NR 110.26(6)(a)1.1. Aerobic digesters shall be designed to provide effective air mixing, reduction of organic matter, supernatant separation and sludge concentration. NR 110.26(6)(a)2.2. The digester detention time may be calculated based upon the factors indicated in subd. 1. If such calculations are not done, the following minimum requirements shall be met: NR 110.26(6)(a)2.a.a. A minimum of 15 days detention time shall be provided for waste activated sludge and 20 days for primary sludge or a combination of primary and waste activated sludge. Where sludge temperature is lower than 10°C (50°F), additional time shall be provided; and NR 110.26(6)(a)2.b.b. The volatile suspended solids loading may not exceed 1.60 kilograms per cubic meter per day (100 pounds per 1,000 cubic feet per day) in the digestion unit. Lower loading rates may be necessary depending on temperature, type of sludge and other factors. NR 110.26(6)(a)3.3. The aeration system for aerobic digesters shall be capable of meeting the oxygen requirements of par. (b), or the mixing requirements of par. (c), whichever is greater. NR 110.26(6)(b)1.1. Aeration systems shall be capable of maintaining a minimum digester dissolved oxygen concentration of one milligram per liter. NR 110.26(6)(b)2.2. In the absence of experimentally determined values, the design oxygen requirements for aerobic digesters shall be 2.0 kilograms oxygen per kilogram (2.0 pounds oxygen per pound) anticipated volatile suspended solids reduction. An additional 1.8 kilograms oxygen per kilogram (1.8 pounds oxygen per pound) of BOD5 applied to the digester by primary sludge shall be supplied. NR 110.26(6)(c)2.2. Diffused aeration systems shall be capable of delivering a minimum air flow rate of 30 cubic meters per minute per 1,000 cubic meters (30 cubic feet per minute per 1,000 cubic feet) of digester volume. NR 110.26(6)(c)3.3. Mechanical aerators shall deliver 26.3 kilowatts per 1000 cubic meters (1.0 horsepower per 1,000 cubic feet) of digester volume. NR 110.26(6)(e)(e) Supernatant withdrawal. Aerobic digesters shall be equipped for supernatant draw-off. It is recommended that multi-level draw-off be provided. NR 110.26(7)(a)(a) Lime stabilization. Sufficient lime shall be added to produce a pH of 12 after 2 hours of contact. NR 110.26(7)(b)(b) Composting. Static aerated pile, within vessel, or windrow composting methods shall be maintained at a minimum operating temperature of 40°C (104°F) for at least 5 days. For 4 hours during this period the temperature must exceed 55°C (131°F). Composting design, siting and operation shall be done in accordance with chs. NR 204 and 500 to 538. NR 110.26(7)(c)(c) Other methods. Other methods or operating conditions may be acceptable for sludge stabilization if pathogens and volatile solids are reduced to an extent equivalent to anaerobic digestion. NR 110.26(8)(a)1.1. The drying bed area shall be calculated based upon such factors as climatic conditions, character and volume of sludge to be dewatered, the method and character of sludge removal and other methods of sludge disposal. At least 0.19 square meters (2 square feet) of drying bed area per capita population equivalent shall be provided when the drying bed is the primary method of dewatering, and 0.09 square meters (1 square foot) per capita population equivalent if it is to be used as a back-up dewatering unit. The bed area shall be increased by 25% if the beds are paved. NR 110.26(8)(a)3.3. Percolation type drying beds shall meet the following conditions: NR 110.26(8)(a)3.a.a. The lower course of gravel around the underdrains shall be properly graded and shall be at least 30 centimeters (one foot) in depth, extending at least 15 centimeters (6 inches) above the top of the underdrains. It is desirable to place this in 2 or more layers. At least 8 centimeters (3 inches) of the top layer shall consist of gravel 3 to 6 millimeters (1/8 to 1/4 inches) in size. NR 110.26(8)(a)3.b.b. The top course shall consist of at least 15 to 23 centimeters (6 to 9 inches) of clean, medium to coarse, sand with a grain size of 1 to 3 millimeters in diameter. The finished sand surface shall be level. NR 110.26(8)(a)3.c.c. Underdrains shall be clay pipe or concrete drain tile at least 10 centimeters (4 inches) in diameter laid with open joints. Underdrains shall be spaced not more than 6 meters (20 feet) apart. NR 110.26(8)(a)3.d.d. An impervious layer shall be provided immediately beneath the lower course to prevent the downward movement of filtrate into the groundwater. NR 110.26(8)(a)4.4. Paved surface drying beds may be used if adequate center or side drains are provided. If partially paved drying beds are used, they shall be designed with consideration for space requirement to operate mechanical equipment for removing the dried sludge. NR 110.26(8)(a)5.5. Sludge influent piping to the beds shall terminate at least 30 centimeters (one foot) above the surface and be so arranged that the beds will drain. Concrete splash plates for percolation type beds shall be provided at sludge discharge points. NR 110.26(8)(a)6.6. Walls shall be watertight and extend 38 to 46 centimeters (15 to 18 inches) above and at least 15 centimeters (6 inches) below the surface of the beds. Outer walls shall be curbed to prevent soil from washing onto the beds. NR 110.26(8)(a)7.7. Drying beds shall be arranged to facilitate sludge removal. Concrete truck tracks shall be provided for all sludge beds. Pairs of tracks shall be on 6 meter (20-foot) centers. NR 110.26(8)(b)1.1. The bottom of the lagoons must be at least 1.25 meters (4 feet) above the maximum seasonal high groundwater level and at least 3 meters (10 feet) above bedrock. The bottom of the lagoons shall be constructed in accordance with s. NR 110.24. NR 110.26(8)(b)3.3. The area required will depend on design conditions. At least 2 lagoons shall be provided. NR 110.26(8)(b)4.4. Lagoons shall be adequately isolated to avoid creating nuisances. NR 110.26(8)(c)1.1. ‘General.’ Provision shall be made to maintain sufficient continuity of service so that sludge may be dewatered without accumulation beyond storage capacity. Design calculations or pilot plant data shall be submitted to justify the basis of design and equipment. NR 110.26(8)(c)2.2. The capacity of vacuum filters, centrifuges, filter presses, belt filters or other mechanical dewatering facilities shall be sufficient to dewater the sludge produced with the largest unit out of service. NR 110.26(8)(c)3.3. There shall be provided at least one back-up vacuum pump and one back-up filtrate pump for each vacuum filter installation. The vacuum filter shall be designed to allow for the easy removal and replacement of the vacuum pump and filtrate pump. NR 110.26(8)(d)(d) Drainage and filtrate disposal. The drainage from drying beds or shallow lagoons and the filtrate from dewatering units shall be returned to the sewage treatment process at appropriate points. NR 110.26(8)(e)(e) Other dewatering facilities. If other methods of reducing the quantity of sludge are proposed, a detailed description of the process and design data shall accompany the plans. NR 110.26(9)(a)(a) Incineration. Adequate provisions for residue disposal and air pollution control shall be provided. The appropriate requirements of chs. NR 415, 204 and 500 to 538 shall be met. NR 110.26(9)(b)(b) Other reduction facilities. If other methods of reducing the quantity of sludge are proposed, a detailed description of the process and design data shall accompany the plans. NR 110.26(10)(a)(a) General. Sludge storage shall be provided by facilities in accordance with ch. NR 204. A detailed description of the wastewater treatment process and design data shall accompany the plans for the proposed storage facility. Sludge storage facilities shall be designated and operated to maintain compliance with the groundwater quality standards in ch. NR 140. In the event a sludge storage facility is temporary, it shall be abandoned in such a manner so as to prevent safety, environmental and aesthetic problems from occurring. The department shall be notified in writing if the storage facility is to be abandoned and how abandonment will be accomplished. NR 110.26(10)(b)1.1. Sludge storage facilities may not be located within the following distances of a water supply well. NR 110.26(10)(b)3.3. A minimum separation distance of 1.25 meters (4 feet) shall be maintained between the bottom of storage lagoons and the highest recorded or indicated seasonal groundwater table elevation. NR 110.26(10)(b)4.4. A minimum separation distance of 3 meters (10 feet) shall be maintained between the bottom of storage lagoons and bedrock. NR 110.26(10)(c)1.1. Lagoon sludge storage facilities shall be designed to facilitate easy addition and removal of sludge without causing damage to the facility. NR 110.26(10)(c)3.3. The maximum lagoon depth shall be 6 meters (20 feet). The depth may be increased by the department on a case-by-case basis. NR 110.26(10)(d)1.1. Storage tanks shall be designed, installed and maintained to prevent leaks due to corrosion or structural failure. NR 110.26(10)(d)2.2. Liquid sludge storage facilities shall be designed with mixing capabilities to completely mix the tank contents. NR 110.26(10)(d)3.3. Supernatant withdrawal capability is recommended if the solids content of the sludge is less than 5%. NR 110.26(10)(d)4.4. Sampling ports shall be provided on both the influent and effluent lines to the tank. It is recommended that sample ports be equipped with drainage capabilities or other provisions to allow for a means to sample the tank effluent without actual discharge. NR 110.26(10)(e)1.1. Permanent and temporary cake storage facilities shall be designed to minimize odors and to protect surface waters, groundwaters and soil. NR 110.26(10)(e)3.3. Cake storage facilities designed as pits shall provide a method of draining-off and collecting precipitation. NR 110.26(10)(e)4.4. All sludge stored at an intermediate term cake storage facility shall be covered with a temporary cover. At a minimum, the cover shall be a 4 mil polyethylene cover or equivalent. The cover shall be anchored or otherwise secured. NR 110.26(10)(e)5.5. All sludge stored at a long term cake storage facility shall be covered with a permanent cover. NR 110.26(10)(f)(f) Monitoring wells. Monitoring wells may be required on a case-by-case basis. Construction of monitoring wells shall comply with the requirements of s. NR 110.25 (5) and ch. NR 141. NR 110.26(10)(g)(g) Amount of storage. Appropriate sludge storage and length of storage shall be provided in accordance with ch. NR 204 and this chapter. The required storage capacity may not include storage in clarifiers, oxidation ditches or aeration basins. However, digestive capacity that is greater than the digestive requirements can be considered as storage and can be used in calculating the amount of available storage. NR 110.26(11)(a)1.1. Liquid sludge shall be transported in an enclosed watertight unit from treatment plant to disposal site. NR 110.26(11)(a)2.2. All sludge field spreading equipment shall be provided with a control so that the discharge valve can be opened and closed by the driver while the vehicle is in motion. NR 110.26(11)(b)(b) Semi-solid cake. Sludge cake shall be transported in a covered watertight unit to prevent leakage of sludge moisture released in transit. Provision shall be taken to prevent the spilling of sludge from the vehicle while in transit and to prevent an odor nuisance while in transit. NR 110.26(12)(12) Ultimate disposal. The final use or disposal of sludge shall be regulated through the WPDES permit, this chapter and ch. NR 204 which comply with all applicable provisions of the clean water act (CWA) section 405 and 40 CFR 503. NR 110.26 HistoryHistory: Cr. Register, November, 1974, No. 227, eff. 12-1-74; r. and recr. Register, February, 1983, No. 326, eff. 3-1-83, am. (9), (12) (a) 3. and (c), r. and recr. (10) and cr. (12) (d), Register, November, 1990, No. 419, eff. 12-1-90; correction in (7) (b) made under s. 13.93 (2m) (b) 7., Stats., Register, September, 1995, No. 477; am. (2) (e) 1., (7) (b), (9) (a), (10) (a), (c) 1., 2. and (11) (a) 2., r. (10) (c) 4., 5., (f) 2. and 3., renum. (10) (d) to (f) 1. to be (10) (e) to (g) and am. (e) 6., (g) (intro.) and 1., cr. (10) (d), r. and recr. (12), Register, December, 1995, No. 480, eff. 1-1-96; correction in (5) (d) 4. was made under s. 13.93 (2m) (b) 7., Stats., Register, May, 2001, No. 545; corrections in (5) (d) 4., (7) (b) and (9) (a) made under s. 13.92 (4) (b) 7., Stats., Register February 2010 No. 650; corrections in (5) (b) 1. d. and (8) (b) 1. made under s. 13.92 (4) (b) 1. and 7., Stats., Register July 2010 No. 655; correction in (5) (d) 4. made under s. 13.92 (4) (b) 7., Stats., Register January 2012 No. 673. NR 110.27NR 110.27 Requirements for certified or registered laboratory. Bacteriological analyses of groundwater samples, and all radiological analyses, shall be performed by the state laboratory of hygiene or a laboratory certified or approved by the department of health services. Other laboratory test results for those pollutants which are required by the WPDES permit to be monitored and which are submitted to the department in support of facility plans or plans and specifications under this chapter shall be performed by a laboratory certified or registered under ch. NR 149. The department may require, on a case-by-case basis, that certain other laboratory test results submitted to the department be performed by a certified or registered laboratory. The following tests are excluded from this requirement:
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