FLOOD01211

• County: Pueblo
• Community: Pueblo
• Stream Name: Fountain Creek
• Title: Pueblo Flood Control Project
• Date: 1/1/1990
• Prepared For: Pueblo County
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Project

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due to its steeper side slopes, thus requ1r1ng no additional excavation due to
lost capacity. Soil cement levees used in Tucson, Arizona, have performed
very well under velocities in the range of 20-25 fps. The highest velocity in
the soil cement reach at Fountain Creek is 12.5 fps. A combination levee
consisting of a 390-foot long flood wall, and 337-foot soil-cement section is
required from Station 1+73W to Station 9+00W on the west side of Fountain
Creek due to space restrictions between the railroad and highway
right-of-ways. Adequate space allows an earthen levee section from Station
9+00W to Station 15+00W.

3-17. Freeboard and Protective Measures. The greatest discharge for which
damage prevention is claimed is 99,400 cfs, which corresponds to approximately
the 250 year flood. All elemenuor-tne des ign channel perform satisfactorily
up to this discharge. The location of the critical section is in the-':
"constricted" flow area, approximately 1,600 feet downstream of the 4th Street
bridge. Another section, approximately 100 feet upstream of the AT&SF bridge,
has a capacity of 101,400 cfs. All other elements of the design channel have
a capacity greater than 105,000 cfs.

3-18. A SOD-foot section located at the do~nstream end of the project,
immediately upstream of the Missouri Pacif"c Railroad bridge, provides 2-feet
of freeboard. This reduced freeboard section was provided to assure the least
hazardous (damaging) initial overtopping location. However, there is a
disproportionate amount of increase in the water surface elevation upstream of
the bridges (especially at AT&SF, 4th Street and 8th Street) as compared to
the downstream end of the project. A 2-foot increase above the design water
surface at the downstream end of the project yields increases of 10 feet, 6
feet, and 6 feet On the upstream side of the AT&SF, 4th Street, and Sth Street
bridges, respectively. These figures represent what would happen at 135,000
cfs, which is the SOD-year frequency.

3-19. As discussed in paragraph 3-13 of this section, the "worst case"
consisted of levee breaks upstream of AT&SF and 8th Street bridges. The only
way to assure initial overtopping at the downstream end would be to provide
SPF protection upstream of the AT&SF bridge, which cannot be justified
economically. An additional allowance, totaling 4 feet of freeboard, will be
provided upstream of the AT&SF, 4th Street and Sth Street bridges, to account
for possible trash accumulations. Depths and limits of freeboard provided are
shown On Plates 4 through 6.

3-20. An item of omission in the Phase I report was that the levees were" 2 to
3 feet above the top of the road elevation at the point where they must tie in
to the 4th and Sth Street bridge abutments. HEC-2 backwater runs for the
design flow (S5,000 cfs) show the water surface elevation at low steel with
levees in place. A parapet wall will be used on the soil cement levee to
provide the desired freeboard in this reach. Since the parapet walls will be
providing freeboard only at both the 4th and 8th Street bridges, sandbagging
will be used across the bridges to attain the desired freeboard.

3-21. SEDIMENTATION - Channel Stabilitv Analvsis. The close examination of
aerial photographs for the years 1955, 1962, 1965, 1970, and 1976 indicate the
Fountain Creek low-flow channel through 'Pueb10 has experienced lateral

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