Page 140 - Water and wastewater engineering

INTAKE STRUCTURES 3-37

3-2. Design a shore river intake system in a cold climate. Provide the minimum number
of ports. The design conditions are:
3

Winter design flow rate 4,300 m /d
Minimum river elevation held constant by lock and dam system 99.0 m
500-year fl ood elevation 113.3 m
River bottom elevation 90.4 m
Assume a muck bottom
Trash rack: 2 cm diameter; 8 cm between bars
Specify the following:
Number and location of intake ports
Spacing of the ports
Depth of lowest port
Depth of top port
Dimensions of a port
Provide a sketch of the following:
Intake tower with elevations of ports, reservoir elevations, and lake bottom elevation
3-3. Design a conduit to carry water from a submerged intake structure to the wet well of
a low-lift pump station. The design conditions are:
Low water surface elevation 353.5 m
Elevation of lake bottom 306.6 m
Length of pipe from intake structure to wet well 1,500 m
3
Maximum demand at design life 53,000 m /d
Concrete pipe

Assume the lake bottom is flat
Specify the following:
Wet well drawdown elevation
Minimum slope of energy grade line required to carry the maximum demand
Diameter of the conduit
Velocity in the conduit
Depth of soil cover at the intake structure and at the wet well
Provide a sketch showing the following:
Low water surface elevation
Surface elevation of water in the wet well at maximum fl ow rate
Pipe profi le from the intake structure to the low-lift pump station
Elevation of bottom of conduit at the intake structure and at the wet well
Note: Because both the slope of the energy grade line and the diameter are unknown,
a trial and error solution is required. A spreadsheet solution for the trial and error cal-
culation is recommended.
3-4. Design a conduit to carry water from a submerged intake structure to the wet well of
a low-lift pump station. The design conditions are:
Low water surface elevation 153.5 m
Elevation of lake bottom 106.6 m