Section 217.60 - Lift Station, Wet Well, and Dry Well Designs(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: Attached Graphic
(8) An evaluation of minimum wet well volume requires the following formula: Attached Graphic
(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. (A) Passive ventilation structures must include screening to prevent the entry of birds and insects to a wet well. The screening must be made of corrosion-resistant material.(B) All mechanical and electrical equipment in a wet well with passive ventilation must be constructed in compliance with explosion requirements in the National Fire Protection Association 70 National Electrical Code®.(C) A passive ventilation system must be sized to vent at a rate equal to the maximum pumping rate of a lift station, but not to exceed 600 feet per minute through a vent pipe.(D) The minimum acceptable diameter for an air vent is 4.0 inches.(E) All vent outlets must be at least 1.0 foot above a 100-year flood plain elevation.(2) Mechanical Ventilation in Lift Stations. (A) Dry Wells. (i) A dry well must use mechanical ventilation.(ii) Ventilation equipment under continuous operation must have a minimum capacity of six complete air exchanges per hour.(iii) Ventilation equipment under intermittent operations must provide a minimum capacity of 30 complete air exchanges per hour and be connected to the lift station's lighting system.(B) Wet Wells. (i) Mechanical ventilation systems for wet wells must operate continuously.(ii) The ventilation equipment must provide at least 12 complete air exchanges per hour and be constructed of corrosion-resistant material.(iii) An owner shall implement odor control measures necessary to prevent a wet well from becoming a nuisance. An owner shall consider the source of potential odor, turbulence, residence time, and other factors that contribute odor at a lift station when selecting odor control measures.(iv) All mechanical and electrical equipment in a wet well with mechanical ventilation must be constructed in compliance with explosion requirements in National Fire Protection Association 70 National Electrical Code®.(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. (A) A dry well must use dual sump pumps, each with a minimum capacity of 1,000 gallons per hour and capable of handling the volume of liquid necessary to prevent accumulation of water from condensation and incidental leaks during peak pumping operations.(B) A sump pump must have a submersible motor and watertight wiring.(C) A dry well floor must slope toward the sump. A sump must include sump pumps sized to prevent accumulation of water from condensation and incidental leaks.(D) The minimum sump depth is 6.0 inches. The sump must prevent standing water from accumulating on a dry well floor under normal operation.(E) A sump pump must operate automatically by use of a float switch or another level-detecting device.(2) Pipes. (A) A sump pump must use independent piping that is capable of discharging more than the maximum liquid level of an associated wet well at a rate that will prevent overflow of the wet well.(B) A sump pump outlet pipe must be at least 1.5 inches in diameter and have at least two check valves in series.30 Tex. Admin. Code § 217.60
The provisions of this §217.60 adopted to be effective August 28, 2008, 33 TexReg 6843; Amended by Texas Register, Volume 40, Number 47, November 20, 2015, TexReg 8307, eff. 12/4/2015