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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EXECUTIVE SUMMARY

INTRODUCTION

The U.S. Department of Agriculture, Natural Resources Conservation Service (NRCS),
Northern Plains Engineering Team (NPET) conducted this feasibility report for the
Willow Creek Reclamation Committee (WCRC). The purpose ofthis feasibility report is
to present the replacement alternatives and their estimated costs. Appurtenance structures
are also presented with their cost estimates as a part of this replacement feasibility r'eport..

PROJECT LOCATION

Willow Creek Channel is located in the town of Creede, Colorado. Creede is located in
Mineral County on State Highway 149.

BACKGROUND

The Army Corps of Engineers designed the existing Willow Creek Channel through the
town of Cree de, Colorado and finished construction in 1950. The grouted hand placed
rock channel is a trapezoidal section with a bottom width of 8 feet and side slopes of 1 ~
to 1. The channel has several vehicular bridge crossings. The design discharge flow for
the existing channel is 1,800 cubic feet per second (cfs). The channel is plagued with
maintenance problems and will potentially fail during a flood event with discharges less
than that designed. The replacement design discharge to be used will also be 1,800 cfs as
agreed to with the Colorado Water Conservation Board.

REPLACEMENT

A complete replacement would include demolition and disposing of channel material, and
new construction. The replacement will utilize the existing horizontal alignment of the
channel. The removal of a railroad bridge is recommended. Complete replacement will
satisfy design discharge, address foundation problems, and utilize current construction
methods and materials. The replacement disadvantages are cost and construction access.
Replacement construction will be from the inlet transition to the downstream end of the
hand placed rock channel. The inlet embankment dike, cutoff sill, and all vehicle bridge
crossings will not be disturbed during construction.

DEMOLITION

Demolition of the existing channel will include breaking up and removal of channel rock
and mortar. Demolition materials could be used for other projects but may not be
suitable as aggregate in the new concrete without testing. The estimated field cost fi)r
demolition is $274,000.

NRCS Northern Plains Engineering Team III