FLOOD03181

• County: Weld
• Community: Greeley
• Stream Name: Cache La Poudre River
• Basin: South Platte
• Title: Master Floodway Plan
• Date: 8/1/1983
• Prepared For: Greeley, CWCB
• Prepared By: Simons Li & Associates Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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VI. SELECTION OF IMPROVEMENT ALTERNATIVES

Costs of Alternatives

Capital imp~ovement costs were developed for the alternatives and are

presented in Tables 4 'through 7. The costs were developed in order to eval-

uate and compare ~he conceptual designs. Improvement costs have been divided

into the following categories:

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Bridge improvement.

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1.

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2.

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Intake structure relocation.

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3.

Permit development/redevelopment of property within floodplain.

4.

Tax revenue from additional property.

5.

Improved aesthetics.

6.

Reduction of nuisance problems.

7.

Reduced operation and maintenance.

8. Multiple use opportunities.

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Certain advantages and disadvantages are inherent in the different

improvement alternatives. A matrix of advantages and disadvantages for each

alternative is given in Table 9.

Recommended Alternative

The recommended alternative is Alternative 4, a combination of floodway

improvements. The advantages of this alternative are:

3.

Upstream sediment trap.

4.

Flood control alternative.

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5.

Engineering and contingency costs.

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Fiscal, legal, and administrative costs.

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6.

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Land acquisition costs were not included for any alternatives. Bridge

improvements and relocation of the Great Western Sugar Company diversion

structure are common to all alternatives and have been considered as a

separate item. A different unit cost was used for embankment material for

Alternative 2 - Levees. A higher cost was assumed because the embankment

material must be hauled in, while the other alternatives have excess material

available.

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Annual operation and maintenance costs were estimated for the alter-

natives. The estimated annual maintenance costs are $30,800 for improved

levees, $27,300 for the trapezoidal channel, $10,500 for the combination chan-

nel and $11,250 for the combination of floodway improvements. These operation

and maintenance costs include dredging (if necessary) and normal channel main-

tenance costs. Annualized costs were calculated for the alternatives using a

50-year project life and a 7-1/2 percent interest rate. Total annual costs

for the flood control alternatives are summarized in Table 8. These costs do

not reflect the costs of bridge replacement or land acquisition.

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Benefits of Alternatives
Benefits of flood control projects can include the following:

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10.

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1. Flood damage reduction.

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Enhance property values of adjoining property.

2.

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1.

Flooding is controlled for the 100-year event.

2.

Use of levees through the wastewater treatment plant does not
require additional right-of-way.

3.

Development/redevelopment is allowed within the floodplain.

4.

The combination channel is the best hydraulic section for flood
conveyance.

5.

Dredging requirements are reduced and other maintenance requirements
are also reduced.

6.

The combination channel has a positive visual appearance.

7.

The combination channel allows future multiple uses as a greenbelt
or for recreational opportunities.

8.

The combination channel confines low flows to a smaller channel sec-
tion, reducing vegetative growth in the channel, and eliminating
stagnant water.

9.

Property values are enhanced due to more pleasing appearance and
reduced flooding.

This alternative has a lower annual cost than Alternatives 3A and 3B
and is about the same as Alternative 2.