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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Selection of Phase B Plan

Once the above alternatives had been properly screened to determine the most
feasible flood control solutions, specific alternative plans were identified
within each study reach for evaluating the benefits and costs of implementing
the various plans.

Benefit/Cost Analysis

The Phase A Report presents detailed information regarding the economic
feasibility of various flood control alternatives and identifies secondary and
intangible benefits which are not quantifiable in terms of dollars. These
decision-making factors were considered carefully by the study team in presen-
ti ng recommended a lternat i ve plans in the Phase A Report. The recommended
plans were reviewed by the Urban Drainage and Flood Control District, the City
of Golden, and Jefferson County. A formal presentat i on of the recommended
plan was made to the Golden City Council to aid with final decision-making.
After a period of deliberation, the decision was made by the entities involved
to accept the consultant's recommendation and select the plan shown on Figure
V-2 for further study in Phase B. Specific direction was given to the
consultant (Muller Engineering Company, Inc.) by the Urban Drainage and Flood
Control District to proceed with the Phase B study. The "Selected Phase B
Plan" was outlined by the Urban Drainage and Flood Control District in a
written statement dated April, 1983, and is presented in Appendix A of this
report.

A key part of the Phase A study was evaluating the relative economic merits of
the various alternative plans selected during the initial screening process.
The benefit/cost analysis compares the tangible benefits expected from an
alternative flood control plan with the estimated cost of implementing the
plan. Tangible benefits are estimated in terms of dollars saved in annual
flood losses as compared with the "do nothing" alternative or base line
condition.

The benefit/cost analysis for Tucker Gulch showed unfavorable economic compar-
isons for the alternative plans studied. For the lower reach of Tucker Gulch
from State Highway #58 to the Clear Creek confluence, a benefit/cost (B/C)
ratio of 0.37 was estimated. For subsequent reaches upstream, even lower B/C
ratios were estimated as a result of the existing floodplain being undevel-
oped. Improvement of the State Highway #93 crossing of Cressmans Gulch was
estimated to be economically favorable with a B/C ratio of 1.33.

The benefit/cost analysis for Kenneys Run showed favorable economic compari-
sons for certain alternatives. A special analysis was conducted for alterna-
tives involving detention, since a detention alternative being studied within
a given study reach would result in benefits to downstream study reaches. The
B/C ana lys is suggested that the best economi c pl an woul d be one i nvo 1 vi ng
stormwater detent i on with selected downstream improvements. A B/C rat i 0 of
1.01 was estimated for the recommended alternatives.

V-2