FLOOD04800

• County: El Paso
• Community: Colorado Springs
• Stream Name: Cottonwood Creek
• Basin: Arkansas
• Title: Engineering Study of Cottonwood Creek Drainage Basin
• Date: 8/7/1979
• Prepared For: Colorado Springs
• Prepared By: Lincoln Devore
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Storm Sewer and Ditches - Individual Improvements

Attention is directed to Appendices

C, D, E, and F which list individual improvement recommendations

for the studied portion of the basin. These also list major exist- .

ing drainage structures within this portion of the basin. Also

included is a set of maps of the basin showing existing and recom-

mended drainage structures within the basin. The discussion in

this section will be limited to major construction and will be

general in nature.

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After study and sizing of the main
channels, each individual basin in the study area was studied

using the predicted 5-year and 100-year runoff of each. Runoff at

various points in each basin was compared to actual or probable

street capacity and distribution. Street capacity used for the

computation was in accordance with the City chart of allowable

street runoff. In some cases, runoff was spread over a sufficient

number of streets that no drainage system was required, other than

dropouts into the main channel. In other cases, flow is concentra-

ted and a drainage system was found to be required.

The City drainage criterion for drain-

age construction can be paraphrased as: All drainage structures

in areas in which the 100-year frequency flow is projected as

greater than 500 cfs will be designed for the 100-year frequency

flow. Where the 100-year frequency projection is for less than

500 cfs, all structures will be designed for the 5-year frequency

flow. According to this criterion, practically all of the main

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