Bayou Chene Floodgate Structure
APTIM's Coastal, Ports, and Marine team helps to protect 30,000 coastal residents with Bayou Chene Floodgate, the largest of its kind in the world.
In May of 2011, rising water levels in the Mississippi River threatened the heavily populated cities of Baton Rouge and New Orleans, Louisiana, and the surrounding communities. To alleviate downriver mainline levee stress and to lower risks of levee overtopping, the United States Army Corps of Engineers (USACE) opened the gates of the Morganza Flood Control Structure located at River Mile 280 in central Louisiana.
While diverting a sizable volume of water from the Mississippi River into the Atchafalaya Basin assisted in preventing flooding downriver from the Morganza Flood Control Structure, the additional water in the Atchafalaya Basin threatened St. Mary, Terrebonne, Lafourche, St. Martin, Assumption, and Iberville Parishes. To combat this threat, the St. Mary Levee District (SMLD) constructed a temporary flood protection structure in Bayou Chene consisting of a barge floodgate flanked by sheet pile floodwalls with riprap armoring and Hesco™ basket “levees”. The temporary effort prevented approximately 5’ of water from flooding the affected parishes. In 2016, a high water event in the Atchafalaya River threatened the surrounding 5 parish area. Aptim Environmental & Infrastructure, LLC (APTIM) was contracted to design an emergency structure to prevent backwater flooding from the Atchafalaya River. The structure was designed, bid, and constructed in 15 days, utilizing existing wing walls from a previous flood fight. The emergency structure was again successful in holding back approximately 2’ of flood water.
In 2019, a high-water event in the Atchafalaya River paired with the imminent opening of the Morganza Control Structure again threatened the surrounding 5 parish area. APTIM was once more contracted to design an emergency structure. The structure was designed, bid, and constructed in 11 days. The Terrebonne Levee & Conservation District (TLCD) and the Southeast Louisiana Flood Protection Authority – West (SLFPA-W) provided SMLD with support, labor, and materials.
Following the proven success of these interim emergency projects, SMLD retained the services of APTIM and a team of subconsultants including T. Baker Smith, Inc.; Miller Engineers and Associates, Inc.; and Eustis Engineering Services, LLC to permit and design the Bayou Chene Flood Protection Structure (BCFPS). As part of this program, a floodwall, gate structure, and levees are proposed in and surrounding Bayou Chene that can be closed to stop the backwater flooding that travels northeast from the Atchafalaya River during high water events in the Mississippi River and Tributaries (MR&T) system. All elevations (EL.) referenced herein are North American Vertical Datum of 1988 (NAVD88) unless otherwise noted. The BCFPS Project consists of the following:
- Steel receiving structure (to EL. 10.0) consisting of braced steel frames on vertical pipe piles, cutoff walls and landing piles to provide lateral and vertical support of the gate in the closed position. Clear opening of 403’ is provided.
- Swing barge gate that is 446’-6” long by 80’ wide by 29’ high with a 5’ high wall to EL. 10.0’ in the closed position
- Braced steel sheet pile floodwalls (to EL. 10.0’) with one waler braced by vertical and battered piles
- Avoca Road raised to EL. 8.0’
- An earthen levee to EL. 8.0’ from Avoca Road to the north side of the closure structure along the existing borrow canal
- An earthen levee to EL. 8.0’ from the south side of the closure structure to Tabor Canal
- Earthen levees to EL. 8.0’ along Tabor Canal utilizing the existing berm
- A sheet pile wall to EL. 8.0’ at the end of Tabor Canal
The project was divided into five primary phases as indicated in the list below. Due to the emergency structure being in place upon initiation of Phase 1 construction, Phase 1 was split into 2 phases – Phase 1A and 1B. Phase 1A consists of the clearing and grubbing along Tabor Canal and Phase 1B consists of dredging Tabor Canal. Phase 4 was also split into 2 phases – Phase 4A and 4B. Phase 4A consists of surveying, clearing, and grubbing along Avoca Road and Phase 4B consists of elevating the Tabor Canal Levee to EL. 8.0’.
- Phase 1A: Clearing and Grubbing along Tabor Canal
- Phase 1B: Dredging, first lift of South Levee Tie-in and Tabor Canal Levee, and a Shoreline Protection Dike
- Phase 2: Receiving Structure, Floodwalls, North Levee Tie-In, Guidewalls, and Demolition of the Existing Structure
- Phase 3: Floodgate, Pivot Pile, and Mooring Structures
- Phase 4A: Avoca Roadway
- Phase 4B: Tabor Levee & Weir
- Phase 5: Shore Power
On April 29, 2022, a ribbon-cutting ceremony was held to signify the completion of the Bayou Chene Floodgate Structure.
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