TM 5-814-2/AFM 88-11, Vol. 2
CHAPTER 3
TYPE AND CAPACITY OF PUMPING STATIONS
mode of operation will normally require two or more
Required pumping capacity. Proper selection
3-1.
wastewater pumps of the constant or variable speed
of the number and capacity of pumping units is
type, operating in single or multiple pump combinations,
dependent upon the quantity and variation of
as required to match the incoming flowrates.
wastewater flows to be handled. Except as indicated
below for small stations, pumping units will be selected
Type of construction.
A classification of
to handle the normal daily range of wastewater flows
3-2.
pumping stations by capacity and the method of
generated in the service area.
The number and
construction normally utilized for that capacity is
capacity of pumps provided will be sufficient to
provided in Table 3-1. Factory assembled pumping
discharge the minimum, average, peak daily and
stations, commonly referred to as package type stations,
extreme peak flowrates as calculated in TM 5-814-
are manufactured in standard sizes and are shipped
1/AFM 88-11, Vol. 1. Pumping capacity will be
from the factory in modules with all equipment and
adequate to discharge the peak flowrates with the
components mounted, installed, and ready for
largest pump out of service.
Pumps utilized for
connection. These type stations will be suitable for low
treatment plant processes, recycling and bypassing of
flows, and where the need to protect pumps from
flows, etc., will be based on criteria developed in TM 5-
clogging is minimal.
Conventional field erected
8143/AFM 88-11, Vol. 3. Consideration will be given to
pumping stations are designed for a particular location
future conditions which may occur during the life of the
and to meet specific requirements. Field constructed
station.
Normally, where future development and
stations will be used where the quantity of flow or its
population increases are projected for the area, pumps
variation, or both, exceeds the capacity of available
will be designed for initial conditions only, and the
factory assembled stations, or where site conditions
station will be provided adequate room for expansion of
require the use of special designs or construction
pumping capacity at a later date. Expansion of pumping
methods.
capacity can be accomplished with the installation of
additional pumping units, larger pumps, impellers, drive
units, adjustable or variable speed drives. However,
Table 3-1. Classification of pumping stations.
some situations may warrant provision of capacity for
future increases initially, for economic or other reasons.
Recommended
Each case will be analyzed individually.
Capacity
a. Small stations. Pumping stations required for
Range Class/Type
Gallons Per Minute
small remote areas which generate extreme peak
Factory Assembled (Package
flowrates of less than 700 gpm, and where the possibility
Type)
of future expansion is unlikely, and grinder pump
Pneumatic Ejectors
30-200
installations serving three or more buildings, will be
Wet Pit Submersible
100-500
provided with two identical pumping units.
Each
Pumps
pumping unit will be of the constant speed type, and will
Dry Pit Pumps
100-2,000
be capable of discharging the extreme peak wastewater
Conventional Field Erected
flowrate. The station will be designed to alternate
Small
300-1,500
between zero discharge and peak discharge. This
Intermediate
1,500-10,000
arrangement will provide 100 percent standby capacity
Large
over 10,000
to allow for necessary maintenance and repairs.
Note: Package type, dry pit pump stations in the
Pneumatic ejector stations will be provided with duplex
capacities shown are generally available off-the-
ejectors each sized for the extreme peak flowrate.
shelf. However, station capacities up to 5,000
b. Large stations. Pumping stations serving large
gallons per minute can be obtained by special
areas of the installation, and especially stations where
order.
the entire wastewater flow or major portions thereof
must be pumped to the treatment facility, will be
designed so far as practicable to operate on a
continuous basis. The rate of pumpage must change in
increments as the inflow to the station varies. This
3-1
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