Chapter NR 811

NR 811.575 Note Note: The department recommends automatic regeneration for small municipal water systems.

NR 811.575(2) (2) Treatment systems designed for the removal of acute contaminants may not include a bypass for the anion exchange units. When an anion exchange unit is bypassed, a totalizing meter and a proportioning or regulating device or flow regulating valves shall be installed on the bypass line.

NR 811.575(3) (3) The design capacity of the regeneration process shall be in accordance with the specifications of the resin manufacturer. For nitrate removal, the design capacity shall not exceed 10,000 grains per cubic foot when the resin is regenerated at 15 pounds of salt per cubic foot of resin.

NR 811.575(4) (4) A water system treating for acute contaminants shall use at least 2 anion exchange units. The treatment capacity of each unit shall be capable of producing the maximum day water demand at a level below the maximum contaminant level for the contaminant of concern.

NR 811.575(5) (5) The anion exchange resin shall have high selectivity for the contaminant of concern.

NR 811.575(6) (6) Flow rates through the anion exchange units shall be justified through pilot testing under s. NR 811.44 or by appropriate justification by the resin manufacturer.

NR 811.575(7) (7) The freeboard design of the anion exchange unit shall be based upon the specific gravity of the media and the direction of water flow.

NR 811.575(8) (8) The bottoms, strainer systems, and support for anion exchange materials shall conform to requirements for rapid rate gravity filters under s. NR 811.49 (1).

NR 811.575(9) (9) Brine storage tanks shall conform to all of the following requirements:

NR 811.575(9)(a) (a) Each 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 811.575(9)(b) (b) Each tank shall be isolated from possible sources of contamination.

NR 811.575(9)(c) (c) Each tank shall be properly covered and equipped with manholes having overlapping watertight covers to prevent entry of surface runoff, where applicable. If the brine tanks are located outside of the pumphouse, the access manways shall meet the design requirements under s. NR 811.64 (7) (a).

NR 811.575(9)(d) (d) Each tank shall contain overflows and vents that are designed in accordance with s. NR 811.64 (4) and (8), when applicable.

NR 811.575(9)(e) (e) 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 811.575(9)(f) (f) The underdrain collection system shall be covered with a screen or perforated plate to allow brine but not salt to pass through.

NR 811.575(9)(g) (g) The brine discharge line shall have a sampling tap so that the concentration of brine may be determined. A suitable means for measuring the volume of brine used for regeneration shall be provided.

NR 811.575(9)(h) (h) Pipes and contact materials shall be resistant to the aggressiveness of salt. Steel and concrete shall be coated with an ANSI/NSF standard 61 certified, non-leaching protective coating that is compatible with salt and brine.

NR 811.575 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 811.575(9)(i) (i) Bagged salt and dry bulk salt storage shall be enclosed and separated from other operating areas to prevent damage to equipment.

NR 811.575(10) (10) Brine wastes shall meet the requirements under s. NR 811.854.

NR 811.575(11) (11) Smooth-end sampling taps shall be provided for control purposes. Taps shall be located on each raw water source, each treatment unit influent and each treatment unit effluent. Testing equipment shall be provided to adequately control the treatment process at all plants.

NR 811.575(12) (12) Water from ion exchange treatment plants shall be stabilized as required under s. NR 811.58 (4), except when the department determines that the treated water will be non-corrosive.

NR 811.575(13) (13) Prior to start-up of the equipment, the resin shall be regenerated with no less than 2 bed volumes of water containing sodium chloride, or other appropriate regenerant followed by an adequate rinse.

NR 811.575(14) (14) Appropriate test equipment for the target contaminant shall be provided to determine treatment effectiveness.

NR 811.575 History History: CR 22-074: cr. Register January 2024 No. 817, eff. 2-1-24.

NR 811.58 NR 811.58 Stabilization. Water that is unstable to the extent of causing corrosion or deposition problems in the distribution system, whether a result of natural causes or water treatment processes, shall be stabilized. The following standards shall apply:

NR 811.58(1) (1) Carbon dioxide addition.

NR 811.58(1)(a) (a) Recarbonation chamber design shall provide:

NR 811.58(1)(a)1. 1. A total detention time of 20 minutes or as approved by the department.

NR 811.58(1)(a)2. 2. Two compartments, with a depth that will provide a diffuser submergence not less than 7.5 feet nor greater than recommended by the manufacturer and as follows:

NR 811.58(1)(a)2.a. a. A mixing compartment having a detention time of at least 3 minutes.

NR 811.58(1)(a)2.b. b. A reaction compartment.

NR 811.58(1)(b) (b) The design shall prevent carbon dioxide from entering the plant from the recarbonation and reaction chamber.

NR 811.58(1)(c) (c) Plants generating carbon dioxide from combustion shall have open top recarbonation tanks in order to dissipate carbon monoxide gas.

NR 811.58(1)(d) (d) Provisions shall be made for draining the recarbonation basin and removing sludge.

NR 811.58(2) (2) Phosphates. Phosphates may be used for sequestering calcium in lime softened water, corrosion control and in conjunction with alkali feed following ion exchange softening. When used:

NR 811.58(2)(a) (a) Feed equipment shall conform to requirements in ss. NR 811.38 to 811.40.

NR 811.58(2)(b) (b) Phosphate chemicals shall meet the NSF/ANSI Standard 60 requirements.

NR 811.58(2)(c) (c) Stock phosphate solution shall be kept covered and disinfected by carrying an approximate 10 mg/1 chlorine residual. The department may exempt phosphate solutions having a pH of 2.0 or less from this requirement.

NR 811.58(2)(d) (d) Facilities shall be designed to maintain satisfactory chlorine residuals as indicated in s. NR 810.09 (2) and (3).

NR 811.58(2)(e) (e) The total phosphate applied may not exceed 10 mg/1 as PO4.

NR 811.58(3) (3) Split treatment. If approved by the department, a lime-soda water treatment plant may be designed using ‘split treatment’ in which raw water is blended with lime-treated water to partially stabilize the water. Treatment plants designed to utilize ‘split treatment’ shall contain facilities for further stabilization by other methods.

NR 811.58(4) (4) Alkali feed. An alkali feeder shall be provided for all ion exchange water softening plants to provide stable water unless the effluent water is shown to be non-corrosive. Other waters may also be corrosive and require pH adjustment. The chemical shall be adequately mixed and the point of application located such that any deposition in the piping is minimized. The piping shall be accessible for cleaning or replacement. Equipment for monitoring pH shall be provided.

NR 811.58(5) (5) Carbon dioxide reduction by aeration. The carbon dioxide content of an aggressive water may be reduced by aeration. Aeration devices shall conform to s. NR 811.45.

NR 811.58(6) (6) Other treatment. Other treatment for controlling corrosive waters by the use of sodium silicate and sodium bicarbonate may be used where necessary. Any proprietary compound shall receive the specific approval of the department before use. Chemical feeders shall comply with the requirements in subch. VI.

NR 811.58(7) (7) Control. Laboratory equipment shall be provided for determining the effectiveness of stabilization treatment.

NR 811.58 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10; CR 22-074: r. (1) (e) Register January 2024 No. 817, eff. 2-1-24.

NR 811.59 NR 811.59 Taste and odor control. Waterworks which are designed and constructed to provide taste and odor control shall comply with any requirements provided for the following applicable methods:

NR 811.59(1) (1) Chlorination. Chlorination is effective for the removal of some objectionable odors. Adequate concentration and contact time shall be provided to complete the chemical reactions involved. Excessive potential trihalomethane or other disinfection by-product production through this process shall be investigated by bench-scale testing prior to design.

NR 811.59(2) (2) Chlorine dioxide. Chlorine dioxide may be used in the treatment of any taste or odor which is treatable by an oxidizing compound. Provision shall be made for proper storage and handling of sodium chlorite to eliminate any danger of explosion.

NR 811.59(3) (3) Powdered activated carbon.

NR 811.59(3)(a) (a) Powdered activated carbon may be added prior to coagulation to provide maximum contact time. Although facilities to allow the addition at several alternate points is recommended, in no case may carbon be added near the point of chlorine application.

NR 811.59(3)(b) (b) The carbon shall be added as a premixed slurry or by means of a dry-feed machine if the carbon is properly ‘wetted’.

NR 811.59(3)(c) (c) Continuous agitation or resuspension equipment shall be provided to keep the carbon from depositing in the mixing chamber/slurry storage tank.

NR 811.59(3)(d) (d) Dust control shall be provided.

NR 811.59(3)(e) (e) The required dosage of carbon in a water treatment plant depends upon the tastes and odors involved. Provisions shall be made for adding sufficient amounts to meet peak demands.

NR 811.59(3)(f) (f) Powdered activated carbon shall be handled as a potentially combustible material. It shall be stored in a building or compartment as nearly fireproof as possible. Other chemicals may not be stored in the same compartment. A separate room shall be provided for carbon feed installations. Carbon feeder rooms shall be equipped with explosion-proof electrical outlets, lights, and motors.

NR 811.59(4) (4) Granular activated carbon. The requirements for granulated activated carbon are in s. NR 811.49.

NR 811.59(5) (5) Copper sulphate and other copper compounds. Continuous or periodic treatment of water with copper compounds to kill algae or other growths shall be controlled to prevent a level in excess of 1.0 mg/l as copper in the plant effluent or distribution system. Provisions shall be made for uniform distribution of the chemical.

NR 811.59(6) (6) Aeration. The requirements for aeration are in s. NR 811.45.

NR 811.59(7) (7) Potassium permanganate. The department may approve application of potassium permanganate if the treatment will be controlled to insure that no residual color will be present in the finished water.

NR 811.59(8) (8) Ozone. Ozonation may be used as a means of taste and odor control. Adequate contact time shall be provided to complete the chemical reactions involved. Ozone is generally more desirable for treating water with high threshold odors. Requirements for ozonation are contained in s. NR 811.54.

NR 811.59(9) (9) Other methods. Any other methods of taste and odor control may be allowed by the department only after laboratory or pilot plant tests or both.

NR 811.59(10) (10) Flexibility. Plants treating water known to have taste and odor problems shall be provided with equipment and multiple chemical addition points to provide several alternative control processes.

NR 811.59 Note Note: Refer to subch. VI, for requirements for the storage, handling and application of chemicals in treating surface waters.

NR 811.59 History History: CR 09-073: cr. Register November 2010 No. 659, eff. 12-1-10.

NR 811.60 NR 811.60 Ultraviolet (UV) Light. Ultraviolet light technology is a primary disinfectant typically used for Cryptosporidium and Giardia lamblia inactivation of both surface water and groundwater supplies. The U.S. Environmental Protection Agency Ultraviolet Disinfection Guidance Manual, EPA 815-D-03-007 dated June 2003, which is incorporated by reference, shall be used as the basis for the validation, design, and operation of all ultraviolet light systems. Ultraviolet light disinfection systems shall meet the requirements of ANSI/NSF standard 55 Class A dated August 13, 2021, which is incorporated by reference. Water systems designed to provide ultraviolet light disinfection shall comply with all of the following:

NR 811.60 Note Note: A copy of the U.S. Environmental Protection Agency Ultraviolet Disinfection Guidance Manual, EPA 815-D-03-007 dated June 2003 is available for inspection at the Legislative Reference Bureau and may be obtained for personal use from the U.S. Environmental Protection Agency, epa.gov. A copy of ANSI/NSF standard 55 Class A dated August 13, 2021 is available for inspection at the Legislative Reference Bureau and may be obtained for personal use from NSF International, nsf.org.

NR 811.60(1) (1) Treatment objectives. The target pathogen and the target log inactivation shall be used to identify the corresponding required UV dose.

NR 811.60(2) (2) Water quality considerations and pretreatment. In order to provide adequate disinfection treatment, some water sources may need treatment prior to ultraviolet light disinfection. UV disinfection of surface water sources shall follow filtration. Department approval for specific pretreatment requirements is required if any of the parameters in Table No. 3 are exceeded in the water to be treated by ultraviolet light.

NR 811.60(3) (3) Validation. Ultraviolet light treatment devices shall be validated by a third party entity in accordance with the U.S. Environmental Protection Agency Ultraviolet Disinfection Guidance Manual EPA 815-D-03-007 dated June 2003 or another validation standard as approved by the department. The final installation shall be equivalent or more protective than the validation testing installation.

NR 811.60 Note Note: A copy of the U.S. Environmental Protection Agency Ultraviolet Disinfection Guidance Manual, EPA 815-D-03-007 dated June 2003 is available for inspection at the Legislative Reference Bureau and may be obtained for personal use from the U.S. Environmental Protection Agency, www.epa.gov.

NR 811.60(4) (4) Materials. The ultraviolet light housing shall be type 304 or type 316L stainless steel.

NR 811.60(5) (5) Design.

NR 811.60(5)(a) (a) The ultraviolet treatment device shall be designed to provide a UV light dose of a minimum of 40 millijoules per square centimeter (mJ/cm2) and shall also deliver the target dose as prescribed by s. NR 810.62 by operating within the validated operating conditions for that particular unit.

NR 811.60(5)(b) (b) The ultraviolet treatment assemblies shall be designed to allow visual observation, cleaning, and replacement of the lamp, lamp sleeves, and sensor window or lens.

NR 811.60(5)(c) (c) All ultraviolet lamps shall be housed in type 214 quartz sleeves.

NR 811.60(5)(d) (d) Where in-situ cleaning of the lamp sleeves is proposed, the design shall protect the potable water from cleaning solutions.

NR 811.60(5)(d)1. 1. When off-line chemical cleaning systems are used, the UV enclosure shall be removed from service, drained, flushed with an NSF/ANSI Standard 60 certified solution, drained, and rinsed before being placed back in service.

NR 811.60(5)(d)2. 2. On-line systems that use wipers or brushes may use chemical solutions provided they are NSF/ANSI Standard 60 certified.

NR 811.60(5)(e) (e) An automatic shutdown valve shall be installed in the water supply line prior to the ultraviolet treatment device. When power is not provided the valve shall be in the closed position.

NR 811.60(5)(f) (f) The inlet and outlet piping to the reactors shall assure that the UV dose delivery is equal to or greater than the UV dose delivered during validation.

NR 811.60(5)(g) (g) The flow to each reactor shall be equally distributed and metered.

NR 811.60(5)(h) (h) Valves shall be provided to allow isolating and removing from service each UV reactor.

NR 811.60(5)(i) (i) Reactors shall be provided with air relief and pressure control valves per manufacturer requirements.

NR 811.60(5)(j) (j) UV transmittance (UVT) analyzers shall be provided if UVT is part of the dose monitoring strategy.

NR 811.60(5)(k) (k) Sample taps shall be provided downstream of each reactor.

NR 811.60(6) (6) Controls.

NR 811.60(6)(a) (a) A delay mechanism shall be installed to provide sufficient lamp warm-up prior to allowing water to flow from the ultraviolet treatment unit.