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)(b) Sludge drying lagoons.
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)2.2. Lagoons may not be more than one meter (39 inches) in depth.
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)(c) Mechanical dewatering facilities.
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)(c)4.4. The dewatering area shall be ventilated.
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)(9)Sludge reduction.
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)(10)Sludge storage facilities.
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)(b) Separation distances.
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)1.a.a. 1000 feet from a community public water supply well;