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264 Chapter 7 Water Distribution Systems: Modeling and Computer Applications
7.9 A planning commission has indicated a new industry minimum pressure of 260 kPa will be added to the
may be connected to the water system described in Problem 7.8. system. It could be tapped into the network at either
You are to determine the pipe diameters in the network to junction 6, 7, or 8. Size the pipes for the conditions
minimize the installation cost assuming all the pipes are duc- in part I along with the industry added to all pro-
tile iron. Use the Darwin Designer module to determine the posed junctions. You will need to analyze the net-
total cost and size each pipe for each of the following condi- work three times, once for the industry at J-6, again
tions. Use the pipe cost information from Problem 7.4 for the with the industry at J-7, then finally with the industry
ductile-iron pipe. at J-8.
I. Size the pipes using a demand multiplier (peaking fac- 1. Indicate which option(s) would work best.
tor) of 3.2. The pressure must remain between 170 and 2. Which junction should the industry be tapped into
550 kPa during peak demand. Exclude pipes P-7 and to be the least costly and what is the expected cost?
P-8 in your analysis when determining the pipe sizes.
[Hint: You will need to specify an additional demand 3. What is the size of each pipe for the best solution at
of zero (0 L/min) with the default pressure constraints the least costly option with the industry added?
at the junctions or a fatal error will occur.] 4. What is the calculated minimum pressure at the in-
dustry for the best solution?
II. It is expected that a new industry with an expected
additional demand of 2,000 L/min with a required

BIBLIOGRAPHY
American Water Works Association, Computer Modeling of Haestad Methods, WaterGEMS: Geospatial Water Distribution
Water Distribution Systems, Manual of Water Supply Software, Haestad Press, Waterbury, CT, 2002.
Practices M32, 2nd ed., Denver, CO, 2005. Males, R. M., Grayman, W. M., and Lark, R. M., Modeling
Cesario, A. L., Modeling Analysis and Design of Water Water Quality in Distribution Systems, J. Water Resources
Distribution Systems, American Water Works Association, Planning and Management, 114, 197–209, 1988.
Denver, CO (1995). Rossman, L. A., and Boulos, P. F., Numerical Methods for
Haestad Methods, Advanced Water Distribution Modeling and Modeling Water Quality in Distribution Systems: A
Management, Bentley Institute Press, Exton, PA, 2007. Comparison, J. Water Resources Planning and
Haestad Methods, Computer Applications in Hydraulic Management, 122, 2, 137, 1996.
®
Engineering, 7th ed., Bentley Institute Press, Exton, PA, Walski, T. M., Water System Modeling Using CYBERNET ,
2007. Haestad Press, Waterbury, CT, 1993.