A draft environmental assessment for levee repairs along the right descending bank of Big Goose Creek in Sheridan, Wyoming, is currently available for public review, reports the US Army Corps of Engineers, Omaha District.
The draft EA evaluates the environmental impacts of repairing damage to the levee caused by high flows in June 2017.
The proposed repairs include constructing a 100-foot long piggyback levee, removing earthen material and rock from the channel, placing riverside rock rip-rap and geotextile filter and reseeding disturbed areas.
Repairs will be completed under the Corps’ PL 84-99 Emergency Levee Rehabilitation Program.
BACKGROUND
From September 2016 through May of 2017, heavy precipitation fell across a large portion of central and northern Wyoming. The wet autumn and winter months produced a well above-normal snow pack in the region.
The spring snow melt resulted in unusually high flows in Big Goose Creek and produced high soil moisture content. The combination of these factors produced stressful conditions on the levee system.
During the month of June, the highest flows in Big Goose Creek caused a slope failure on the left descending bank of Big Goose Creek which resulted in a considerable amount of sediment and debris to be deposited in the channel.
This, in turn, resulted in a partial blockage of the channel and a redirection of channel flows into the right bank of the creek. The redirected flow eroded approximately 90 feet of the right bank channel slope and riverside levee.
The City of Sheridan responded by dumping heavy, rounded 18-36-inch diameter stone into the scoured area. The stone is considered a temporary repair and does not address the long-term stability or seepage issues that remain.