3 August 1998
d. Ventilation. Where a gravity ventilation system is deemed inadequate to supply fresh air
and remove fumes and heated air from the pump station, a forced ventilation system should be
provided. The ventilation system should be capable of removing waste heat from the motors
without allowing more than a 6o K (10o F) rise in the temperature of the air in the pump station.
For occupied areas, the ventilation system will have a capacity of about six air changes per
hour. If dust-producing chemicals are to be handled at the station, special dust exhaust
systems will also be provided. Where chemicals are used in the pump station, precautions
should be taken to ensure that the exhaust from the ventilation system complies with air
e. Pumping equipment. In general, pumping equipment shall be sized to conform to
the rated capacity of the water treatment plant and will include a minimum of three electric
motor driven pumps. With the largest of the three pumps out of service, the remaining two
pumps will be capable of supplying raw water at a rate equal to the rated capacity of the plant.
To ensure water service in the event of a major power outage, a sufficient number of pumps
must be equipped for operation when normal electric power is not available. These pumps will
be capable of supplying at least 50 percent of the rated capacity of the treatment plant, except
where greater capacity is essential. Standby power for emergency operation can be provided
by gas-turbine or diesel engine generators or by engines arranged to provide for pump
operation by direct engine drives during the emergency.
8-2. GROUND WATER SOURCES. For most applications, either vertical line shaft turbine
pumps or submersible turbine pumps will be used. For small capacity or low-head
applications, rotary or reciprocating (piston) pumps may be more appropriate. Factors
influencing the selection of pumping equipment include well size, maximum pumping rate,
range in pumping rate, maximum total head requirements, range in total head requirements,
and type of power available. Final selection of pumping equipment will be based on life cycle
cost considerations. If all pumps use electric power as the primary energy source, a sufficient
number of the pumps must be equipped for emergency operation when normal electric power
is not available. Emergency power can be provided by gas-turbine or diesel engine generators
or by engines arranged to provide for pump operation by direct engine drives during the
emergency. These standby-powered pumps will be capable of supplying at least 50 percent of
the required daily demand, except where greater capacity is essential.
8-3. ELECTRIC POWER. If dual electric power feeders, breakers, transformers and
switchgear can be provided, they will increase the station's reliability but may add appreciably
to its cost. If a high degree of reliability is deemed necessary, the station should be served by
independent transmission lines that are connected to independent power sources or have
automatic switch over to direct drive engines.
8-4. CONTROL OF PUMPING FACILITIES. Supervisory or remote control of electric
motor-driven pumping units will be provided if such control will substantially reduce operator
time at the facilities. Life cycle cost will apply.