1. (a) Pump Controls.

   1. (1) A lift station pump must operate automatically, based on the water level in a wet well.
   2. (2) The location of a wet well level mechanism must ensure that the mechanism is unaffected by currents, rags, grease, or other floating materials.
   3. (3) A level mechanism must be accessible without entering the wet well.
   4. (4) Wet well controls with a bubbler system require dual air supply and dual controls.
   5. (5) Motor control centers must be mounted at least 4.0 inches above grade to prevent water intrusion and corrosion from standing water in the enclosure.
   6. (6) Electrical equipment and electrical connections in a wet well or a dry well must meet National Fire Prevention Association 70 National Electric Code explosion prevention requirements, unless continuous ventilation is provided.

2. (b) Wet Wells.

   1. (1) A wet well must be enclosed by watertight and gas tight walls.
   2. (2) A penetration through a wall of a wet well must be gas tight.
   3. (3) A wet well must not contain equipment requiring regular or routine inspection or maintenance, unless inspection and maintenance can be done without staff entering the wet well.
   4. (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. (5) Gate valves and check valves are prohibited in a wet well.
   6. (6) Gate valves and check valves may be located in a valve vault next to a wet well or in a dry well.
   7. (7) Pump cycle time, based on peak flow, must equal or exceed those in the following table:
      Attached Graphic
      
   8. (8) An evaluation of minimum wet well volume requires the following formula:
      Attached Graphic
      

3. (c) Dry well access.

   1. (1) An underground dry well must be accessible.
   2. (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. (3) A ladder in a dry well must made of non-conductive material and rated for the load necessary for staff and equipment to descend and ascend.

4. (d) Lift Station Ventilation.

   1. (1) Passive Ventilation for Wet Wells.

      1. (A) Passive ventilation structures must include screening to prevent the entry of birds and insects to a wet well.
      2. (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 Electric Code.
      3. (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.
      4. (D) The minimum acceptable diameter for an air vent is 4.0 inches.
      5. (E) A vent outlet must be at least 1.0 foot above a 100-year flood plain elevation.

   2. (2) Mechanical Ventilation in Lift Stations.

      1. (A) Dry Wells.

         1. (i) A dry well must use mechanical ventilation.
         2. (ii) Ventilation equipment under continuous operation must have a minimum capacity of six air exchanges per hour.
         3. (iii) Ventilation equipment under intermittent operations must have a minimum capacity of 30 air exchanges per hour and be connected to a lift station's lighting system.

      2. (B) Wet Wells.

         1. (i) A wet well must use continuous mechanical ventilation.
         2. (ii) The ventilation equipment must have a minimum capacity of 12 air exchanges per hour and be constructed of corrosion resistant material.
         3. (iii) The design of a wet well must reduce odor potential in a populated area.

5. (e) Wet Well Slopes.

   1. (1) A wet well floor must have a smooth finish and minimum slope of 10% to a pump intake.
   2. (2) A wet well design must prevent deposition of solids under normal operating conditions.
   3. (3) A lift station with greater than 5.0 million gallons per day firm pumping capacity must have anti-vortex baffling.
6. (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.
7. (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.

8. (h) Dry Well Sump Pumps.

   1. (1) Pumps.

      1. (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 generated during peak operations.
      2. (B) A pump must have a submersible motor and watertight wiring.
      3. (C) A dry well floor must slope toward a sump sized for proper drainage.
      4. (D) The minimum sump depth is 6.0 inches and must prevent standing water on a dry well floor under normal operation.
      5. (E) A sump pump must operate automatically by use of a float switch or other level-detecting device.

   2. (2) Pipes.

      1. (A) A sump pump must use separate pipes capable of discharging more than the maximum liquid level of an associated wet well.
      2. (B) A sump pump outlet pipe must be at least 1.5 inches in diameter and have at least two check valves in series.

Source Note:The provisions of this §217.60 adopted to be effective August 28, 2008, 33 TexReg 6843.