Bayou Chene Flood Protection Structure

Location
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.

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.

In 2019, at the request of Governor John Bell Edwards and officials at CPRA, the levee district installed the emergency structure again.  This decision was made because with already elevated water levels and an anticipated opening of Morganza, the flooding could be devastating.  The structure was installed utilizing material from the 2016 closure and was completed in 7 days.  Within a matter of days of completion, areas that were already flooding experienced relief from the high river.

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 +10.0’
• 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 currently 95% complete.

 

Construction Cost Estimate
Permanent Structure $80,000,000
Permanent Structure Project Schedule
In February of 2019 Governor John Bell Edwards announced that The Coastal Protection and Restoration Authority (CPRA) using Gulf Of Mexico Energy Security Act (GOMESA) funds would fund the entire $80 million project that is the permanent Bayou Chene structure.  The project has been phased out for bidding and funding purposes.  Phase 1A, Clearing and Grubbing of Tabor canal was completed in mid November.  Phase 1B, Dredging and spoil placement for new the new levee on Tabor Canal will begin in mid December 2019.  Phase 2, flood wall and receiving structure should be bid out in early December of 2019.  Phase 3 will be bid out shortly after Phase 2.  Phase 4, earthen levee completion, is expected to be completed in the first half of 2022.  You can see the schedule below.

How and Why The Bayou Chene Project Works

2019 Emergency Structure

Current Activities