PROJ00061

• Contract/PO #: C153366
• Contractor Name: Ridges Metropolitan District
• Contract Type: Loan
• Water District: 72
• County: Mesa
• Bill Number: SB 81-439
• Loan Projects - Doc Type: Feasibility Study

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Inasmuch as the service area will be primarily residential in nature with
limited commercial and no industrial use, 40% of 150, or 60 gpcd could be
considered realistic, especially in view of the fact that a separate sys-
tem for the supply and distribution of irrigation water is planned.

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Ute Water records support this assumption by indicating an average of 6000
gal/dwelling unit/month or 57 gpcd (inside the home usage only).

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It is necessary, in sizing water mains, to consider the maximum usage at any
one time. Past records from other water users substantiate the fact that a
water consumer will use, on a maximum day, fifty per cent more water than on
an average day. Moreover, during the peak hour of the maximum day rate, he
will use water at the rate of 175 per cent of the maximum day rate. There-
fore, the rate of water consumption on the maximum date becomes 60 x 1.50 =
90 gpcd and the rate of consumption during the maximum hour of that day be-
comes 90 x 1.75 = 158 gpcd, say 160 gpcd. The usage rate figure of 160 gal-
lons per capita day must be used as a basis of design in order to assure ade-
quate distribution of water during periods of peak demands.

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A residence should be supplied with a flow of ten gallons per minute with a
residual pressure of ten pounds per square inch to insure proper operation
of all normal plumbing fixtures. A pressure of twenty-five pounds per square
inch in the water mains should be provided to insure a minimum of ten pounds
per square inch at the tap. Actual pressures in the Ridges system, however,
are not likely to fall below 40-50 psi due to the high pressure (180-190 psi)
in the supply line. On the contrary, pressure reducing valves will be re-
quired in the lower portions of the system where main line pressures are in
excess of 125 psi.

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The distribution system and approximate pipe sizes are shown on Figure 2-B.

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The cost of the water system proposed herein includes providing a 3/4-inch
service line and meter to each individual single family lot, and up to a
4-inch service line and meter to individual buildings within multi-family
clusters.

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In order to maintain an adequate supply of water in the event of a break in
the main distribution line, storage of one average day's demand should be
provided. For a population of 10,500, the requirement would be 630,000 gal-
lons. A single tank of at least this capacity will be constructed at the
highest elevation in the service area, or a secondary supply line will be pro-
vided per contract with Ute Water.

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Water distribution lines will be installed at a depth of four feet to protect
against freezing. Water lines will be constructed of suitable materials
such as cast iron or asbestos-cement, capable of withstanding design pressures.
Fire hydrants, valves and fittings will be of the types approved by the
American Water Works Association. The proposed storage tank will be concrete
or steel, if constructed.

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Recreation. The general development plan reflects a complimentary re-

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