FLOOD06450

• Designation Number: 92
• County: Jefferson
• Community: Arvada
• Stream Name: Ralston, Leyden Creeks
• Basin: South Platte
• Title: Major Drainageway Planning - Ralston/Leyden Creek, Arvada, Jefferson County, CO
• Date: 8/1/1977
• Designation Date: 1/1/1978
• Floodplain - Doc Type: Floodplain Report/Masterplan

i'

I

I

I

SECTION I X

TABLE IX-l

MASTER PLAN COST ESTIMATE

UNIT PRICES
(Apri 1 1976)

I

During Phase A, a benefit/cost analysis was completed, which while broad
in form, served to identify the alternate and the Frequency to be used
in conjunction with the designated alternate.

CONCRETE - Structural
Vertical walls
European type walls
Slab

Item

I
I

Major drainage channels are often costly in an urban area because of right-
of-way~ bridges, and culverts, special structures, and in some places, re-
taining walls where a narrow channel must be designed. Many of these costs
can be attributable to other urban systems such as streets and traffic, rec-
reation and open space, and land development. The cost estimate brings all
costs together in the total figure; however, the financing strategy should
differentiate between the incremental costs when developing funding sources.

BRIDGES - New
Add to existing
Replace existing (with same)
Small foot bridges

I

I

Total cost of construction and land acquisition for the master plan was ob-
tained and reduced to an annual cost. The I ife of most structures associ-
ated with drainage work is estimated to be 50 years; therefore, initial
costs were amortized over a 50-year period using a 6-3/8 percent interest
rate. Construction costs were estimated using the unit price listed in
Table IX-l, which updates the prices used in Phase A as shown in Section VI.

1,500 cfs capacity/barrel

SUPER SPAN CULVERTS
1,000 cfs capacity/barrel

I

I

EARTH WORK
Excavation - Urban
- Ru ra I
- Ponds
- Closed Conduit
- Structural
- Mole tunnel
Placement - Structural
- Dam embankment
(Excavation & fill)
Riprap - Placed
- Gabion
- Grouted
Dumped

I

The costs of land were determined by entity input during Phase A as to the
reasonable market value of developed and undeveloped lands. The cost of
land listed in Table IX-1 is given for land that can be acquired without
structures, such as portions of backyards. This figure considers the Fact
that, although portions of property will be lost by the owner, benefits
in the form of protection From future damages will more than offset any
individually perceived losses.

I

The construction costs have been broken down for each entity into: channel
construction costs, bridge construction costs, and right-of-way cost. The
costs include estimated contract values and an allowance of 30 percent ad-
ditional, which can be allocated generally:

I

I

Design engineering
Surveys and staking
Construction inspection
Administrative overhead
Fiscal and legal expense
Contingencies, Miscellaneous

9 %
3 %
3 %
1.5%
3.5%
10 %

GRASSING - Natural - seeded
- Blue Grass - seeded

I

CLEANUP

I

30 %

LAND (WITH NO STRUCTURES)

I

Total master plan costs, reach by reach, for traffic modifications, channel
improvements, utility relocation and property acquisition are presented in
Tables IX-2 and IX-3.

I

I

IX-l

Unit

Cost ($)

c.y.
c.y.
c.y.
c.y.

235

115
90

s. f.
s. f.
s. f.
s. f.

25
35
15
5

1.f.
s. f.
1.f.
s. f.

275
15
375
17

c.y.
c.y.
c.y.
c.y.
c.y.
c.y.
c.y.

1. 75
1.25
1.00
2.00
3.00
6.00
3.00

c.y.
c.y.
c.y.
c.y.
c.y.

0.90
25
75
50
20

acre
acre

1,500
1,500

acre

1,000

acre

6,000