FLOOD03286

• County: Adams
• Community: Wheat Ridge, Arvada
• Stream Name: Lower Clear Creek
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 10/1/1981
• Prepared For: Adams County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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C-l

INTRODUCTION

APPENDIX C

It is important that the criteria used for design be WE'll-conceived, so as to
maximize the benefits to be obtained from each alternative and to insure that
the major drainage system will operate as intended. The design criteria
utilized for this planning study are based on those contained in the Urban
Storm Drainage Criteria Manual, Volume Nos. 1 and 2 (Reference 40), and other
acceptable criteria for the Denver metropolitan arp.a. It should be recogniz-
ed that the following criteria are general and are intended for a wide
variety of streiJ11 regimes. Lower Cl ear Creek may have many reaches which
have a natural cobble bed, therefore, consideration must be given to each
reach of the creek to determine which design criteria are applicable.

RECOMMENDED STRUCTURAL CRITERIA FOR MAJOR DRAINAGEWAYS

STRUCTURAL CRITERIA

1. Grass-Lined Artificial Channels. Design will generally be based on chan-
nel s having natural waterway h}{lraul ic and appearance characteristics.
They should be aesthetically designed to the local environment and useful
for local recreation continuous along the channel. Criteria include:

o A maximum average design velocity of 7.0 feet per second (fps) for the
100-year storm in accordance with the Denver Regional Council of
Governments criteria for different grass and soil types.

o Maximum depth on overbank of up to 5 feet.

o 4:1 channel side slopes; however, where developllent exists and right-
of-way is a problem the slopes may be 3:1.

o Centerline curvature of twice the top width.

o Freeboard equal to velocity head (expressed in feet) plus 0.5 feet,
but no less than 1.0 foot and not to exceed 3.0 feet.