FLOOD03016

• County: El Paso
• Community: Colorado Springs
• Stream Name: Arkansas River and Tributaries
• Basin: Arkansas
• Title: Areawide Urban Runoff Control Manual
• Date: 9/28/1979
• Prepared For: Pikes Peak Area Council of Governments
• Prepared By: Gilbert Meyer & Sams
• Floodplain - Doc Type: Miscellaneous

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3. Maintenance provisions

Side slopes on unlined channels shall be a maximum
of 3:1 to allow for mowing. Side slopes on lined
channels will be governed by structural considerations,
but provisions for vehicular access shall be made.
All major channels (>500 cfs) shall have a 12 foot
access road adjacent to the channel.

4. Low Flow Trickle Channels

Unlined channels shall be designed with provisions
to convey trickle flows at a minimum of two.f~~Lper- -~,
second. The capacity of the trickle channel (or
underdrain pipe) should be approximately one percent
of the design flood flow.

5. Eros ion

All channels will be designed with appropriate erosion
control measures where erosive velocities are liable
to occur. Reference is made to Section V of this manual
for suggested protective measures.

6. Curvature

The centerline radius of curvature of channels shall
be greater than three times the design flow top width
or 100 feet, whichever is greater. Curves shall be
placed only in sections of subcritical flow. Increased
freeboard or bottom superelevation shall be provided
to account for centrifugal action in the curve. This
increase in freeboard may be approximated by the equation:

h =

V2b
gr

where:

h = superelevation on curve, feet
V = velocity of flow, feet per second
b = top width of channel, feet
g = acceleration of gravity, feet ,:>er second2
r = radius of curvature, feet

B. Street Flow

Analysis of street flows can be made with open channel flow
techniques. A refinement of the Manning equation, developed by

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