FLOOD01117

• Designation Number: 219
• County: Arapahoe
• Community: Littleton
• Stream Name: Upper Slaughterhouse Gulch
• Title: Major Drainageway Planning - Upper Slaughterhouse Gulch
• Date: 3/1/1983
• Designation Date: 7/1/1983
• Floodplain - Doc Type: Floodplain Report/Masterplan

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The selected alternative plan is a combination of selected structural improve-

ments, major conduit, channelization, and detention. The selected alternative plan

for the various reaches is presented below:

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Reach-A - Storm sewer, (S-year protection with installation of Reach-D
improvements) .

The Present Worth (P.W.) is the present sum of the series of average annual

costs (AVG ANN) over the project life accounting for the time value of the money,

Based upon 1983 costs, 8.S7. interest rate, and a 50-year project life of a project,

the present worth of the potential flood damages is $8,687,000. The implementation

of the selected alternative will cost $3,911,SOO and will result in benefits of

$7,8S7,700. The benefit-cost ratio will be 2: I.

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Reach-B - Channelization, (S-year protection with installation of Reach-D
improvements) .

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Reach-C - Storm sewer, (S-year protection with installation of Reach-D
improvements).

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Reach-D - Selected structural and detention (Caley Detention Dam).

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Reach-E - Storm sewer, (S-year protection).

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A summary of the benefits and costs for the selected plan is presented in the

following table by political jurisdiction. The DAMAGES listed are the total damages

for the status quo drainageway condition. The costs associated with the recommended

alternative is listed under IMPROVEMENT COST, and the potential damages remaining

after implementation of the plan are listed under RESIDUAL DAMAGES. The benefits

derived from the selected plan are presented under BENEFITS. The NET BENEFITS

derived from the selected alternative plan is the difference between the BENEFITS

and the IMPROVEMENTS COST. The TOTAL ANNUAL COSTS are the sum of IMPROVEMENT COST

and RESIDUAL DAMAGES.

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BENEFIT/COST COMPARISON
SELECTED ALTERNATIVE PLAN
(1000 DOLLARS)

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DAMAGES
AVG
JURISDICTION ANN P.W.
Littleton 585.9 6.776.3

Arapahoe 165.2 1.910.1
County

TOTAL ANNUAL
niP. COST RES, OAK. BENEFITS NET BENEFITS COSTS
AVG AVG AVG AVG AVG
ANN P.W. ANN P.W. ANN P.W, ANN P,W, ANN P.W.
130.1 1.504.7 6~.1 7~2.9 ~20.8 6,023.4 390.7 4,~18.7 19~.2 2,2H.6
176,3 2,039.0 6,6 76.4 1~8.6 1,834.3 -49.~ -~72.~ 214.7 2,483.2

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TOTAL

7~I,1 8,687.0 338.2 3,911.~ 71.7 829.3 679.4 7,8~7.7 341.2 3,946.2 409.9 4.740.8

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