FLOOD03463

• Designation Number: 72
• County: Adams
• County: Arapahoe
• County: Douglas
• Community: Denver Metro Region
• Stream Name: Van Bibber Creek
• Basin: South Platte
• Title: Major Drainageway Planning - Van Bibber Creek
• Date: 3/1/1977
• Designation Date: 7/1/1977
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Costs are associated with this alternative in the form of mainten-
ance costs. As the alternate essentl'ally , .
malntalns status quo,
maintenance operations must be undertaken to assure the present
capacity of the drainageway. The following cost and benefit
summary relates the ecomomic aspects envisioned for this
alternate approach, on a present worth basis:

in the flood plain. Regulatory measures would be implemented
to restrict undesirable flood plain land uses. Potential
sources of debris would be removed from the flood plain.
Generally, the potential flood damage on the creek would be
eliminated through corrective measures and regulatory controls as
well as the physical removal of selected damage sources.

P.W. Benefits

Arvada
Jefferson County

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$ 23,000
680,000

(-) $ 23,000
(-) 680,000

Street and irrigation crossings would be improved to a feasible
capacity. Since potential benefits to be derived on the
creek were of the same magnitude for both the la-year and lOa-year
event, improvements were considered for both design frequencies
for this alternate.

P.W. Costs* Net Benefit B/C

*Phase A Estimated Costs

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Alternate 2 - This alternate proposed a combination of structural
improvements through Arvada and minor flood improvements through
Jefferson County. The intent of this alternate was to resolve
existing problems through corrective improvements and to
eliminate future problems through strong regulatory measures.

All irrigation ditches should be improved to convey the lOa-year
event across the irrigation ditch alignment. Most of the
ditches have separated crossings with limited capacity. The
crossings should be improved to pass the 2-year to la-year
event through the structure before overtopping the canal. In
all cases, the improvement would be capable of passing the
excess flows through the lOa-year frequency, over the top of
the ditch without overtopping at some other point. In essence,
a controlled spill or wasteway would be provided on the ditch
along the drainageway alignment. Low flow structures would
consist of a simple culvert or a siphon. Overflow structures
would be concrete or rock-lined spillways.

The structural improvements proposed for Arvada include an
enlarged major conduit from Garrison Street near Ralston Road
to Kipling Street. From the downstream end of the conduit to
Ralston Creek, the open channel would be maintained to a capacity
equivalent to the conduit. Upstream of Kipling, an open, hard
and soft lined channel would be installed and realigned to the
south side of 58th Street. The channel would be incorporated into
the 58th Street widening program and be made compatible with
both the street system and park area through which it passes.
Relocating the channel within the flood plain to the porposed
alignment would eliminate five crossing structures.

The economic comparison of improvements for each design
frequency showed that lOa-year improvements are justified in
Arvada and la-year design improvements through Jefferson County.
With a la-year design, provisions would be made for passing
the lOa-year flow. The lOa-year flood plain resulting from
flows in exeess of the design flow would be regulated by
ordinance. Nonstructural measures would be undertaken as

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Through Jefferson County, the proposed minor flood plain
improvements included a variety of flood control measures.
Channel improvements would include check dams, realignment of
channel and improved natural cross-sections to stabilize
the channel and minimize local scour and erosion. Improvements
would also include flood proofing measures on structures already