Texas Administrative Code › Title 30 - ENVIRONMENTAL QUALITY › Part 1 - TEXAS COMMISSION ON ENVIRONMENTAL QUALITY › Chapter 317 - DESIGN CRITERIA PRIOR TO 2008 › Section 317.3 - Lift Stations

Current through Reg. 49, No. 28; July 12, 2024
(a) Site selection.
				In the selection of a site for a lift station, consideration shall be given to
				accessibility and potential nuisance aspects. The station shall be protected
				from the 100-year flood and shall be accessible during a 25-year flood. All
				lift stations shall be intruder-resistant with a controlled access. Lift
				stations should be located as remotely as possible from populated
				areas.
(b) Design.
(1) Small lift stations. Lift stations
				designed for a discharge capacity of less than 100 gallons per minute will be
				reviewed on a case-by-case basis by the commission and shall be used only for
				institutional use or other locations where it is necessary to pump the sewage
				from a single building, school, or other measurable source establishment into
				the sanitary sewer lines. If the location of the discharge does not provide a
				positive head due to elevation, then a positive pressure control valve shall be
				provided. Ejectors may be used for this type of lift station. Whenever a lift
				station handles waste from two or more residential housing units, or from any
				public establishment, standby pumps shall be provided. In the case of ejectors
				or eductors, two air compressors shall be provided. Grinder pumps should be
				used for all small installations.
(2) Dry well sump pump. The following design
				considerations shall be addressed in providing dry well sump pumps.
(A) Two separate sump pumps should be
				provided for removal of leakage or water from the dry well floor.
(B) The discharge pipe level from the sump
				pumps shall be above the maximum liquid level of the wet well. A check valve
				should be installed on the discharge side of each sump pump.
(C) All floor and walkway surfaces shall have
				an adequate slope to a point of drainage with sufficient measures taken to
				maximize traction and safety.
(D)
				Motors to drive sump pumps shall be located above the height of the maximum
				liquid level in the wet well. As an alternate, sump pumps may be of the
				submersible type.
(3)
				Pump controls. All lift stations shall have automatically operated pump control
				mechanisms. Pump control mechanisms shall be located so that they will not be
				affected by flow currents in the wet well. Provisions shall be made to prevent
				grease and other floating materials and rags in the wet well from interfering
				with the operation of the controls. When a float tube is located in the dry
				well, its height shall be such as to prevent overflow of the sewage into the
				dry well. Pump control mechanisms which depend on a bubbler in the wet well
				shall be equipped with a backup air supply system. All connections to level
				controls in the wet well shall be accessible at all times. The circuit
				breakers, indicator lights, pump control switches, and other electrical
				equipment should be located on a control panel at least three feet above ground
				surface elevation. If controls are located in a dry well, the dry well shall be
				protected from flooding.
(4) Wet
				wells.
(A) Wet wells and dry wells, including
				their superstructure, shall be separated by at least a watertight and gastight
				wall with separate lockable entrances provided to each. Equipment requiring
				regular or routine inspection and maintenance shall not be located in the wet
				well, unless the maintenance can be accomplished without entering the wet
				well.
(B) Based on design flow, wet
				well capacity should provide a pump cycle time of not less than six minutes for
				those lift stations using submersible pumps and not less than 10 minutes for
				other nonsubmersible pump lift stations.
(C) All influent gravity lines into a wet
				well shall be located where the invert is above the "off" setting liquid level
				of the pumps, and preferably should be located above the lead pump "on"
				setting.
(5) Stairways.
				Stairways with non-slip steps shall be provided in all underground dry wells.
				Removable ladders may be provided in small stations where it is impractical to
				install stairways.
(6) Ventilation.
				Ventilation shall be provided for lift stations, including both wet and dry
				wells.
(A) Passive ventilation such as
				gooseneck type or turbine ventilators designed to prevent possible entry of
				insects or birds shall be provided in all wet wells if mechanical ventilation
				is not provided. All mechanical and electrical equipment in wet wells should be
				explosion-proof and spark-proof construction if mechanical ventilation is not
				provided.
(B) Mechanical
				ventilation shall be provided for all dry wells below the ground surface. The
				ventilation equipment shall have a minimum capacity of six air changes per hour
				under continuous operations. At least a capacity of 30 air changes per hour
				shall be required where the operation is intermittent. All intermittently
				operated venting equipment shall be interconnected with the stations lighting
				system.
(7) Wet well
				slopes. The bottom of wet wells shall have a minimum slope of 10% to the pump
				intakes and shall have a smooth finish. There shall be no projections in the
				wet well which will allow deposition of solids under ordinary operating
				conditions. Antivortex baffling should be considered for the pump suctions in
				all large sewage pumping stations (greater than five million gallons per day
				(mgd) firm pumping capacity).
(8)
				Hoisting equipment. Hoisting equipment or access by hoisting equipment for the
				removal of pumps, motors, valves, etc., shall be incorporated in the station
				design.
(9) Dry wells and valve
				vault drains. Drains from dry wells or valve vaults to the wet well shall be
				equipped with suitable devices to prevent entry of potentially hazardous
				gases.