FLOOD10417

• County: Mineral
• Community: Mineral County
• Stream Name: Willow Creek
• Title: Willow Creek Channel Improvement, Mineral County, Colorado - Channel Replacement Feasibility Report
• Date: 8/13/2003
• Prepared For: Willow Creek Reclaimation Committee
• Prepared By: Chou Cha, P.E., Civil Engineer
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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APPURTENANCE STRUCTURES

Appurtenance structures recommend to be installed would be traffic guardrails, safety
cables in channel, new pedestrian bridges, and a flow dissipating structure at the
downstream end. The safety cables and pedestrian bridges are only applicable to
Alternatives 1 and 2. The traffic guardrails and the flow dissipating structure should be
installed for any of the chosen alternatives. The cost for 775 feet of vehicle guardrail
installation is $13,600. The cost for the safety cables to be installed for Alternative 1 and
Alternative 2 will be minimal. The field cost for eight new pedestrian bridges for
Alternative I is estimated at $203,000 and for Alternative 2 is estimated at $145,000
including bridge abutments. The field cost for constructing the flow dissipating structure
is estimated at $55,000.

DESIGN AND CONSTRUCTION ELEMENTS

Field design data is needed by NRCS NPET to design the channel replacement. Design
data necessary to complete construction drawings would include land surveys, structure
surveys, utility surveys, and a geotechnical investigation. Design data cost to the WCRC
would be for a surveying service contract, utility locating contract, and an operator and a
piece of heavy equipment for the geotechnical investigation. The cost for the surveying
contract is $12,000 and for the utility location contract is $2,500. Estimated cost for
excavation equipment and operator is $2,000.

NRCS NPET would develop the construction drawings, specifications, and design
summary. Construction permits would need to be obtained from local, county, state" and
Federal government agencies. The Willow Creek Reclamation Committee would
administer the construction contract and provide the necessary inspections.

NRCS NPET's time required for the final design of this project is shown in Table 3. The
estimated time to collect design data is 19 days. The estimated time required to do design
calculation and drawings is estimated at 151 days. The time required for writing the
specification, estimating the cost, and writing the design summary is estimated at 45
days. The design and document estimated above include review time. The time
requirement for construction oversight and submittal reviews is estimated at 20 days.
The times estimated do not include contract phasing. Contact phasing means that the
construction ofthe project will be broken down into multiple parts and each part would
be a separated construction contract. Therefore if the construction of the 5,070 linear feet
channel is separated into more than one contract these estimates will need to be revised.

Design and construction schedules could not be determined at this feasibility level. The
construction schedule should consider the varying flow of Willow Creek and the extreme
temperatures during the winter months. The recommended construction window would
be from July to October.

NRCS Northern Plains Engineering Team V