NR 110.14(3)(i)4.4. All lift stations shall be equipped with an alarm system. The alarm system shall include audible and visual signals. The alarm system shall be activated in cases of power failure, pump failure, and at a predesignated high water level. It is also recommended that alarm systems be activated in the event of unauthorized entry or other lift station malfunction. The department may require that alarm systems be telemetered to responsible authorities for large or main lift stations.

NR 110.14(3)(j)1.1. At the design pumping rate, a cleansing velocity of at least 61 centimeters per second (2 feet per second) shall be maintained.

NR 110.14(3)(j)2.2. A combination automatic air relief and vacuum valve or an automatic or manual air relief valve shall be placed at each high point in the force main to prevent air locking.

NR 110.14(3)(j)3.3. When a force main enters the gravity sewer manhole, it shall discharge at a point not more than 60 centimeters (2 feet) above the spring line of the receiving sewer.

NR 110.14(3)(j)4.4. Friction losses through force mains shall be based on the Hazen and Williams formula or other acceptable method. The roughness coefficient “C” value used for design shall be noted on the design report.

NR 110.14 NoteNote: When the Hazen and Williams formula is used, the department recommends a “C” value between 100 and 125 be used for all pipe except plastic pipe. A “C” value between 120 and 140 is recommended for plastic pipe. When initially installed, force mains may have a significantly higher “C” value. The lower “C” value (higher coefficient of friction) should be considered when calculating the head at design conditions. The higher “C” value should be considered when calculating the minimum head in the pump operating range power requirements.

NR 110.14(4)(a)(a) Priming. Suction lift pumps shall be of the self-priming or vacuum primed type and shall comply with applicable requirements of sub. (3), except as modified in this subsection.

NR 110.14(4)(b)(b) Lift. The total dynamic suction lift may not exceed 6.0 meters (20 feet), unless the department approves pumps which exceed this specified limit based on certified pump performance curves and detailed calculations which justify the higher heads.

NR 110.14(4)(c)(c) Compartment separation. The pump equipment compartment shall be above grade, partially recessed in the ground or offset and shall be isolated from the wet well in a manner which will prevent the humid and corrosive sewer atmosphere from entering the equipment compartment. Wet well access may not be through the equipment compartment and shall be at least 61 centimeters (24 inches) in diameter or equivalent area.

NR 110.14(4)(d)(d) Electrical. Float type displacement switches and electronic transducers which are used in wet wells shall comply with the applicable requirements of sub. (5).

NR 110.14(5)(a)(a) Construction. Submersible pumps and motors shall be designed specifically for raw sewage use, and for total submergence during operation, and shall comply with the applicable requirements of sub. (3), except as modified in this subsection.

NR 110.14(5)(b)(b) Pump removal. Submersible pumps shall be readily removable and replaceable without dewatering the wet well or disconnecting any piping in the wet well. Removal of one submersible pump from the lift station may not interrupt the operation of other pumps in the station.

NR 110.14(5)(c)1.1. Electrical supply, control, and alarm circuits shall be designed to provide strain relief appurtenances. All junction boxes containing terminals and connectors shall be protected from corrosion by being located outside the wet well or through the use of a watertight seal. Junction boxes for motor power cable connections and for intrinsically safe control circuits shall meet the requirements of weatherproof equipment.

NR 110.14(5)(c)2.2. The motor control center shall be located outside the wet well and be protected by conduit seals or other appropriate measures meeting the requirements of the NEC to prevent the atmosphere of the wet well from gaining access to the control center. The explosion proof seals shall be located so the pump motor and the level control float switches or transducers can be removed and electrically disconnected at the respective junction box without destroying the seal.

NR 110.14(5)(c)3.3. Pump motor power cables shall be designed for flexibility and serviceability. Ground fault interruption protection shall be provided in accordance with the NEC requirements. Power cord terminal fittings shall be corrosion-resistant and constructed in a manner to prevent the entry of moisture into the cable, shall be provided with strain relief appurtenances, and shall be designed to facilitate field connecting.

NR 110.14(5)(d)(d) Explosion prevention. In order to minimize the potential for ignition of explosive gases in submersible lift stations, one of the following requirements shall be met:

NR 110.14(5)(d)1.1. Low water level controls may be set such that the pump motor will remain totally submerged at all times. The lift station shall be equipped with a low water alarm in addition to meeting the requirements of sub. (3) (i) 4., and which is distinguishable from the high water alarm.

NR 110.14(5)(d)2.2. The pump motor may be rated for compliance with the NEC explosion proof requirements of Class 1, Group D, Division 1 locations.

NR 110.14(6)(a)(a) Construction. The wet well and dry well lift stations shall be designed specifically for raw sewage use and shall comply with applicable requirements of sub. (3), except as otherwise provided in this subsection.

NR 110.14(6)(b)(b) Electrical. When float type displacement switches or electronic transducers are used to control the liquid level in the wet well, they shall comply with the applicable requirements of sub. (5).

NR 110.14(7)(a)(a) Applicability. Screw pumps may be approved by the department on a case-by-case basis upon submission of appropriate manufacturer’s data and the detailed design calculations.

NR 110.14(7)(b)(b) Construction. Screw pumps and motors shall be designed specifically for raw sewage use, and shall comply with applicable requirements of sub. (3).