FLOOD07758

• County: Denver
• County: Jefferson
• Community: Lakewood, Denver, Jefferson County
• Stream Name: Lakewood Gulch
• Basin: South Platte
• Title: Major Drainageway Planning
• Date: 12/1/1979
• Prepared For: Denver / Lakewood / Jefferson County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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and the addendum to the Phase A report (Reference 6) presented
a number of different alternatives which could be considered for
reducing flood damages along the channel. The Cities of Lake-
wood and Denver, and Jefferson County, in conjunction with the
Urban Drainage and Flood Control District, established guide-
lines for the selected alternative. The selected alternative
was then evaluated in detail and a preliminary design prepared
in this report.

2
1st Phase 2nd Phase Total
Denver $ 2,500,207 $ $ 2,500,207
Lakewood 2,663,620 1,745,464 4,409,084
Jefferson County 37,935 37,035
TOTAL PROJECT COSTS $ 5,201,762 $ 1,745,464 $ 6,947,226

Benefit Cost Analysis

In the Phase A report, the estimated costs of construction and

right-of-way acquisition were determined for each of the various

alternatives. The benefits to be derived by construction of

each alternative were then determined by subtracting the antici-

pated flood damages which would occur after construction from

those which would have occurred without construction. In this

Phase B report, the construction and right-of-way costs and the

anticipated benefits have been updated to December 1979 and

estimated in greater detail. The proposed construction of the

master plan for Lakewood Gulch is estimated to cost approximately

$5,201,762 (December 1979) during the first construction phase

and $1,745,464 (December 1979) during the second construction

phase. The following table illustrates the distribution of

these costs:

The recommended Master Plan for the entire basin has a benefit-

cost ratio of 0.47. Benefit-cost analyses were made for ten

different reaches, yielding benefit-cost ratios ranging from

0.09 to 8.46. These benefit-cost ratios are based exclusively

upon flood damage reduction as benefit and illustrate that

facilities in certain reaches are more cost-effective than

those in other reaches. However, much of the estimated cost

is for maintenance access needed by the Urban Drainage and

Flood Control District, Denver and Lakewood to maintain the

drainageway in a satisfactory manner. Benefits of providing

maintenance access were not quantified.

The Master Plan

The Master Plan for Lakewood Gulch consists essentially of pro-

posed facilities to convey the laO-year flood in accordance

with the recommendations of the Urban Storm Drainage Criteria

Manual and additional criteria as directed by the Cities of

Lakewood and Denver and Jefferson County in cooperation with

the Urban Drainage and Flood Control District. All of the

proposed improvements are illustrated on the Major Drainageway