NR 811.54(4)(c)
(c) Contact vessels shall be made of reinforced poured concrete. All reinforcement bars shall be covered with a minimum of 1.5 inches of concrete. Ozone resistant interior coatings shall be approved by the department in accordance with s.
NR 810.09 (5). Smaller contact vessels may be made of stainless steel, fiberglass, or other material which will be stable in the presence of residual ozone and ozone in the gas phase above the water level.
NR 811.54(4)(d)
(d) Contact chambers shall be of sufficient depth and size to allow for adequate contact time and freeboard for foaming where applicable. The depth of water in bubble diffuser contactors shall normally be a minimum of 18 feet unless a shallower depth can be justified to the department. A minimum freeboard of 3 feet shall be provided where foaming will be an issue.
NR 811.54(4)(e)
(e) The contact time for disinfection shall be determined based on the required inactivation CT values for viruses,
Giardia lamblia, and
Cryptosporidium contained in ss.
NR 810.59,
810.60, and
810.61. The minimum contact time shall be 10 minutes. A shorter contact time may be approved by the department if justified by appropriate design and CT considerations. Sufficient ozone capacity and contact chamber size shall be provided to achieve the desired CT value when injecting ozone into only one of the 2 contact chambers. The diffusion system shall normally work on a countercurrent basis such that the ozone shall enter through porous diffusers at the bottom of the vessel and water shall enter from the top of the vessel. Countercurrent flow shall be provided in all chambers of the vessels. Co-current diffusion systems shall only be approved by the department where adequate justification can be supplied.
NR 811.54(4)(f)
(f) For ozone applications in which precipitates are formed, such as with iron and manganese removal, porous diffusers may not be used.
NR 811.54(4)(g)
(g) Where taste and odor control is of concern, multiple application points and contactors shall be considered.
NR 811.54(4)(h)
(h) A system shall be provided between the contactor and the off-gas destruct unit to remove foam from the air and return the froth to the contactor or other location acceptable to the department when foam will be an issue. A potable water spray system shall be placed in the contactor head space if foaming is expected to be excessive.
NR 811.54(4)(i)
(i) All openings into the contactor for pipe connections, hatchways, etc., shall be properly sealed to prevent the escape of ozone using welds or ozone resistant gaskets such as Teflon or Hypalon.
NR 811.54(4)(j)
(j) A pressure or vacuum relief valve shall be provided in the contactor as appropriate. Pressure or vacuum relief valve discharge piping shall be piped to a location where there will be no damage to the ozone destruction unit or an uncontrolled release of ozone.
NR 811.54(4)(k)
(k) Sampling faucets and monitors shall be provided on the inlet and outlet of each contact chamber to monitor water quality and the ozone residual. If allowed by the department, a portable monitor or a comparable testing method may be used to analyze water collected from sample taps provided on the inlet and outlet of each contact chamber.
NR 811.54(4)(L)
(L) A water meter shall be provided on the inlet to the contact chambers to measure water flow.
NR 811.54(4)(m)
(m) If required by the department, contactors or reservoirs used as contactors shall be fitted with the improvements necessary to allow sampling of water from intermediate points for ozone residual.
NR 811.54(4)(n)
(n) All contactors shall have provisions for cleaning, maintenance, and drainage. Each contactor compartment shall also be equipped with an access hatchway.
NR 811.54(5)
(5)
Ozone destruction. Ozone destruction shall meet the following requirements:
NR 811.54(5)(a)
(a) A method or combination of methods for destroying or recirculating the final off gas from the ozone contactors shall be provided to meet safety and air quality standards. Acceptable methods include:
NR 811.54(5)(a)4.
4. Recycling to some point in the treatment system in addition to the installation of destruction equipment.
NR 811.54(5)(b)
(b) A detectable ozone residual may not carry over into the distribution system.
NR 811.54(5)(c)
(c) The maximum allowable air ozone concentration in the destruction unit discharge is 0.1 ppm by volume.
NR 811.54(5)(d)
(d) At least 2 units shall be provided which are each capable of handling the entire gas flow unless the second unit is deemed unnecessary by the department.
NR 811.54(5)(e)
(e) Exhaust blowers shall be provided in order to draw ozone off-gas from the contactors into the destruct unit.
NR 811.54(5)(f)
(f) Catalysts shall be protected from foam, moisture and other impurities that may harm the catalyst.
NR 811.54(5)(g)
(g) The catalyst and heating elements shall be located where they can be easily reached for maintenance.
NR 811.54 Note
Note: In order to reduce the risk of fires, the use of units that operate at lower temperatures is encouraged, especially where high purity oxygen is the feed gas.
NR 811.54(6)
(6)
Piping materials. Piping materials used in ozone service shall meet the following requirements:
NR 811.54(6)(a)
(a) Only low carbon 304L and 316L stainless steel piping shall be used for ozone service. Alternative piping materials may be approved by the department on a case-by-case basis.
NR 811.54(6)(c)
(c) Rubber components may not be used in contact with ozone.
NR 811.54(7)(a)(a) Connections on stainless steel piping used for ozone service are to be welded where possible.
NR 811.54(7)(b)
(b) Connections with meters, valves, or other equipment are to be made with flanged joints with ozone resistant gaskets, such as Teflon or Hypalon. Screwed fittings and field-cut threaded connections may not be used.
NR 811.54(7)(c)
(c) A positive closing plug or butterfly valve and a leak-proof backflow prevention check valve system shall be provided in the piping between the generator and the contactor for pressurized ozone generation systems.
NR 811.54(8)
(8)
Instrumentation. Instrumentation shall meet the following requirements:
NR 811.54(8)(a)
(a) Pressure gauges shall be provided at the discharge from the air compressor, at the inlet to the refrigerator dryers, at the inlet and outlet of the desiccant dryers, at the inlet to the ozone generators and contactors, and at the inlet to the ozone destruction unit.
NR 811.54(8)(b)
(b) Each generator shall have a trip which shuts down the generator when the wattage exceeds a preset level. It is recommended that electric power meters be provided for measuring the electric power supplied to the ozone generators.
NR 811.54(8)(c)
(c) Dew point monitors shall be provided for measuring the moisture of the feed gas from each desiccant dryer. Where there is potential for moisture entering the ozone generator from downstream of the unit or where moisture accumulation can occur in the generator during shutdown, post-generator dew point monitors shall be used.
NR 811.54(8)(d)
(d) Air flow meters shall be provided for measuring the air flow from the desiccant dryers to each of the ozone generators, the air flow to each contactor, and the purge air flow to the desiccant dryers.
NR 811.54(8)(e)
(e) Temperature gauges shall be provided for the inlet and outlet of the ozone cooling water and the inlet and outlet of the ozone generator feed gas, and, if applicable, for the inlet and outlet of the ozone power supply cooling water.
NR 811.54(8)(f)
(f) Water flow meters shall be installed to monitor the flow of cooling water to the ozone generators and, if applicable, to the ozone power supply.
NR 811.54(8)(g)
(g) At a minimum, ozone monitors shall be installed and maintained to measure ozone concentrations in both the feed-gas and the off-gas from the contactor and the off-gas from the destruct unit. Monitors or a comparable testing method shall also be provided for measuring ozone residuals in water in accordance with subs.
(4) and
(5) (b). The number and location of ozone residual monitors shall be such that the amount of time that the water is in contact with the ozone residual can be determined.
NR 811.54(8)(h)
(h) Ambient air ozone monitors shall be installed in rooms where exposure to ozone is possible.
NR 811.54(9)
(9)
Alarms. The installation of alarm and shutdown systems shall meet the following requirements:
NR 811.54(9)(a)
(a) A dew point alarm and shutdown shall shut down the generator in the event the system dew point exceeds -60
°C (-76
°F).
NR 811.54(9)(b)
(b) An ozone generator cooling water flow alarm and shutdown shall shut down the generator in the event that cooling water flows decrease to the point that generator damage could occur.
NR 811.54(9)(c)
(c) An ozone power supply cooling water flow alarm and shutdown shall shut down the power supply in the event that cooling water flow decreases to the point that power supply damage could occur.
NR 811.54(9)(d)
(d) An ozone generator cooling water temperature alarm and shutdown shall shut down the generator if either the inlet or outlet cooling water exceeds the designated preset temperature.
NR 811.54(9)(e)
(e) An ozone power supply cooling water temperature alarm and shutdown shall shut down the power supply if either the inlet or outlet cooling water exceeds the designated preset temperature.
NR 811.54(9)(f)
(f) An ozone generator inlet feed-gas temperature alarm and shutdown shall shut down the generator if the feed-gas temperature exceeds the designated preset value.
NR 811.54(9)(g)
(g) An ambient air ozone concentration alarm and shutdown shall sound when the ozone level in the building ambient air exceeds 0.1 ppm or a lower value chosen by the water supplier. Ozone generator shutdown shall automatically occur when the building ambient air ozone level exceeds 0.3 ppm or a lower value chosen by the water supplier.
NR 811.54(9)(h)
(h) An ozone destruct temperature alarm shall sound when the temperature exceeds the designated preset value.
NR 811.54(9)(i)
(i) Audible alarms and warning lights shall be installed and maintained to insure operators are alerted to improper operating or hazardous conditions.
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(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)(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.
