PROJ00121

• Contract/PO #: C153702
• Contractor Name: Silt, Town of
• Contract Type: Loan
• Water District: 39
• County: Garfield
• Bill Number: HB 95-1155
• Loan Projects - Doc Type: Feasibility Study

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Using selected items in the above estimations, Gamba indicated an average daily in-
house demand ranging from 145 to 350 gpd/du,

Gamba estimated irrigation demands by an "Average Monthly Reference Crop
Evapotranspiration Using the FAO Modified Methods" and an assumed irrigated area of
3,500 square feet per dwelling unit. Pennington indicated that this gives an estimate for
crop demand that would tend to be conservatively high, The result is an average daily
irrigation demand during the growing season of about 380 gpd/du, The metered demand
records described above would indicate an average irrigation demand of 483 - 145 = 338
gpd/du which compares favorably with the 380 gpd/du estimate,

Need for the Proiect
Due to growth in population and to capacity limitations in the existing water supply
system, the Town has had to consider options for expanding its water supply capabilities,
The critical factor at present is the treatment capacity of the WTP which is operating at
or near its limit, There are, in addition, concerns with regard to raw water supply in
view of the junior status of the Town's water rights and the need for augmentation water.

The two options considered for water system expansion were:

1, Expand the existing water supply system to include improvements to the

raw water, treatment, and distribution components of the overall system, or

2, Construct a Raw Water Irrigation System (RWIS) to provide non-treated
water for lawn and garden irrigation using existing irrigation ditches and
irrigation water supplies in the vicinity of the Town.

Description of the RWIS
As described in the Gamba report, the proposed Raw Water Irrigation System is a low-
pressure system for delivering untreated irrigation water to each individual water

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