FLOOD03503

• County: Jefferson
• Community: Golden
• Stream Name: Tucker Gulch, Kenneys Run
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 9/1/1983
• Prepared For: Golden, Jefferson County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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SEcn ON V I

aesthetics in mind, recognizing that sufficient right-of-way appears
to be available.

DESIGN CONSIDERATIONS, IMPLEMENTATION AND PROJECT COSTS

A grass-l i ned channel was also planned for emergency spill way flows
outletting from the Welch Ditch Detention Basin. The above criteria
also applies to the design of this channel.

The master plan presented in this report was developed utilizing design
criteria specified by the Urban Drainage and Flood Control District. This
section describes the criteria used in the Phase B preliminary design with the
intention that the same criteria be applied in final design. This section
also includes recommendations for operating and maintaining the improved
drainageways, planning open space uses, reducing adverse impacts on water
quality, regulating future floodplain development, and implementing the Phase
B plan. Cost estimates for the Phase B plan are summarized at the end of this
section.

2. Riprapped and Structural Walled Channels - Riprapped channels were
planned to accomodate higher-velocity flows where right-of-way
availability is limited. It is recommended that hard solutions, such
as ri prapped channels, be used with di scret i on and then on ly to
accomodate existing development for minimum reaches. The following
criteria applies to riprapped channels:

. Riprap size, bedding, design velocities, and "n" values should be
based on latest UDFCD criteria (Ref. 10).

Channel Improvements

The design criteria for the recommended channel improvements were based on the
UDFCD Urban Storm Drainage Criteria Manual (Ref. 10). Grass-lined and
rock-lined channels were utilized in this master plan. The use of
concrete-lined channels was eliminated considering the steep stream gradients
and complications associated with the design of supercritical channels. The
following categories of channel improvements were util ized in this master
pl an.

. Where steep slopes and limited R.O.W. results in higher flow
velocities than the normal criteria permits, the channel should
be designed such that the Froude No. for the design flood does
not exceed 0.8.

. A maximum side-slope of 2.5:1 is recommended.

1. Grass-lined Channels - A grass-lined channel was planned for the East
Fork Kenneys Run from the outlet of the Interurban Railroad Detention
Basin to the inlet of the East Fork storm sewer. The channel was
sized to carry flows up to a 10-year event with minimum freeboard of
1.0 foot. Side slopes of 4:1 or flatter should be used unless
right-of-way is limited, in which case, grass-lined side slopes up to
3: 1 may be used. Maximum design velocities should not exceed 7.0
feet per second for the 100-year flood calculated to flow at normal
depth. The grass-lined channel was selected for this reach with

. In designing vertical concrete walls, consideration should be
given to freeze/thaw action, groundwater, the effects of
expensive soils and protective fencing.

. Trickle channels are sized to carry approximately 1% of the
design flow.

Riprapped channels are planned for the West Fork Kenneys Run through
the Golden High School property to a point approximately 300 feet
downstream of 23rd Street and for Cressmans Gulch in conjunction with
the Foss development plans. A grouted riprap channel is proposed for
the trickle channel throught the Welch Ditch Detention Basin to
minimize maintenance problems. A structural walled channel with a

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