PROJ02008

• Contract/PO #: FS0073FX
• Contractor Name: Lamar, City of
• Contract Type: Grant
• Water District: 0
• Loan Projects - Doc Type: Feasibility Study

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Service Area and Water Requirements

Several assumptions were made to determine the anticipated water use requirements
and overall sizing of the pump stations, storage facilities, and pipelines. One assumption
is the actual irrigated area to be served by the system. The irrigation water requirements
within the City of Lamar vary depending on the type of property that is being served. For
the purpose of this study, four main Water Use Classifications for properties within the
overall secondary supply system have been identified; Single family residential
properties, Non-Single family residential properties, Institutional and Parks properties,
and Commercial and Industrial properties. The following assumptions were made
regarding peak season irrigation scheduling parameters and irrigated area or flow
demand for each of the four classifications:

· Single Family Residential (SFR); Irrigated on odd/even schedule (3 days per
week), 10 GPM flow demand per lot
· Non-Single Family Residential (NSFR); 7-day schedule, 8-hour water window,
30% of overall lot area is irrigated
· Institutional and Parks (IN/PK); 7-day schedule, 8-hour water window, 95% of
overall lot area is irrigated
· Commercial and Industrial (CM/IND); 7-day schedule, 8-hour water window, 30%
of overall lot area is irrigated

Irrigation water requirements were calculated using bluegrass turf as the typical plant
material to be irrigated. The peak season daily water requirement was determined based
on an evaluation of historical weather station data reported between 1999 and 2003 from
the LAM01 Weather Station, located 4.5 miles south of the City of Lamar, within the
Colorado State University CoAgMet monitoring system. It was determined from this data
that the average peak season daily Reference Evapotranspiration Rate (ET 0) is
0.43"/day, and the average peak season daily Effective Rainfall is O.03"/day. Using a
crop coefficient of 80% for bluegrass turf and an estimated irrigation system
management efficiency of 80%, it was determined that the daily irrigation application rate
in the City of Lamar area is approximately 0.44"/day during the peak irrigation season.

Based on the CoAgMet data, the seasonal irrigation requirement for bluegrass turf in
Lamar is estimated to be 47-inches per year. This seasonal requirement allows for some
variation depending on the desired appearance of the turf and the use of the area. For
example, lower visibility areas or areas that utilize more drought tolerant plant material
may survive on less water, while high visibility areas and sites that have a high degree of
use such as the golf course or sports fields may require slightly more water to maintain
the desired appearance. For the purpose of this report, the 47 -inch per year figure was
used for all sites.

In order to effectively size the pumping stations, water storage facilities and secondary
supply piping network, it is necessary to conceptualize how the water demands will be
distributed throughout the system. To evaluate the system demand distribution as part of
this study, the City has been divided into fifteen Water Use Demand Zones (Figure 6).
The anticipated water use for each demand zone has been evaluated based on the
estimated water application requirements and the Water Use Classification areas within
each Water Use Demand Zone. Spread sheets were developed to determine the

Aqua Engineering, Inc.
and Colorado State University
May 19, 2004

Secondary Supply Feasibility Study
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