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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obtained from the City of Milwaukee and the City of Los
Angeles, could range from $3,500 per mile per year to $16,000
per mile per year, dependent on maintenance cost accounting
procedures. The higher figure includes cost for office
administration, equipment rental depreciation, materials,
as well as normal salary and direct operating costs incurred
in mowing, cleaning and repairing drainageway facilities.
Direct salary cost for maintenance work could be on the order
of $4,000 to $6,000 per year per mile, assuming overhead
and equipment and materials costs included in a factor of
2 to 3 times base salary cost. Most of the areas in Milwaukee
have well kept blue grass linings through park areas which will
require maintenance on a much more frequent level. The $3,500
per year per mile figure obtained from the City of Los Angeles
is based on maintenance requirements for concrete lined
channels.

reduction of peak flows and in regard to settling out of
sediment and debris, the latter helping to improve the
quality of water downstream. These embankments should be
suitably planned and designed to provide for the passage of
lower flows through the reservoir. This requires careful
sizing of the outlet works. Normally, the planning
should be such that the major storm will cause water to rise
within the pond areas up to the design maximum water level.
With usual earth embankments, in the event of a storm greater
than the major design storm runoff, an emergency spillway
must be provided to preclude the possibility of the embankment
being overtopped, which might lead to an embankment failure.

Irrigation Ditch Crossings

Final design must be preceeded by a detailed soils investigation.
Also, special hydrologic studies should be completed to ascertain
the extent of probable maximum or standard project flood conditions
to which the reservoir and embankment may be subjected. Final
plans for the reservoir must comply with the State Engineer
criteria.

When possible in this plan, all major irrigation ditch crossings
have been designed to pass the lOa-year flood without comingling
irrigation and storm water at the drainagewaY/irrigation ditch
crossing. Special consideration and compromise is given those
irrigation ditches which possess a water right for tributarv
storm runoff. At such locations, special structures, which
permit controlled spillage from the irrigation ditch, should
be used. This criteria has been reviwed with the UD&FCD, the
entities and the various irrigation companies and represent means
of minimizing potential flood hazards which might result from
the breaching of irrigation canals.

- DRAINAGEWAY IMPROVEMENTS -

Flood Storage Reservoirs

The drainageway improvements which have been studied and
considered for Van Bibber Creek are outlined on the attached
drawings. The intent of the master plan drawings is to provide
an overall plan of drainageway improvements. This systemized
approach is aimed at assuring that all aspects of the proposed
drainageway improvements will be complementary and not conflict
with improvements in other reaches. The plan is of minimum
detail to outline intent and to provide a basis for future
planning, financing and implementation.

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The construction of embankments in the chanu81, generally
where topography is favorable to the storage of storm runoff
water, will provide significant benefits in regard to the

The detail of the preliminary plans outlined on the drawings