Bayou Chene Flood Protection Structure
St. Mary and Terrebonne Parishes, Louisiana, south of Avoca Island
Latitude 29°37’20.98”N Longitude 91°5’36.31”W
Scope of Work
In May of 2011, the St. Mary Levee District (SMLD) was faced with unprecedented high water elevation predictions threatening St. Mary, Terrebonne, Lafourche, St. Martin, Assumption and Iberville Parishes. SMLD constructed a temporary flood protection structure consisting of a barge floodgate, sheetpile floodwalls, rip rap, and hesco baskets to prevent the areas from flooding. The structure withheld an additional 3’ of water from the parishes mentioned above.
With the success of the temporary 2011 project, SMLD procured and contracted with APTIM in 2012 to design a permanent structure in Bayou Chene south of Amelia, Louisiana. The project is currently being designed for backwater flooding with the following features:
• Steel receiving structure +8.0’ and flood gate, +10.0’, 400’ opening
• Braced steel sheet pile floodwalls to elevation +8.0’
• Elevate the existing Avoca Road to elevation +8.0’
• An earthen levee from Avoca Road to the Structure along the existing borrow canal to elevation +8.0’
• An earthen levee with geotextile fabric from the south side of the closure structure to Tabor Canal to elevation +8.0’
• Earthen levees along Tabor Canal utilizing the existing berm and geotextile fabric to elevation +8.0’
• A weir structure at the end of Tabor Canal to an elevation of +6.0’
The design of the permanent structure is in the permitting phase.
In 2016, another high water event in the Atchafalaya River threatened the surrounding 5 parish area. APTIM was contracted to design an emergency structure to prevent backwater flooding. The structure was designed, bid, and constructed in 15 days, utilizing existing wing walls from a previous flood fight. The emergency structure was left in place until the removal was advertised in July 2016 due to a greater than 1’ water differential between the protected and unprotected sides.
Construction Cost Estimate
Permanent Structure $80,000,000
Permanent Structure Project Schedule
The 5% Design Report was completed in December 2015. The DNR permit was obtained in 2015, and the USACE permit was issued in October of 2018. Design will begin late 2018.