SEATTLE – The first steps toward repairing the St. Maries, Idaho, levee system kickoff in earnest next week when U.S. Army Corps of Engineers’ officials begin work to repair about 1,810 total feet of levee damage at three sites along the St. Joe River’s left bank.
The $2.6 million federally-funded project is split into two phases, pre- and post-flood season, and will repair seepage and erosion damages from previous flood events. The first construction phase begins Nov. 5, with repairs and risk reduction measures expected to be complete by the end of November.
Repairs at site one, near the 17th Street pump station, include removal, replacement and re-compaction of the levee and shallow foundation to address seepage. Video inspections of pipes running underneath the levees will confirm if they are damaged and contributing to seepage. In addition, because the site is near an EPA Superfund site, ground-water samples will be taken from a test pit as a precautionary measure.
At site two, workers will repair a tension crack, regrade the levee slope and remove excess material to stabilize the slope. Site three repairs will address bank caving as a result of erosion by adding riprap armor to the levee face and extending it to the levee toe. Both sites are located near the Potlatch Lumber Mill.
During the next construction phase, in summer 2013, crews return to site one to replace two culverts beneath the levee and install a 1,500-foot-long seepage berm that will also provide the City of St. Maries with a new widened road.
The Corps coordinated with a number of agencies during the planning, design and construction phases, including: The City of St. Maries; the Environmental Protection Agency; the Coeur d’Alene Tribe; U.S Fish and Wildlife Service; and Benewah County. Collaboration and contributions to the design were provided by the City of St. Maries design engineering firm, Welch Comer.
Once levee repairs are complete, flood protection which had been reduced to a 5-year level will be restored to a 100-year level, meaning a one-percent annual chance of exceedance.