NR 110.13 NoteNote: A department approval of a sanitary sewer overflow structure does not eliminate or alleviate the requirement that prohibits sewage treatment facility overflows in s. NR 210.21.

NR 110.13 HistoryHistory: Cr. Register, November, 1974, No. 227, eff. 12-1-74; am. (2), Register, December, 1978, No. 276, eff. 1-1-79; r. and recr. Register, February, 1983, No. 326, eff. 3-1-83; corrections in (1) made under s. 13.93 (2m) (b) 7., Stats., Register, September, 1995, No. 477; corrections in (1) (d) 2. and 3. were made under s. 13.93 (2m) (b) 7., Stats., Register, May, 2001, No. 545; CR 09-123: am. (1) (d) 1., 2., (2) (i), (k) 1., (5) (a) and (e) to (h) Register July 2010 No. 655, eff. 8-1-10; correction in (1) (d) 3. made under s. 13.92 (4) (b) 7., Stats., Register January 2012 No. 673; CR 12-027: cr. (6) Register July 2013 No. 691, eff. 8-1-13.

NR 110.14(1)(b)(b) Design report. A design report shall be submitted with plans and specifications for all new sewage lift stations as well as the major rehabilitation of existing lift stations. Major lift station rehabilitation may include, but is not limited to, replacing pumps with larger units or changing the type of lift stations. The design report shall comply with the facilities planning requirements of s. NR 110.11, and shall contain the detailed design calculations for the lift station design capacity.

NR 110.14(2)(a)1.1. Lift stations may be constructed in floodplains provided the floodproofing requirements of ss. NR 116.16 and 116.17 are met.

NR 110.14(2)(a)2.2. Where practical, lift stations shall be located off the traffic way of streets and alleys.

NR 110.14(2)(a)3.3. Lift stations shall be located with a minimum separation distance of 60 meters (200 feet) from community water system well, and a minimum separation distance of 30 meters (100 feet) from a private water well or any other well subject to ch. NR 812. A lesser separation distance from a community water system well may be approved if hydrogeologic information is provided to the department to indicate the lesser separation distance would provide adequate protection of a well from contamination. When a lift station is proposed within 60 meters (200 feet) of a community water system well, or 30 meters (100 feet) of private water wells or any other well subject to ch. NR 812, the location of the well shall be shown on the engineering plans. Gravity or pressure sewers connecting to lift stations shall be separated from water supply wells in accordance with s. NR 110.13 (1) (d).

NR 110.14(2)(b)1.1. Pumping rates for lift stations integral to collection systems shall be determined in the same manner as the flows for the sewers contributory to the lift station and in accordance with the provisions of s. NR 110.11 (1) (d).

NR 110.14(2)(b)2.2. Pumping rates for lift stations which operate as part of sewage treatment facilities shall be determined in the same manner as the design flow for the treatment facility in accordance with s. NR 110.15 (4) (c).

NR 110.14(2)(b)3.3. Where possible, the pumping rate shall be designed to approximate the peak hour influent design flow rate to the lift station. For main lift stations or lift stations associated with treatment facilities, or in cases where large fluctuations of flow are known to occur, the use of variable speed pumps, or multiple constant speed pumps may be required by the department.

NR 110.14(3)(a)(a) Type. Sewage lift stations in general use fall into 7 types: wet well/dry well, submersible, suction lift, screw pump, pneumatic ejector, grinder pump and septic tank effluent pump.

NR 110.14(3)(b)1.1. Dry wells, including their superstructure, shall be completely separated from wet wells. Common walls shall be gas tight.

NR 110.14(3)(b)2.2. Provisions shall be made in all types of lift stations to facilitate removal of pumps, motors, and other mechanical and electrical equipment without entry into the wet well.

NR 110.14(3)(b)3.3. Permanent ladders or steps may not be provided in the wet wells with the possible exception of built-in place lift stations, in which stairways in the wet wells may be approved if there are special maintenance needs or physical conditions that prevent the provision of necessary access by any other reasonable means. A safe means of access shall be provided to dry wells containing equipment requiring inspection or maintenance. If a dry well is over 6 meters (20 feet) deep, an offset shall be made in the entrance ladder with an intermediate landing at approximately mid-depth. Where an intermediate landing is used, the diameter of the landing area shall be at least 1.5 meters (5 feet), or an equivalent landing area shall be provided. Landings shall be provided with a suitable barrier to prevent an individual from falling past the intermediate landing to the lower level.

NR 110.14(3)(b)4.4. A caution sign shall be installed at top of entrances to wet wells. The caution sign shall provide a warning of the potential for hazardous gases in a confined space and indicate that there shall be no entry without proper equipment and supervision.

NR 110.14(3)(b)5.5. A sump pump shall be provided in a dry well to remove leakage or drainage. The sump pump discharge line shall be equipped with a check valve, and shall discharge above the maximum high water level of the wet well. A siphon break shall be provided when the sump pump discharge line enters at the high water level in the wet well. Pump seal water leakage shall be piped or channeled directly to the sump pit.

NR 110.14(3)(b)6.6. All floors and walkways shall be sloped to a point of drainage.

NR 110.14(3)(b)7.7. All wet wells shall be designed based on fill time and minimum pump cycle time. With any combination of influent flows and pumping rate, the minimum pump cycle time shall be greater than or equal to 5 minutes. The total fill time between pump on and off elevations in the wet well, at average design flow, may not exceed 30 minutes to prevent septicity.

NR 110.14(3)(b)8.8. The wet well floor shall have a minimum slope of one to one to the hopper bottom. The horizontal area of the hopper bottom may not be greater than necessary for proper installation and function of suction pipe intake or pump inlet.