FLOOD05064

• Designation Number: 205
• County: Larimer
• Community: Fort Collins
• Basin: South Platte
• Title: Master Drainageway Planning - Cooper Slough, Boxelder Creek, Fort Collins, Larimer County, Colorado
• Date: 8/1/1981
• Designation Date: 1/1/1983
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Table 25. Alternative 3, Design Data for Sizing Detention Pond.

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3. Colorado an<'l
southern Railroad

108

350

5.6

8

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VII. IMPROVEMENT COSTS

'rhe development of construction costs for the alternative improvements

was based on unit costs obtained from 19BO construction cost estimates. A

summary of the unit costs used in the cost estimates are shown in Table 27.

All unit costs include labor and overhead for the construction item.

Quantities were estimated for each alternative on a reach by reach basis.

Included in the cost estimates are costs for land acquisition and legal admi-

nistrative and engineering fees. Generally land acquisition costs were

assumed to be $10,000 per acre. Along Reach 1 of Cooper Slough the land is

zoned commercial and/or industrial and land acquisition costs of $20,000 per

acre were used. Annual operation and maintenance costs were based on $60 per

acre for detention ponds and $0.50 per linear foot for channels.

The detailed cost estimates for each alternative on a reach by reach

basis are presented in the next tables. Tables 28 thro~gh 30 present the

estimated costs for common improvements necessary in both Alternatives 2 and

3. Tables 31 through 36 present the estimated costs for channel and bridge

improvements required in Alternative 2 for the 10-, 50- and 100-year design

flows. Tables 37 through 39 show the estimated costs for Alternative 3. A

summary of the total cost estimates for Alternatives 2 and 3 are presented in

Tables 40 through 43. The total annual cost of Alternative 2 for the 100-year

design frequency (Table 42) is $429,500 as compared to $368,300 for Alterna-

tive 3 (Table 43). These estimates do not include the cost of channel

improvements and/or detention storage upstream of Vine Drive on Cooper Slough

since damage estimates for this area were not defined. The estimates do not

include the cost of the channel improvements along reaches 2 and 3 of Boxelder

Creek. Damage reductions are not signficiant along these reaches and will not

justify these improvements. The annual costs were based on a 50-year project

life with a 7 3/B percent discount rate.

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Location

Storage
volume
(ac-ft)

Outlet
Capacity
(cfs)

Average
Depth
(ft)

Maximum
Embankment
Height
(ft)

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cooper Slough

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1. Highway 14

112

300

7.5

10

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2. Highway 14 near
Lake Canal

78

50

6.0

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4. Vine Drive

75

300

x

x

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5. Upstream of vine Drive

130

228

x

x

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x = Ponds not located

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Table 26. Alternative 3, Design Data for Culverts Along
Cooper Slough.

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Location

Design Flow
(cfs)

Dimension
(in ft)

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Vine Drive

300

4 x 10

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Colorado and Southern
Railroad

350

2-4 x 7

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Sherry Road

300

4 x 12

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69

6B

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