PROJ00224

• Contract/PO #: C153793
• Contractor Name: Buffalo Mutual Irrigation Company
• Contract Type: Loan
• Water District: 67
• County: Prowers
• Bill Number: SB 97-008
• Loan Projects - Doc Type: Feasibility Study

.

s:Mngs over alternative 2. The estimated cost is $326,500 (see explanation on the next
page for methods used to estimate costs).
Constructing an earth dam with an overflow spillway could save as much as
$156,300 over the cost of building a concrete dam across the entire width of the river, The
earth structure is estimated to cost approximately $21,300.

Evaluation of Alternatives:

The following table summarizes the three alternatives considered in this report.
Advantages Disadvantages Capital Costs Ammal Cost
(@4% , 30 years)

---------.------------------------.-..-..----------..----------..--..------..---...---.------......-------........-------....-----------.-....---------..-----------

I, Replace headgale only

Cheapest initial Shorttenn solution. $150,000
cost Dam will cost more
later,

S 8,674

.......-........----...-....-....----.............--......--.............----------.-----.,-..----....--.....------...........-.--------...------............-------...............------.........--

2. Replace headgate and dam. Dam replaced with concrete

Will require least Highest initial cost $482.880
maintenance.

S27,92~

..._...._---------_._---------.........._---------~~.._---------..~..._-----~-~..~_._--------_...._---------~.~_.-------~._.~----------~~.~~~--------~--~~~._----

3. ReplBCe headgate and dam. Dam. half concrete, half earth

Less costly than
Alternative 2,
long teno solution

Earth dBDl_ S326,~00
need replaced fi'om .:t...!Iaill (earlb dam rebuilding)
washonts, S344.89~ S19.94~

.

The capital cost consists of a one tinte cost for construction of the project plus the
present value of foreseeable future costs, not including operation and maintenance.
Operation and maintenance are considered to differ negligibly for the differing alternatives.
For Alternative 1, the capital cost consists of replacing only the headgate. The estimated
future cost of not replacing the dam is an intangible which is discussed later in this section.
For Alternative 2, the capital cost is only the cost of the construction of the dam plus the
headgate, For Alternative 3, the cost is calculated as the cost of the headgate, plus the cost
of the concrete dam, plus the cost of the initial construction of the earth dam, plus the
oresent value of re.placing the earth dam fifteen vears hence and thirtv vears hence usirm
current cost estimates of $21.300 for earth dam construction and a catJitalization rate of
4%,
(Note: The earth dam across the river at the Lamar Canal headgate has been
replaced once in fifteen years, and that replacement was required within one year of the
original construction. The dam was redesigned and an overflow spillway was built when
the dam was reconstructed. If properly engineered, an earth dam should not require
replacement except in the case of a 50-100 year event. For project financial planning, the
assumption of rebuilding the dam twice should provide a reasonable estimate of future
events. )
Annual costs were calculated by applying a capitalization rate of 4% for 30 years.
Although Alternative 1, replacing only the head gate, is the cheapest at an estimated
cost of approximately $150,000 there are rruljor drawbacks to relying on sand dam
construction. The main drawback is the temporary nature of the sand dam, Higher than
nonnal flows causes the dam to wash out. During years of high flow, the number of
washouts could create periods of time that the Buffalo would not be able to divert water at
the times it is needed. In addition, the c\UTent wooden da..To is deteriorating an.d it is like!'! to
wash out. When that happens, the river channel will be subject to scouring which would
w""h "way the .....d in the river olumnel wbi"h io ourrently uaed to oonatruot the .cmd d.un.
The bottom of the river channel upstream from the current dam could be scoured down to

.

9