Dive Brief:
- Phase two of the Houma Navigation Canal Lock Complex broke ground on Aug. 7, according to a news release from the Louisiana Coastal Protection and Restoration Authority. Thibodaux, Louisiana-based SeaLevel Construction is building the project, which costs $300 million.
- The HNC Lock Complex is a navigation, flood barrier and hydrologic restoration effort that will help limit saltwater intrusion and distribute freshwater within the Terrebonne Basin, southwest of New Orleans, and protect thousands of acres of wetland wildlife habitat, per the release. It is also intended to facilitate commercial ship travel in the Houma Navigation Canal.
- The new lock will close one of the few remaining gaps of the $6.6 billion Morganza to the Gulf Hurricane Protection system, which stretches for 98 miles and uses levees, floodgates and locks to protect approximately 200,000 residents and nearly 2,000 square miles of land in Terrebonne and Lafourche parishes from storm surge.
Dive Insight:
The HNC Lock Complex will span 110 feet across and 800 feet in length with sector gates on either side, directly adjacent to the existing 250-foot-wide Bubba Dove barge floodgate, according to the release. A braced floodwall will tie the two components together across the channel, and they will work in concert to allow larger ships to pass through the canal.
Project work includes construction of inland and gulf-side sector gates and the lock chamber. It also entails completion of the operations area, the control building and the control building access bridge as well as hydraulically dredging approximately 135,000 cubic yards of material from the HNC to reestablish 15 acres of brackish marsh habitat.
“Today’s groundbreaking brings us one step closer to completing the Morganza to the Gulf system and enhancing the protection against hurricanes and other major storms for the residents of Terrebonne and Lafourche parishes,” said CPRA Chair Gordon Dove in the release.
The first phase, completed in 2022, dredged 1 million cubic yards of material and built 150 acres of marsh in the areas surrounding the complex. A grant from the BP oil spill Restore Act is partly funding the project.
Once complete, the Morganza to the Gulf Hurricane Protection system aims to provide 100-year-flood level risk reduction, protecting the region from a storm surge that has a 1% chance of occurring in any given year, per the project website. Last week the Army Corps of Engineers announced it is starting a comprehensive environmental review of the project to see if further improvements are needed to account for sea level rise and heightened storm effects, which could increase its costs.
