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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3.

Improved river crossings at 8th Street. 5th Street. and 6th Avenue

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5.

Combination channel.

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Advantages

Disadvantaqes

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Advantages

Disadvantages

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Reduces' disruption of
transportation during
flooding.

Does not eliminate flooding
problems for the majority of
the study area.

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Eliminates flooding prob-
lems for 100-year recurrence
interval or less.

Requires 300 feet of
right-of-way.

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Reduces water surface
elevations during flooding
in the vicinity of
bridges.

Does not solve sedimentation
problems.

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Allows development to
edge of channel.

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Requires no right-of-way
acquisition.

Requires continued dredging.

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Provides future multiple use
opportunities in the form of
greenbelt or a recreational
trail.

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4a. Trapezoidal channelization (100-year design flow).

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6.

Dredging to increase flow area.

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Advantages

Disadvantaqes

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Advantages

Disadvantages

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Eliminates flooding prob-
lems for 100-year recurrence
intervals or less.

Limited multiple use
opportunities.

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No right-of-way
acquisition required.

Does not eliminate flooding
problems.

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Allows development of
property adjacent to river.

Requires continued dredging.

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Lowers water surface
elevation and groundwater
table at some locations.

Requires continued annual
dredging.

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Requires only 230 feet of
right-of-way.

Meandering low-flow channel may
develop causing bank instability.

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May cause bank instability.

Advantages

Disadvantaqes

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May lower bridge pier capacity
and/or create possibilities of
piers being washed out.

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4b.

Trapezoidal channelization (50-year design flOW).

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Eliminates flooding prob-
lems for the 50-year
recurrence interval or
less.

Flooding problems for 100-year
recurrence interval not
eliminated.

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Five alternatives were selected for further evaluation. These are:

1. Maintain existing condition.

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Reduces floodway width,
allowing some development.

Requires continued dredging.

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2. Improved flood control levees.

3a. Trapezoidal channel.

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Requires only 200 feet of
right-of-way.

Limited multiple use
opportunities.

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3b. Combination channel.

Meandering lOW-flow channel may
develop causing bank instability.

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4. Combinations of improvements.

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Improved river crossings at 8th Street, 5th Street, and 6th Avenue do not

by themselves solve flooding problems, but are required in alternatives 2, 3a,

3b and 4 as part of the total flood control improvement alternative. Bridges

at 8th Street and 5th Street require replacement or enlargement. Since 8th

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