This project is being conducted to reduce the risk of flooding in St. Bernard Parish, which is caused by a storm surge that has a 1% chance of occurring annually. St. Bernard Parish is located in southeastern Louisiana, east of and adjacent to the city of New Orleans.

Construction Overview
The work in this 1,911-foot-long reach consists of constructing a cofferdam to a minimum elevation of 7 feet (NAVD 88 2004.65), providing pipes to maintain flow, and installing a new sector gate structure located on the flood side of the existing structure, which was built to an elevation of 31 feet for 2057 conditions. The new sector gate is tied into flood control levees that flank the existing structure by pile founded T-walls, with a sheetpile cutoff wall and scour protection provided at the transition zones. The T-wall transition is tied to two T-walls built on top of the existing earthen levee system to Elevation 29. A control house is being constructed on top of the eastern side of the gate and houses two generators, one primary and one backup. The generator building has a minimum floor elevation of 15.5 feet NAVD 88.

Demolition included the removal of 24-inch riprap both in the channel and on land, the removal of the timber guide wall, and the top portion of the levee. The channel is being excavated and additional excavation is being performed in the cofferdam area in preparation for the cofferdam sheets, 24-inch pipe piles, and the stabilization slab. The completed cofferdam was dewatered. Concrete placement of the stabilization slab followed, as well as installation of rebar for the footer foundation and concrete placement of the footer foundation.

The sector gates were fabricated off-site and barged to the LPV-144 site for installation. The installation included the placement of reinforced concrete following by the mechanical elements, including the pintles, hinges, machinery, and the sector gates themselves. Testing of the sector gates was performed prior to the flooding and removal of the cofferdam.

In preparation for the floodwalls, the ground is being excavated down to the required elevation. Pile driving began after the excavation. Two cofferdams were installed to support the floodwall construction. The cofferdams were dewatered, and 24-inch pipe piles driven. Form work and concrete pours for the stabilization slab, footer, and floodwalls followed.

Prestressed piles and concrete work for the bases of the generator and control houses was completed prior to the installation of preassembled concrete structures.

Final work included the installation of the fender system, dolphins, bedding material, riprap, stone on the protected side, scour protection on the flood side, access roads, and walkways.

Project Highlights

• Installation of a new sector gate, including the pintles, hinges, and machinery
• Construction of two sheetpile cofferdams
• Installation of 24-inch pipe pile
• Tie-in of new sector gate into flood control levees
• Removal of 24-inch riprap, timber guide wall, and the top portion of an existing levee
• Extensive channel excavation
• Construction of new floodwalls
• Construction of generator and control houses