FLOOD05819

• County: Logan
• Community: Sterling
• Basin: South Platte
• Title: City of Sterling Drainage and Flood Control Implementation Plan
• Date: 6/1/1997
• Prepared For: Sterling
• Prepared By: ICON Engineering, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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II. INTRODUCTION

Authorization

This study was authorized and funded jointly by the Colorado Water Conservation Board and the City
of Sterling, Colorado. The study was contracted through the City of Sterling in an agreement with the
Denver Office of Greenhome and O'Mara, Inc. dated January 23, 1996. ICON Engineering, Inc
purchased the Denver Office of Greenhorne and 0 'Mara in February of 1997 along with the contract
for this study. This report was subsequently completed by ICON Engineering, Inc

Objective/Scope

Beginning in 1983, several studies were completed which investigated the existing flooding potential
in the City of Sterling and addressed many alternatives for mitigation to the flooding problems within
the City. The purpose of this report is to review the existing work completed to date, and develop the
most feasible and economical plan of improvements for the City to undertake. The City has a limited
annual budget available for the design and construction of flood control and drainage projects.
Therefore, the objective of this report is to develop an implementation plan which prioritizes the
proposed improvements so that the City can use this study as a guide for budgeting future drainage and
flood control improvements.

The following is a summary of the scope of work completed for this study:

Review of Existing Reports: All of the existing reports were reviewed to determine if the proposed
improvements are applicable given today's guidelines and requirements. The project proposals and
recommendations from the existing studies were evaluated and updated as required.

Hydrology: The hydrology from the existing reports was reviewed and utilized in this report.

.. Hydraulics: Several HEC-2 models were prepared as a part of earlier studies to evaluate the existing
flooding conditions. The models were reviewed and updated for this study. In order to evaluate the
proposed improvements, the updated models were revised and residual floodplains were delineated.

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Development of a Selected Plan of Improvements: Based on a review and update of existing studies
and input from the project sponsors, a selected plan of improvements was established for each of the
major drainageways. A conceptual level design was completed for all of the proposed improvements
and a project cost was prepared,

Prioritization Plan: A prioritization plan was prepared for all of the improvements based on an
implementation matrix which was developed for all ofthe proposed projects.

Study Streams and Limits

The major drainageways studied in this report include Pawnee Creek, Sand Creek, and the Pioneer
Ditch. Pawnee Creek is a left bank tributary to the South Platte River. Its confluence is located
approximately 4 miles southwest of the City of Sterling along HWY 6 and the UPRR. During large

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