FLOOD02057

• County: Morgan
• Community: Weldona
• Title: Hazard Mitigation 404 Grant Application
• Date: 1/30/1998
• Prepared For: FEMA
• Prepared By: CWCB
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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I. INTRODUCTION

A, PURPOSE OF REPORT

The purpose of this report is to document the results of a flood hazard mitigation feasibility study which was
completed in order to assist Morgan County with the preparation of an application for the Hazard Mitigation
Grant Program (HMGP). An intense rainstorm occurred north and east of Weldona on the evening of July
29, 1997. The storm produced flood flows in Schaefer Draw above Weldona and in an equally large
unnamed watershed to the west of Schaefer Draw. Storm runoff from these watersheds combined with
spilled flows from the irrigation canals north of We Idona to inundate nearly the entire community. Residents
were evacuated from their homes due to flood hazards and potential health hazards. Flood depths were from
I to 3 feet.

Morgan County officially received a federal disaster declaration on August 1, 1997 based on severe
flooding conditions. The declaration made it possible for Morgan County to be eligible to receive federal
funding (disaster relief) which includes individual assistance, public assistance, and mitigation assistance.

This report will detail proposed alternative mitigation plans, evaluate the cost and intangible elements (e.g.
environmental concerns, level of protection, cost effectiveness) for each alternative plan, recommend a
specific alternative plan for further evaluation and provide a preliminary design of the selected alternative.

B, SUMMARY OF REPORT

This report presents the hydrologic analysis and development and analysis of alternative mitigation plans for
the Community of Weldona Flood Hazard Mitigation Project. This study is a jointly sponsored effort by
Morgan County and the Colorado Water Conservation Board. The report represents a synopsis of the
project history, a summary of the project study area, project area hydrology, evaluation of existing facilities
and identification of problem areas, discussions on the evaluation of alternative plans and recommendation
of an alternative mitigation plan.

Four alternative plans were developed to alleviate the flooding problem in Weldona. The alternatives
evaluated are as follows:

Alternative 1. No action.

Alternative 2. Diversion channelJring levee without upstream detention,

Alternative 3. Regional detention reservoir north of Weldona in Schaefer Draw.

Alternative 4. Floodproofing and/or elevation of flood prone structures.

Alternative 2 was selected as the most desirable alternative considering cost effectiveness, constructability
and the concerns of County officials and local citizens. The selected alternative presented herein meets the
flood control goals of the project and FEMA requirements for the HMGP application.

The major components of this alternative, which is planned for the lOO-year flood frequency, include:

. Construction of a channel and ring levee to divert the runoff from Schaefer Draw around Weldona.

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