Page 139 - Water and wastewater engineering

3-36 WATER AND WASTEWATER ENGINEERING

3. Select the appropriate screen type (coarse or fine) for a given scenario, that is, place-
ment in the intake structure or type of material to be removed.
4. Select the appropriate type of pump from a pump catalog for a deep low-lift pump station.
5. Explain the advantages and disadvantages of an adjustable frequency drive for a pump
to a client.
6. Explain, to a client, what frazil ice is and how its buildup on the intake structure may
be minimized.
7. Explain, to a news media person, why zebra mussels are an operational problem and
list two control techniques.
With the use of this text, you should be able to do the following:
8. For a given scenario (river or lake) with appropriate data on depth, sediment, and cli-
mate, select an acceptable type of intake structure.
9. Design an intake port given the seasonal flow rates and climate conditions.
10. Design a bar rack for an intake port given the seasonal flow rates and climate conditions.
11. Design the conduit to carry water from an offshore intake structure to a low-lift pump station.
12. Construct a system head curve given the elevations, pipe dimensions, and identification
of the fittings.
13. Given a system head curve and a set of head-discharge curves, select an appropriate
pump and specify (1) BEP, (2) number of stages, (3) efficiency at BEP, (4) the operat-
ing range of flow rate, and (5) motor power.
14. Design the wet well for a low-lift pump station including specifications of (1) the depth
of the wet well and (2) the location of the pump intake given the surface water level,
intake conduit specifications, and pump NPSH.

3-7 PROBLEMS

3-1. Design a tower intake to be placed in a reservoir in a warm climate. Provide the mini-
mum number of ports. The design conditions are:
3
Summer design flow rate 38,000 m /d

Maximum reservoir elevation 499.0 m
Minimum reservoir elevation 480.7 m
Lake bottom elevation 477.7 m
Bar rack bars: 1 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