The Western Tie-In Navigable Closure Structure project involves the construction of a 56-foot sector gate located on Bayou Verret just south of Outer Cataouatche Canal in St. Charles Parish, LA, south of US HWY 90. The completed sector gate will remain open at all times and only close during storm events to prevent surge. The work consists of constructing permanent access roads, earthen levees, a by-pass channel, T-walls, sluice gates and a sector gate with associated power, controls, and lighting, and temporary retaining structures.

A temporary by-pass channel is being constructed during the site preparation activities. A temporary guidewall and dolphins are installed and the by-pass channel mechanically excavated via a barge-mounted crane.

Sector gate construction includes the excavation of the sector gate housing using a barge-mounted long-reach excavator. A temporary retaining structure (i.e. cofferdam) will be constructed and dewatered. The sector gate foundation and walls will be constructed followed by the control houses, along with associated mechanical and electrical components. The finished sector gate will be delivered from an offsite fabrication shop and lifted and set in place.

The area identified for constructing the sluice gate will be mechanically excavated to remove excess sediments and allow for proper installation of the temporary retaining structure (TRS) according to the design specifications and approved TRS plan. Miscellaneous metalwork needed to install the sluice gates will be placed as required during the construction of the sluice gate structure followed by the sluice gate mechanical and electrical components.

Construction of the west floodwall will begin while the TRS for the sluice gates are installed and being dewatered. Construction of the east floodwall will begin once the sluice gate and west floodwall are complete. Levees will be constructed to tie the existing levees on the eastern and western edges of Bayou Verrett to the final floodwall monoliths constructed.

Project Highlights

• Construction of temporary retaining structures for both the sector gate and sluice gate construction
• Extensive piling operations to support to construction of the sector gate, sluice gates, and the floodwall extensions
• Extensive concrete placement for gate foundations and T-wall extensions
• Construction of levees to tie the existing levees on the eastern and western edges of the Bayou Verrett to the final floodwall monoliths