Four Corner - Texas Water Development Board

for greater distances between lift stations while minimizing the number of lift stations
and the depth of gravity sewers.
Wet well dimensions will vary with each lift/pump station and with the phase of
construction being considered. The diameter of the wet well must accommodate the
number of pumps needed to handle the design flow while maintaining adequate clearance
between each pump. Wet well volume is a function of flow rate and pump cycle time.
Minimum allowable cycle time is 6 minutes from start to start. The size of pumps
required varies from ~2 hp to ~45 hp.
Due to the distance between the service area and the source of wastewater treatment, a
pump station and force main will be needed to serve Area I. The flows for the pump/ lift
station for Area I vary substantially from initial to ultimate conditions. This station
should be designed with two pumps for the initial conditions and will ultimately require
three pumps to meet future conditions. The wet well should be large enough to allow for
a third pump to be added as future demands warrant it. At that time, two pumps will
handle the design flow, and the third will operate as a backup.
The lift stations, which are significantly smaller than the pump station, reqmre
installation of only two pumps for operation. Lift station pumps should be selected such
that a single pump can handle the design flow allowing the second pump to serve as
backup. The lift stations for Area 2 and 3 should be designed to transition from initial to
ultimate flows, if necessary, by pump modifications.
WATER DISTRIBUTION SYSTEM
In addition to hydraulic and pressure considerations, the following design criteria was
applied to sizing the water distribution system.
Diameter
4-inch
Design Limitations
Only on dead-end lines within cui-de-sacs supplying maxrmum of I6
connections.
Four Corners Area Water and Wastewater Facilities Planning Study
Page 5-4
FINAL REPORT
Revised 2/10/99