The U.S. Army Corps of Engineers (Corps) Walla Walla District, in cooperation with the project sponsor, Madison County, Idaho, proposes to design and construct a streambank stabilization project on the South Fork of the Snake River between Rexburg and Ririe, Idaho. The proposed design would protect the southern approach to the Archer Highway North Twin Bridge where the river channel has migrated south and threatens to undermine the bridge during high river flow events. The Corps invites public comments on an environmental assessment (EA) which evaluates alternatives for the project and documents the environmental effects of the project. Comments are due by Sept. 3, 2012. The EA will also determine if an environmental impact statement (EIS) is necessary.
Due to changing river conditions, severe erosion is occurring at the North Twin Bridge on the south bank and bridge abutment. This increased erosion threatens the stability of the bridge. The Corps proposes to armor the southern approach of the North Twin Bridge. The armor would span 900 feet along the upstream side of the highway and 100 feet along the downstream side of the highway. In addition, sheet piling would be used to protect the south bridge abutment beneath the bridge.
The public comment period on the EA runs through September 3, 2012. Comments can be emailed to TwinBridgesEA@usace.army.mil: faxed to 509-527-7807; or sent by mail to:
U.S. Army Corps of Engineers
Environmental Compliance Section
RE: Twin Bridges EA
201 North Third Ave
Walla Walla, WA 99362