PROJ00156

• Contract/PO #: C153721
• Contractor Name: Lyons, Town of
• Contract Type: Loan
• Water District: 5
• County: Boulder
• Loan Projects - Doc Type: Feasibility Study

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roughness factor was than adjusted to calibrate the model. It was found that the older pipes in
the system (approximately 50 years old) required that the roughness factor be reduced to 60.
this indicated that the older portion of the existing system has sever tuberculation.

Results of the computer analysis are as follows:

l.The existing system currently has the ability to meet maximum daily flows.

a.Pressures
(1) Upper pressure zone - 63 psi to 128 psi
(2) Lower pressure zone - 43 psi to 100 psi

2.Fire flows
a. A fire flow of 1000 g.p.m. (as directed by the town) + maximum day demand was
used at a residual pressure of 20 psi at the hydrant.
b. The 0.35 MG in-town storage tank was turned off in model, because a fire might
occur when the tank was not operating.
c.Significant problems with fire flows are apparent.

(1) Large portions of the upper zone can not meet the required 1000 g.p.m.. In
the northeast part of town at the highest hydrant, maximum available fire flow
available is 657 g.p.m. in Longs Peak Drive (fire hydrant elevation 5535) with
a residual pressure of 20 psL This low flow is most notably due to the losses in
the six and 8 inch pipes. It is probable that there are actually negative pressures
in the higher portions of the zone under fire demand conditions.

(2) The lower zone has large areas where the maximum fire flow is less than the
required 1000 g.p.m.. The deficiency occurs primarily in the older parts of
town. The minimum available fire flow was 232 g.p.m. located on Ewald
A venue. these low flows are due to the small diameter of pipes (typically 4
inches or less) and the age of the system (high tuberculation).

Refer to Figure 6 which shows the apparent problem areas. In summary, results suggest that
while the existing system is capable of delivering at least 40 psi throughout most of the system
during the peak hour demand, it was found that sufficient fire flows could not be maintained at
all hydrants in the system. Specifically, in the upper pressure zone not all of the fire hydrants
are able to deliver the required fire flows at the required pressure. This is due in part to the
single feed to this zone and the six inch pipes within the system.

Additionally, head loss tends to be a problem in water distribution systems when pipe
diameters of less than six inches are used. In particular, small diameter pipes incur excessive
head loss rates when carrying fire flows. One way to treat this problem is to "loop" water
lines in a system. By constructing or modifying a system to be composed of several

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