PROJC00189

• Contract/PO #: C150006
• Contractor Name: Palisade, Town of
• Contract Type: Loan
• Water District: 72
• County: Mesa
• Bill Number: HB 95-1155
• Loan Projects - Doc Type: Feasibility Study

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inexpensive, but heavy and available only in short lengths. Steel pipe is
lightweight, but must be protected from corrosion and requires close
inspection. PVC pipe is frequently used; however, it can only withstand
limited pressures and is more fragile than other types of pipe. Both steel
and PVC require select material for bedding and backfill.

It appears that the most suitable type of pipe for this project will be ductile
iron pipe, mainly because it may be necessary to use natural on-site
materials for bedding and backfill. The ductile iron pipe is capable of
being bedded under more adverse conditions and can withstand rougher
handling. It can also handle higher pressures by using thicker wall pipes.
Its main disadvantage is its moderately heavy weight and greater material
cost. However, this will be offset by cost savings on bedding and backfill,
since they will not have to be imported.

The present plan is to install the new pipe parallel to the existing pipeline.
It will be desirable to keep the old pipe totally in place until the new lines
is installed to provide water to the plant. Because of limited working
room, it may be necessary in some places to remove the existing pipe.

c) Comparison of Pressure Pipe vs Non-Pressnre Pipe Installation The
elevation drop and potential in-line pressures for a pressurized pipeline are
as follows:

Elev. Static
Location ~ Dml1 Pressnre
Cabin Res. Box 7410 ft. 0 0
Wye 5335 ft. 2075 ft. 892 psi
WTP 5010 ft. 2400 ft. 1032 psi

Although equipment will be provided to reduce water hammer, pressure
surges are likely which would increase pressures above those shown. The
high pressures only exist on the pipeline when water is not flowing; when
water is flowing, headloss and velocity head reduce the static head. The
high velocities and high transient pressures will require substantial pipe
restraints for the pressured line installation.

Since the water will be flowing continuously in the non-pressure pipe, the
possibility of freezing is considerably less. Therefore, a burial depth of 3
feet should be adequate. For the pressure pipe, the water may be shut off
for extended periods and a greater burial depth for frost protection is
needed. A 5 foot depth of bury has been selected for the pressure pipe.
In addition, the greater depth will provide greater trench support (to prevent

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