(a) Pump Controls.
(1) A lift station pump must operate automatically, based on the water level in a wet well. Pump controls must be designed to prevent surcharges in the collection system and must be designed to prevent adverse effects on the operation of the wastewater treatment facility.
(2) The location of a wet well water level mechanism must ensure that the mechanism is unaffected by currents, rags, grease, or other floating materials.
(3) A wet well water level mechanism must be accessible without entering the wet well.
(4) Wet wells with a bubbler system require dual air supplies and dual controls.
(5) Motor control centers must be mounted high enough above grade, but in no case less than 4.0 inches above grade, to prevent water intrusion and corrosion from standing water in the enclosure. Motor control centers must also be protected from the entrance of corrosive gases from wet wells or piping.
(6) Electrical equipment and electrical connections in a wet well or a dry well must meet National Fire Protection Association 70 National Electrical Code® explosion prevention requirements, unless continuous ventilation is provided.
(7) Electronic wet well level control systems must also use a float switch or similar manual backup.
(8) Wet well control settings must be designed to discourage septic conditions in a lift station.
(9) Wet well control settings must be designed to prevent overloading of downstream pipes and treatment units.
(b) Wet Wells.
(1) A wet well must be enclosed by watertight and gas tight walls.
(2) A penetration through a wall of a wet well must be gas tight.
(3) A wet well must not contain equipment requiring regular or routine inspection or maintenance, unless inspection and maintenance can be done without a person entering the wet well.
(4) A gravity pipe discharging to a wet well must be located so that the invert elevation is above the liquid level of a pump's "on" setting.
(5) Gate valves and check valves are prohibited in a wet well.
(6) Gate valves and check valves may be located in a valve vault next to a wet well or in a dry well. Valve vaults shall be ventilated according to subsection (d) of this section.
(7) A pump must run continuously during the pump cycle time, which begins when the pump is activated by the pump controls. Pump cycle time, based on peak flow, must equal or exceed those in the following table:
(8) An evaluation of minimum wet well volume requires the following formula:
(c) Dry well access.
(1) An underground dry well must be accessible for maintenance and shall be ventilated according to subsection (d) of this section.
(2) A stairway in a dry well must use non-slip steps and conform to Occupational Safety and Health Administration regulations with respect to rise and run.
(3) A ladder in a dry well must be made of non-conductive material and be rated for the load necessary for staff and equipment to descend and ascend.
(d) Lift Station Ventilation.
(1) Passive Ventilation for Wet Wells.
(2) Mechanical Ventilation in Lift Stations.
(e) Wet Well Slopes.
(1) A wet well floor must have a smooth finish and minimum slope of 10% to a pump intake.
(2) A wet well design must prevent deposition of solids, grease, and debris under normal operating conditions.
(3) A lift station with greater than 5.0 million gallons per day firm pumping capacity must have anti-vortex baffling.
(f) Hoisting Equipment. A lift station must have permanent hoisting equipment or be accessible to portable hoisting equipment for removal of pumps, motors, valves, pipes, and other similar equipment.
(g) Valve Vault Drains. A floor drain from a valve vault to a wet well must prevent gas from entering a valve vault by including flap valves, "P" traps, submerged outlets, or a combination of these devices.
(h) Dry Well Sump Pumps.
(1) Pumps.
(2) Pipes.
Source Note: The provisions of this §217.60 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254