneration is suggested for small plants. A manual override shall be provided for all automatic controls.

NR 811.57(2)(b) (b) The design capacity for hardness removal may not exceed 20,000 grains per cubic foot when resin is regenerated with 0.3 pounds of salt per kilograin of hardness removed.

NR 811.57(2)(c) (c) The depth of the exchange material may not be less than 3 feet.

NR 811.57(2)(d) (d) The rate of softening may not exceed 7 gallons per square foot per minute, and the backwash rate shall be 6 to 8 gallons per square foot per minute.

NR 811.57(2)(e) (e) The freeboard design shall be based upon the specific gravity of the media and the direction of water flow.

NR 811.57(2)(f) (f) The bottoms, strainer systems, and support for the exchange materials shall conform to criteria provided for rapid rate gravity filters in s. NR 811.49.

NR 811.57(2)(g) (g) Facilities shall be included for even distribution of the brine over the entire surface of both upflow or downflow units. Backwash, rinse, and air relief discharge pipes shall be installed in such a manner as to prevent back-siphonage.

NR 811.57(2)(h) (h) A bypass shall be provided around softening units to produce a blended water of desirable hardness. Meters shall be installed on the bypass line and on each softener unit. An automatic proportioning or regulating device and shut-off valve shall be provided on the bypass line. The department may require treatment of the bypassed water to obtain acceptable levels of iron or manganese in the finished water.

NR 811.57(2)(i) (i) Waters having 5 units or more of turbidity may not be applied directly to the cation exchange softener. Silica gel materials may not be used for waters having a pH above 8.4 or when iron is present. When the applied water contains a chlorine residual, the cation exchange material shall be a type that is not damaged by residual chlorine. Phenolic resin may not be used.

NR 811.57(2)(j) (j) Brine storage tanks shall conform to the following requirements:

NR 811.57(2)(j)1. 1. The wet storage tank shall be designed to hold at least 1.5 times the volume of salt delivered to permit refill before the tank is completely empty. The volume of both salt and brine storage to be provided depends upon the size of the plant, the proximity and assuredness of the salt source, and the method of delivery.

NR 811.57(2)(j)2. 2. It shall be isolated from possible sources of contamination.

NR 811.57(2)(j)3. 3. It shall be properly covered and equipped with manholes having overlapping watertight covers to prevent entry of surface runoff where applicable.

NR 811.57(2)(j)4. 4. Overflows and vents shall be designed in accordance with s. NR 811.64 (4) and (8), respectively, where applicable.

NR 811.57(2)(j)5. 5. The water for filling the tank shall be distributed over the entire surface of the tank by pipes at least 2 pipe diameters above the maximum liquid level in the tank or be protected from back-siphonage.

NR 811.57(2)(j)6. 6. The underdrain collection system shall be covered with a screen or perforated plate to allow brine but not salt to pass through.

NR 811.57(2)(j)7. 7. A sampling tap shall be provided on the brine discharge line in order that the concentration of brine can be determined. A suitable means for measuring the volume of brine used for regeneration shall be provided.

NR 811.57(2)(j)8. 8. Pipes and contact materials shall be resistant to the aggressiveness of salt. Steel and concrete shall be coated with a non-leaching protective coating that is compatible with salt and brine and is certified by ANSI/NSF standard 61, dated March 15, 2022, which is incorporated by reference.

NR 811.57 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.