FLOOD10480

• County: Fremont
• Community: Canon City
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: Canon City Flood Control and Drainage Analysis
• Date: 9/1/1996
• Prepared For: Canon City
• Prepared By: WRC Engineering, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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INTRODUCTION

The purpose of this Report is to review existing hydrologic and hydraulic studies of a 6,265 foot reach of the
Arkansas River at the western boundary of the Cafton City corporate city limits and to evaluate potential
alternatives for flood containment. Cafton City (City) contracted with WRC Engineering, Inc. (WRC) on May
8, 1996 to perform the following tasks:

1) Review existing hydrologic and hydraulic investigations/studies related to the Reach

2) Format and construct HEC-2 models for the Reach including sections to model the diversion weir and
the whitewater bypass

3)

Compute water surface elevations for the 10-, 50- , 100-, and 500-year flood events

4) Prepare a set of conceptual alternative improvement plans (and corresponding costs) for the
containment of the lOa-year flood event and make recommendations for selection of a specific plan.

5) Determine the residual lOa-year floodplain based on the selected alternative.

The City was particularly concerned with flooding of approximately 5 acres of private farmland located on
the south bank of the Arkansas River upstream of the City's water supply intake diversion weir and other
property which is located in the lOa-year floodplain. Preliminary estimates of improvements needed to protect
these private properties from the lOa-year event were deemed expensive and potentially detrimental to
property owners on both banks. During a meeting with the City on August 12, 1996, WRC was asked to
modify the scope of services for the project. The City asked WRC to evaluate alternatives that would provide
this property with the same level of protection that the existing levee provided before construction of the
City's diversion weir and whitewater by-pass.

II.

STUDY AREA

The Arkansas River Reach (Reach) analyzed in this report begins at the western corporate limits of Cafton
City and extends 6,265 feet downstream (east) to First St. Exhibit A shows the vicinity map from the Flood
Insurance Study (PIS) with the upstream and downstream limits of the Reach labeled as "WRC Study Limits" .

WRC relied on site data and maps from several sources (See References Section) which was provided by the
City of Cafton City. Data used for evaluating existing conditions included City provided aerial photography
(prepared by Kucera West, taken March 21, 1994) on a 1" = 1 00' scale. Federal Emergency Management
Agency (FEMA) Floodway 1" =200' topographic maps (November 3, 1982), Water Treatment Improvement