FLOOD09522

• County: Logan
• Community: Sterling, Atwood
• Basin: South Platte
• Title: Pawnee Creek Flood Mitigation, City of Sterling, Town of Atwood and Logan County
• Date: 7/1/1999
• Prepared For: Logan County
• Prepared By: URS Greiner Woodward Clyde
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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SECTIONTHREE Affected Environments and Environmental Consequences

Creek meanders through the project area and transverses Highway 6, the UPRR track, and
several of the county roads.

3.3.1 Alternative 1 . No Action

This alternative would not change existing traffic and circulation within the project area,
including county roads, Highway 6, and the UPRR tracks. However, during major flood events,
the alternative does affect traffic and circulation within the project area. Under existing
conditions, major flooding causes Highway 6 and several county roads to be closed until the
flood flows have subsided. Flooding of these roads frequently results in damage to roads and
bridges, which results in closure and/or restrictive use until the necessary repairs are completed.
Rail transportation is also affected during major flooding events (i.e., when the embankment of
the UPRR track was washed out during the 1997 flood event). This required the closure of
UPRR's main track until necessary repairs could be completed. Both road and rail closures
would continue to occur during major flood events with the No Action Alternative.

3.3.2 Alternative 2 . Improve Routing of Pawnee Creek Flood Flows (Proposed
Action)

Vehicular and rail traffic would be affected by this alternative. Temporary rerouting of vehicular
traffic would be required during construction of the new bridge (northbound traffic) and
construction of box culverts (southbound traffic) at Pawnee Creek on Highway 6. In addition,
traffic on CR 24 would be rerouted while approximately I, I 00 feet of the road is regraded. The
construction of these box culverts would be done by UPRR and they would be responsible for
rerouting train traffic while the box culverts are being installed. This alternative has been
designed such that flood flows would be allowed to cross both Highway 6 and CR 24. During
these events, both roads would be closed to vehicular traffic. Depending on how often this
occurs, this alternative could have a long-term adverse effect on traffic flow. The local
community has stated this effect is acceptable.

The long-term benefits associated with the proposed action include reduced potential that the
UPRR embankment would be washed out during future flood events, reduced damage to county
roads and Highway 6, and reduced period of time that Highway 6 would be closed. Reduced
flooding in Sterling, and to some extent in Atwood, would preclude the closure of several flood-
prone city streets.

3.3.3 Alternative 3 . Pawnee Creek Overflow Cutoff

Vehicular and rail traffic would be affected by this alternative. Traffic on CR 24 would be
rerouted while approximately 1,100 feet of the road is regraded. The construction of these box
culverts would be done by UPRR and they would be responsible for rerouting train traffic while
the box culverts are being installed. The alternative has been designed such that flood flows
would be allowed to cross both Highway 6 and CR 24. During these events, both roads would be
closed to vehicular traffic. Depending on how often this occurs, this alternative could have a

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