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 results of the analysis indicate that Alternative No. 5 is the most beneficial project to
pursue. This alternative ranked highest among the six alternatives evaluated because it
provides a relatively large benefit for the cost.

After extensive analysis, a multitude of presentations to the public, and several revisions
of the design elements, Alternative No.5 was selected as the preferred solution. Primary
reasons for selection of this alternative included:

. Partial protection of Town of Atwood
. Best use of existing Pawnee Creek Channel
. Best level of protection for Sterling
. Partial protection of farmlands bordering HWY 6

In general, it makes the most sense to construct drainage improvements from downstream
to upstream. The selected Pawnee Creek project is no exception because upstream
improvements will increase flows in the lower reaches. If improvements have not been
completed in the lower reaches to properly convey the increased discharges, then
flooding conditions can be made worse. Therefore, it is recommended that the Pawnee
Creek project be constructed starting downstream. If funds are not available to complete
the entire project at one time, then the project can separated into the following phases and
constructed in the following order:

1. Riverside Cemetery Construction
2. Channel and Levees downstream of UPRR
3. Pawnee Creek mainstem bridges for HWY 6
4. Box culverts under UPRR embankment at Town of Atwood
5. Channel cleaning and debris removal upstream of HWY 6 mainstem
bridges

IX. DETAILED DESCRIPTION OF SELECTED ALTERNATIVE

Project Location

This study includes the reach along Pawnee Creek from its confluence with the South
Platte River IOO-year floodplain upstream to CR. 29, a distance of about 7.5 miles. Areas
of concern include locations where potential floodwaters exceed the existing Pawnee
Creek channel capacity and damaged farmlands, CRs, and houses. Also of concern is the
Pawnee Creek Overflow where floodwater overtops the channel to the north and
eventually inundates portions of the City of Sterling. In addition to the Pawnee Creek
Overflow, there are areas adjacent to and upstream of CR. 31 where flows overtop the
channel to the south and eventually flow into the Town of Town of Atwood.
Improvements for confining split flow areas to the south were not evaluated for this
study.

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