Section NR 110.15 - General requirements for sewage treatment facilities(1) DESIGN REPORT. A design report shall be submitted with plans and specifications for all sewage treatment facilities. This report shall summarize the design hydraulic loading, design biochemical oxygen demand (BOD), suspended solids and other appropriate pollutant loading, the sizing of treatment units, pump capacities, design calculations for major treatment units, and explain any deviations from the preliminary facilities planning design information which is required by s. NR 110.09(1) (b).(2) EFFLUENT QUALITY. (a)Design. Sewage treatment facilities shall be designed to achieve compliance with the monthly and weekly average effluent limitations for biochemical oxygen demand (BOD) and total suspended solids contained in ch. NR 210, or other WPDES permit requirements, as appropriate, or with any more stringent water quality related effluent limitations required to achieve appropriate water quality standards derived from chs. NR 102 to 106, or from any federally promulgated water quality standard for any waters of the state.(b)Treatment during construction. During construction of new facilities, treatment shall be maintained at a level not less than that which existed prior to the start of construction.(3) PLANT LOCATION.(a)Flood protection.1. All sewage treatment facilities shall be located such that they are not subject to flooding.2. Any sewage treatment facility located in a floodplain, or suspected to be in a floodplain, will not be approved until the flood analysis requirements of s. NR 110.09(2) (n) are met.3. A sewage treatment facility may be located in the flood fringe providing the requirements of par. (c) and ss. NR 116.14, 116.15, 116.16 and 116.17 are met.4. All sewage treatment facilities which are located in a floodplain shall be floodproofed to an elevation of at least 2 feet above the regional flood elevation.5. Location of a land disposal system in a floodplain will be evaluated on a case-by-case basis.(b)Floodway construction.1. No new sewage treatment facility shall be located in a floodway as defined in ss. NR 116.03 and 116.11. A change in the zoning classification of a treatment facility site from floodway to flood fringe in accordance with the procedures specified in s. NR 116.21(6), will be acceptable only if the rezoning is complemented by the construction of a dry land access as defined in par. (c). When the facility site is rezoned from floodway to flood fringe, the dry land access requirement will not be waived.2. Any existing sewage treatment facility which is located in a floodway shall meet the requirements of subd. 1. if the expansion or upgrading of the facility is greater than 50% of the value of the facility. Value is defined in par. (c).3. Any existing sewage treatment facility which is located in a floodway will not have to comply with the requirements of subd. 1. if the expansion or upgrading of the facility is less than 50% of the value of the facility. In this instance, the dry land access requirements of par. (c) will not apply.(c)Accessibility.1. Sewage treatment facilities shall be accessible at all times. Sewage treatment facilities located in a flood fringe shall be accessible by dry land access. Dry land access is defined as a service road which has a minimum elevation of at least one foot above the regional flood elevation.2. The dry land access requirement may be waived by the department if one of the following criteria is met:a. The physical characteristics of the treatment site and the surrounding area pose practical difficulties for construction of dry land access, and the isolation of the sewage treatment facility during the regional flood is less than 24 hours for mechanical treatment facilities, or 5 days for lagoon systems. The duration of the regional flood shall be calculated using the methods described in s. NR 116.07; orb. The physical characteristics of the treatment site and the surrounding area pose practical difficulties for construction of dry land access, and the treatment facility access is inundated by less than one foot of water during the regional flood. In these instances, the access roads shall be stabilized and delineated; orc. The construction costs of the expansion or upgrading of an existing treatment facility are less than 50% of the value of the existing facility. The value of the existing facility shall be calculated by subtracting the 20-year total present worth of expanding or upgrading the existing facility from the 20-year total present worth of the most cost-effective treatment alternative located at another site which is not in a floodplain.(d)Isolation.1. In order to minimize any potential odor, noise, and nuisances caused by sewage treatment facilities, and to enhance plant security and reliability, sewage treatment facilities shall be isolated from commercial establishments and from buildings occupied or intended for residential use, and from land which is actively being developed for commercial or residential use. The following separation distances shall be maintained: a. 150 meters (500 feet) for mechanical treatment facilities, effluent holding and polishing ponds;b. 150 meters (500 feet) for seepage cells, ridge and furrow systems, and overland flow systems;c. 230 meters (750 feet) for aerated lagoons;d. 305 meters (1,000 feet) for off site sludge holding facilities and spray irrigation systems; ande. 460 meters (1,500 feet) for stabilization lagoons.2. The department may waive the requirements of subd. 1. if the requirements prevent implementation of the cost-effective treatment alternative at an existing sewage treatment facility site. When a waiver is requested, the owner shall demonstrate to the department that: a. The owner has made reasonable attempts to obtain an agreement from any affected property owner which states that the property owner has been informed of the potential nuisances which may result from the operation of the sewage treatment facilities and that the property owner does not object to the construction and operation of the sewage treatment facilities; andb. The treatment facility owner has enacted a zoning ordinance which prohibits future construction within the applicable separation distances, or has purchased sufficient land surrounding the sewage treatment facility to prevent future encroachment.3. The department may waive the requirements of subd. 1. if the requirements prevent construction of the cost-effective treatment alternative at a new site. When a waiver is requested the owner shall demonstrate that: a. The treatment facility has obtained from the affected property owners the agreements described in subd. 2. a. or that the proposed sewage treatment facility site is the only reasonably available site or, the costs associated with using another site would place an unreasonable or excessive financial burden on the community; andb. The treatment facility owner has enacted a zoning ordinance which prohibits future construction within the applicable separation distances, or has purchased sufficient land surrounding the proposed treatment facility site to prevent future encroachment.(e)Protection of water supply wells. Wastewater lagoons or storage structures shall be located with a minimum separation distance of 1,000 feet from a community water system well, and 100 feet from a private water system well or any other well subject to ch. NR 812. Wastewater treatment plant effluent pipes shall be located with a minimum separation distance of 50 feet from a private water system well or any other well subject to ch. NR 812.(4) DESIGN OF SEWAGE TREATMENT FACILITIES. (a)Conformance with facilities plan. The design capacity for municipally owned sewage treatment facilities shall be in accordance with s. NR 110.09(2) (j). Privately owned domestic sewage treatment facilities shall provide design capacity for the estimated population 20 years from the time of start-up of the facility unless the cost-effective staging analysis in s. NR 110.09(2) (j) 4. justifies a lesser design staging period.(b)Organic loading.1. The domestic design biochemical oxygen demand and suspended solids loading for upgrading or expanding existing sewage treatment facilities, or for the construction of new sewage treatment facilities to replace an existing facility shall be based on actual sewage and operating records from the existing facilities. The design shall include an appropriate growth increment.2. When actual operating data is not available, the design loading shall be based on a contribution of 0.08 kilograms (0.17 pounds) of biochemical oxygen demand per capita per day and 0.09 kilograms (0.20 pounds) of suspended solids per capita per day. When garbage grinders are used in areas tributary to a sewage treatment facility, the design basis shall be increased to 0.10 kilograms (0.22 pounds) of biochemical oxygen demand per capita per day, and 0.22 kilograms (0.25 pounds) of suspended solids per capita per day.3. Sewage treatment facilities which will receive industrial or commercial wastewater shall be designed to include these waste flows.(c)Hydraulic loading. The design wastewater flow shall be estimated in accordance with s. NR 110.09(2) (j). When flow or water use records do not exist, the maximum hour design flow shall be estimated by multiplying the average design flow by the appropriate peaking factor shown in Table 2. Table 2
Community Size (population) | Peaking Factor |
Under 1,000 | 4 - 5 |
1,000 - 10,000 | 3.0 - 3.5 |
10,000 - 100,000 | 2.0 - 2.5 |
Over 100,000 | 1.5 - 2.0 |
(d)Sludge storage. Adequate sludge storage shall be provided as indicated in ss. NR 110.09(2) (h) 5 and 110.26(10).(5) DESIGN FEATURES. (a)Design of conduits. All piping and channels shall be designed to carry the peak design flow rate. The incoming sewer should be designed for unrestricted flow. Bottom corners of the channels must be filleted. Conduits shall be designed to avoid creation of pockets and corners where solids can accumulate. Suitable gates shall be placed in channels to seal off unused sections in which solids might accumulate. The use of shear gates or stop planks may be used in place of gate valves or sluice gates.(b)Arrangement of units. Component parts of the facility shall be arranged for greatest operating and maintenance convenience, flexibility, economy, continuity of effluent quality, and ease of installation of future units.(c)Flow measurement. Equipment for flow measurement and recording shall be provided for the total waste flow. Equipment for measuring flow streams within the treatment facility should be provided to aid facility operation.(d)Emergency operation. At least one of the following shall be provided to ensure continued operation of the sewage treatment facility in accordance with s. NR 210.08: 1. `Emergency power generator.' An emergency power generator with sufficient generating capacity to meet the sewage treatment facility power demands to comply with s. NR 210.08.2. `Two independent electrical transmission sources.' An electrical system connected to two independent transmission routes that receive power from the same electrical grid network which supplies power to the sewage treatment facility service area.3. `Holding facilities.' Holding facilities that have a capacity to detain the maximum day design flow for a maximum period of 24 hours.(e)New processes, methods and equipment. The department encourages the development of new process, methods, or equipment for the treatment of sewage. However, where new processes, methods, or equipment are proposed and where limited data is available which demonstrates the performance of the equipment, the department may require written certification that the use or design of the equipment is in accordance with the manufacturer's guidelines. Furthermore, the department may require the posting of a performance bond by the manufacturer.(f)Disinfection. Disinfection shall be provided in accordance with WPDES permit requirements.(g)Controlled diversion structures and equipment. Structures and equipment to enable controlled diversions shall be located and arranged to allow for proper maintenance of the sewage treatment facility. In all cases, it must be possible for each treatment unit to be independently removed from service. Note: Section NR 205.07(1) (u) 2. contains specific provisions associated with the use of controlled diversion structures and equipment and requires compliance with all permit effluent limitations during times of controlled diversion.
(h)Sewage treatment facility overflow structures. Sewage treatment facility overflow structures may be provided at an owner's discretion as a measure to protect sewage treatment facility integrity and treatment efficiency during severe operating conditions. Sewage treatment facility overflow structures may not be installed at the headworks of aerated or stabilization pond treatment systems. Sewage treatment facility overflow structures shall be designed in accordance with all the following requirements: 1. The overflow may be activated by either manual or automatic means. If automatically activated, a monitoring system shall be provided to detect the initiation time of the overflow and to provide an alarm signal to the sewage treatment facility operator or other responsible authority.2. The structure shall be designed to discharge only those wastewater flows above the peak flow rate that the sewage treatment facility can safely process without threatening loss of life, causing severe property damage, or compromising treatment processes, including the washout of biological media in the biological treatment process.3. Equipment shall be provided to measure the flow and sample the wastewater that is discharged from the structure. Note: A department approval of a sewage treatment facility overflow structure does not eliminate or alleviate the requirement that prohibits sewage treatment facility overflows in s. NR 210.21.
(i)Painting.1. The use of paints containing lead is prohibited. In order to facilitate the identification of piping, pipes shall be painted as follows: c. Potable water line-blue;f. Compressed air line-green;g. Nonpotable water line-blue with 15 centimeter (6 inch) red bands spaced 76 centimeters (30 inches) apart.2. In addition to the color code, each pipe shall be adequately labeled with a minimum of 2 labels in each room, crawl space or compartment.3. Existing treatment facilities which do not comply with the provisions of this subsection shall bring the facility into compliance at the time of any major upgrading or expansion of the facility. (j)Valve identification. All valves shall be identified in the plans and specifications and labeled during construction.(k)Operational considerations. All necessary tools and accessories for the facility operator's use shall be provided. Storage space and a work area shall also be provided. All equipment shall be located as to provide sufficient clearance for proper and convenient maintenance. All tanks, wet wells, channels and pipe systems shall be equipped with drains, valves, or sumps to facilitate draining for maintenance and repair.(l)Laboratory space and equipment. A treatment facility owner shall either include a laboratory for making the necessary analytical determinations and operating control tests, or contract with a neighboring facility or independent laboratory to have the analytical and operating control tests done.(m)Floor slope. Floor surfaces shall be sloped adequately to a point of drainage.(n)Erosion control during construction. Effective site erosion control shall be provided during construction. Project specifications shall detail erosion control methods. Manner of spoil material disposal shall also be detailed.(o)Construction materials. Materials shall be selected that are compatible with the wastewater characteristics. Dissimilar metals should be avoided to minimize galvanic action.(p)Sanitary facilities. Toilet, shower, lavatory, and locker facilities should be provided in sufficient numbers and convenient locations to serve the expected facility personnel. Toilet, shower, and lavatory facilities shall be provided in the following instances: 1. Any sewage treatment facility equipped with laboratory facilities;2. Any sewage treatment facility equipped with a potable water supply; or3. Any sewage treatment facility which has one or more full time operating personnel.(q)Safety.1. Sewage treatment facilities shall be enclosed with a fence to discourage entry of animals or unauthorized persons.2. Hand rails shall be installed around all treatment tanks and in other areas of the facility where the potential of falling exists.3. The department recommends the following safety measure be considered in the design of wastewater treatment facilities: a. Provision of first aid equipment;b. Posting of "No Smoking" signs in hazardous areas;c. Provision of protective clothing and equipment such as gas masks, goggles, gloves, hard hats, and safety harness;d. Portable blower and hose;e. Portable lighting equipment; andf. Nonpotable water supply bibs which are labeled.4. The safety and health rules set forth in ch. SPS 332, and appropriate federal and local safety codes shall be adhered to in the operation of wastewater treatment plants.5. Specific safety requirements for hazardous chemical handling are found in s. NR 110.22(4).6. Specific safety requirements for chlorination facilities are found in s. NR 110.23(2) (g).(6) WATER SUPPLY. (a)Potable supply. Any sewage treatment facility which has a laboratory shall be provided with a potable water supply.(b)Plumbing. Sewage treatment facility plumbing systems shall be designed in accordance with ch. SPS 382.(c)Connection to public water systems. Connection of a sewage treatment facility plumbing system to a public water system shall comply with the requirements of s. NR 811.25 and ch. SPS 382.(d)On-site wells. Construction of wells for supplying water to a sewage treatment facility shall comply with the requirements of the approval obtained under s. NR 812.09(4) (b).Wis. Admin. Code Department of Natural Resources NR 110.15
Cr. Register, November, 1974, No. 227, eff. 12-1-74; r. and recr. (1) (c), Register, March, 1978, No. 267, eff. 4-1-78; r. and recr. Register, February, 1983, No. 326, eff. 3-1-83, cr. (4) (d), Register, November, 1990, No. 419, eff. 12-1-90; corrections in (5) and (6) made under s. 13.93(2m) (b) 7, Stats., Register, September, 1995, No. 477; corrections in (5) (q) 4., (6) (b), and (c) were made under s. 13.93(2m) (b) 7, Stats., Register, May, 2001, No. 545; CR 09-123: am. (2) (a) and (4) (c), cr. (3) (e) Register July 2010 No. 655, eff. 8-1-10; corrections in (5) (q) 4., (6) (b) and (c) made under s. 13.92(4) (b) 7, Stats., Register January 2012 No. 673; CR 12-027: r. (2) (c) to (e), r. and recr. (5) (d), am. (5) (g), r. and recr. (5) (h) Register July 2013 No. 691, eff. 8-1-13.Amended by, CR 18-095: am. (6) (d) Register June 2020 No. 774, eff. 7-1-20; correction in (6) (b) made under s. 35.17, Stats., Register June 2020 No. 774, eff. 7/1/2020