| (a) General Requirements. A raw wastewater pump, with
the exception of a grinder pump, must:
(1) be designed to prevent clogging;
(2) be capable of passing a sphere of 2.5 inches in
diameter or greater; and
(3) have greater than 3.0 inch diameter suction and
discharge openings.
(b) Submersible and Non-submersible Pumps.
(1) A non-submersible pump must have inspection and
cleanout plates on both the suction and discharge sides of each pumping
unit that facilitate locating and removing blockage-causing materials,
unless the pump design accommodates easy removal of the rotation elements.
(2) A pump support for a submersible or non-submersible
pump must prevent movement and vibration during operation.
(3) A submersible pump must use a rail-type pump support
system with manufacturer-approved mechanisms designed to allow personnel
to readily remove and replace any single pump without entering or
dewatering the wet well.
(4) Submersible pump rails and lifting chains must
be constructed of a material that performs to at least the standard
of Series 300 stainless steel.
(5) All lift station pumps and associated appurtenances
must be designed to prevent the discharge of wastewater from the lift
station and at all points in the upstream collection system.
(c) Lift Station Pumping Capacity. A lift station must
have at least two pumps. The firm pumping capacity of a lift station
must handle the peak flow.
(d) Pump Head Calculations.
(1) An owner must select a pump based upon analysis
of the system head and pump capacity curves. The owner must determine
the pumping capacities and pressure head requirements of a single
pump operating alone, and with other pumps.
(2) The engineering report must include pipe head loss
calculations, using the American National Standards Institute's Hydraulic
Institute Standards pertaining to head losses through pipes, valves,
and fittings.
(3) The engineering report must include the friction
coefficient (Hazen-Williams "C" value) used in friction head loss
calculations. The selected friction coefficient must be based on the
pipe material.
(4) For a lift station with more than two pumps, a
force main in excess of one-half mile, or a lift station with a firm
pumping capacity of 100 gallons per minute or greater, the engineering
report must include system curves for both the normal and peak operating
conditions at friction coefficient values (C values) for the force
main pipe.
(e) Flow Control.
(1) A lift station or a transfer pumping station located
at or discharging directly to a wastewater treatment facility must
have a peak pump capacity equal to or less than the peak flow, unless
equalization is provided.
(2) Each lift station or transfer pumping station located
at or discharging directly to a wastewater treatment facility with
a peak flow that is greater than 300,000 gallons per day must use
three or more pumps, unless duplex, automatically controlled, variable
capacity pumps are used.
(3) Each lift station or transfer pumping station located
at or discharging directly to a wastewater treatment facility with
a peak flow that is less than or equal to 300,000 gallons per day
must use at least two pumps.
(f) Self-Priming Pumps.
(1) A self-priming pump must be capable of priming
without relying on a separate priming system, an internal flap valve,
or any other external method for priming.
(2) A self-priming pump must use a suction pipe that
produces flow with velocity of at least 3.0 feet per second but not
more than 7.0 feet per second. A self-priming pump must have its own
suction pipe.
(3) A self-priming pump must vent air back into the
wet well during priming.
(g) Vacuum-Priming Pumps.
(1) A vacuum-primed pump must be capable of priming
by using a separate positive priming system with a dedicated vacuum
pump for each main wastewater pump.
(2) A vacuum-priming pump must produce a suction pipe
velocity between 3.0 and 7.0 feet per second. A vacuum priming pump
must have its own suction pipe.
(h) Vertical Positioning of Pumps. A raw wastewater
pump must maintain positive static suction head during normal on-off
cycling. A submersible pump with "no suction" pipes, a vacuum-primed
pump, or a self-priming unit capable of satisfactory operation under
any negative suction head anticipated for the lift station is not
required to have positive static suction head during normal on-off
cycling.
(i) Individual Grinder Pumps. A grinder pump is not
subject to the requirements of this subchapter if:
(1) the grinder pump is not part of an alternative
collection system as defined by this chapter; and
(2) the grinder pump only serves a single connection
to a wastewater collection system.
(j) Pump for Low-Flow Lift Station. A pump used for
a lift station with a peak flow of less than 120 gallons per minute
must be submersible and include a grinder.
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