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262 Chapter 7 Water Distribution Systems: Modeling and Computer Applications
Table 7.25 Junction Information for Problem 7.6 6. What do you think are some possible pitfalls of model-
ing two connections to existing mains within the same
Number of system, as opposed to modeling back to the water
Junction Label Lots Serviced
source?
J-1 5 7.7 Use the pipe sizes given in Table 7.27 for the subdivision
J-2 4 in Problem 7.6. City ordinances require that the pressure at the
J-3 4 fire flow discharge and at other points in the distribution system
J-4 5 cannot fall below 125 kPa during a fire flow of 34 L/s. (Hint:
J-5 6 The total flow at the fire flow node does not need to include the
J-6 6 baseline demand.)
J-7 6
Table 7.27 Pipe Information for Problem 7.7
Table 7.26 Pipe Information for Problem 7.6 Pipe Label Diameter (mm)
Pipe Label Length (m) Diameter (mm) P-1 200
P-2 150
P-1 60.0 150 P-3 150
P-2 60.0 150 P-4 150
P-3 110.5 150 P-5 150
P-4 164.0 150 P-6 150
P-5 152.5 150 P-7 150
P-6 204.0 100 P-8 150
P-7 148.0 150 P-9 150
P-8 61.0 100
P-9 194.0 150
1. If a residential fire occurs at J-7, would the current system
be able to meet the fire flow requirements set by the city?
Currently, a model of the entire water system does not
exist. However, hydrant tests were conducted using hydrants lo- 2. If not, what can be done to increase the available flow
cated on two water mains, one in Town Highway #64 and the to provide adequate fire flow to that hydrant?
other in Elm Street. The following data were obtained: 3. If a fire flow is placed at J-4, does the system meet the
requirements with the proposed improvements?
Town Highway #64 Hydrant Test
Without the proposed improvements?
Static pressure: 310.3 kPa
Residual pressure: 98.5 kPa at 32 L/s 7.8 A local water company is concerned with the water qual-
Elevation of pressure gauge: 190 m ity within its water distribution network (Fig. 7.18). They want
to determine the age and the chlorine concentration of the water
Elm Street Hydrant Test
as it exits the system at different junctions. The water surface at
Static pressure: 413.7 kPa
the reservoir is 70 m.
Residual pressure: 319.3 kPa at 40 L/s
Elevation of pressure gauge: 191.5 m
R-1 PMP-1
The subdivision will connect to existing system mains in
P-7
these streets at nodes J-8 and J-9. (Hint: Model the connection P-8 P-13 J-9
to an existing water main with a reservoir and a pump.) J-4 P-4 J-5 P-5 J-6 P-6
J-7
1. What are the demands at each of the junction nodes?
P-1
What is the total demand?
2. Does the present water distribution system have P-10 P-11 P-12
enough capacity to supply the new subdivision?
3. Which connection to the existing main is supplying J-1
more water to the subdivision? Why? P-2 P-14 J-8
J-2
4. Are the proposed pipe sizes adequate to maintain ve- P-3 J-3
P-9
locities between 0.15 m/s and 2.44 m/s, and pressures
of at least 140 kPa?
T-1
5. Would the subdivision have enough water if only one
connection were used? If so, which one? Figure 7.18 Schematic for Problem 7.8