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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quality, sacrificing aesthetic values and the effect on social,
political, and personal well being.

The benefit of undertaking flood control related improvements
along Van Bibber Creek, would be the reduction in the damage
potential due to future flooding. Undertaking certain improve-
ments which would reduce or eliminate the damage potential for
certain areas along the Creek would provide the benefit of
reducing the damage potential associated with that portion of
the Creek. By designing improvements to relieve the potential
flood damage for certain frequencies of flooding, the average
annual benefit to the community and property owners can be
determined by taking the difference between the average annual
damage potential before and after improvements. The benefit-
cost ratio is then determined by comparing the present worth
of the benefit for reduced annual flood damage potential, to
the cost of the project. The optimum project would tend to
maximize the benefit-cost ratio.

For the purposes of assessing damage to personal property,
depth-damage curves were utilized which relate the percent
of damage to a house by the depth of water inundating the house.
The curves used in this study were developed by the Federal
Insurance Administration. For the purposes of the Van Bibber
Creek study, a typical house type was considered to be a small
ranch with approximately 1,000 square feet of living space and
no basement. The house was considered to have a market value
of $27,000 and a lot value of $3,000. The contents of the house
were set at $8,000. For the purposes of assessing indirect
damages, the study followed the recommendations of the Soil
Conservation Service in their publication, "Economics Guide
for Watershed Protection and Flood Protection (Ref. 2). This
publication recommends that indirect damages be assessed as a
percentage of direct damages, as follows:

Residential area: 10-15%
Commercial & Industrial: 15-20%
utility: 15-20%

A more detailed summary of the damage-benefit potential analysis
is provided in the Phase A Report. Also included in that report
is a tabulation of the average annual damage associated with
various reaches along Van Bibber Creek, as well as the present
worth of the potential damage. Charts are also provided which
show the accumulated flood damage and accumulated benefits of
improvements within the creek. The overall benefit-cost ratio
of the improvements recommended in the Phase A report was 1.5.

The present worth of damage along Van Bibber Creek was estimated
to be approximately $18 million. Of this total, approximately
$12 million represents the present worth of flood damage within
the City of Arvada and $6 million within unincorporated Jefferson
County. The present worth of flood damage represents today's
value of the flood damage which will occur along Van Bibber Creek,
with present day channel conditions through the upcoming 100-year
period. The present worth is equivalent to the average annual
flood damage potential for Van Bibber Creek, approximately $1.5
million per year, based on a 50-year investment at an 8%
interest rate.

Legal Evaluation

A requirement of the Phase A planning was the completion of a
special legal evaluation of the proposed flood control alterna-
tives. The intent of the legal review was to outline possible
liabilities which may be associated with each alternative.

To accomplish this evaluation, the firm of Moses, Wittemyer
and Harrison, p. C. was retained and consulted. The attorney
became familiar with the problems associated with Van Bibber