FS0018X Feasibility study

• Contract/PO #: FS0018X
• Contractor Name: Sterling, City of
• Contract Type: Loan
• Water District: 0
• County: Logan
• Loan Projects - Doc Type: Feasibility Study

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The Pawnee Creek/South Platte River confluence is located approximately 4 miles southwest of the
City of Sterling along U.S. Highway 6 (HWY 6) and the Union Pacific Railroad (UPRR). During
large storm events, stormwater overtops the banks of Pawnee Creek and flows into the City. These
overflows are estimated to be 5,000 cfs during the lOa-year storm. This study focuses primarily on the
reach along Pawnee Creek from its confluence with the South Platte River upstream to County Road
29 (CR. 29), a distance of about 7.5 miles. The Vicinity Map (Figure 2) presents the lower portion of
the Pawnee Creek Basin with respect to the City of Sterling. The Pawnee Creek Basin Map (Figure 3)
shows the overall Pawnee Creek Drainage Basin, along with a tabulation of pertinent basin
characteristics.

Previous Reports

Several studies have been completed to investigate the existing flooding conditions in the City of
Sterling and surrounding Logan County. Some of these studies address alternatives for mitigation to
the flooding problems. The City of Sterling is subject to flooding from four major sources which
include the South Platte River, Pawnee Creek, Sand Creek, and the Pioneer Drainage Ditch. One
recent study, "City of Sterling Drainage and Flood Control Implementation Plan" dated June 1997, by
ICON Engineering, Inc. concluded that addressing the flooding problems associated with the Pawnee
Creek should be given the City's highest priority, and would result in the most feasible and economical
plan of improvements for the area. As a result of flooding events that occurred in 1997 and discussed
in detail within this report, the City and County have determined that resolution of the Pawnee Creek
drainage problems must be appropriately implemented. The following reports were reviewed as a part
of this study:

Reference Reports:

1. Flood Hazard Mitigation Reconnaissance Study Pawnee Creek Basin, by ICON Engineering, Inc.
dated August 2000.

2. City of Sterling Drainage And Flood Control Implementation Plan, by ICON Engineering, Inc.
dated June 1997.

3. Pawnee Creek - Logan County, Colorado: Flood of July 1997, (Draft) by Colorado Water
Conservation Board, dated October 1997.

4. Flood Plain Information and Drainage Plan for Sand Creek and the Pawnee Creek Overflow at
Sterling, Colorado by Charles F. Leaf and Resource Consultants, Inc., dated May 1983.

5. Sand Creek Watershed, Sterling, Colorado by the U.S.D.A. Soil Conservation Service, dated
August 1984.

6. Summary Report, Flood Plain Information for Sand Creek and the Pawnee Creek Overflow at
Sterling, Colorado by Charles F. Leaf and Resource Consultants, Inc., dated January 1987.

7. Proposed Near-Term Improvements and Operation of Pioneer Drainage Ditch, Sterling, Colorado
by Charles F. Leaf and Resource Consultants, Inc., dated July 1988.

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