Water/Environment Best Project: Mississippi West Bank Vicinity Hurricane and Storm Damage Risk Reduction
West Bank and Vicinity Hurricane and Storm Damage Risk Reduction, Mississippi River Levee
Plaquemines Parish, La.
Owner/Lead Design/Civil/Structural: U.S. Army Corps of Engineers (USACE), New Orleans District
Local Stakeholder: Plaquemines Parish Government
General Contractor: Conti Enterprises Inc.
Subcontractor: Nairn Concrete Services
As one of five projects that are part of the Hurricane and Storm Damage Risk Reduction program, the West Bank and Vicinity project improves hurricane and flood-control protection, decreasing the potential for damage in New Orleans and the surrounding parishes.
This 1.5-mile-long segment of the Mississippi River levee system, which tied into the WBV-MRL 5.2 and 3.2 contracts that were occurring concurrently, was the most complex due to its concrete floodwall components. The other contracts involved constructing only earthen levees. But on this project, crews built a new 7,100 linear ft levee with a 6,600 linear ft concrete floodwall along the Mississippi River with an elevation of 24.5 ft. In total, the project team placed 44,000 tons of concrete across walls and footings.
The construction was technically complex, encompassing dangerous operations and requiring constant coordination with the key stakeholders, local businesses and residents. To drive 100-ft-long steel-pipe piles for floodwall support, the contractor worked directly with the local utility to schedule outages and temporarily restrain power lines so the team could pile-drive below them. Crews were permitted 10 days for this operation and effectively completed the work in four.
Frequent rain brought nearly five high-river occurrences to the jobsite, seriously delaying the schedule. Contractually, crews were required to stop work when river elevations rose above 11 ft, so the team battled flooding with effective staging and received approval to work on three 500-ft sections of floodwall at once. During floods, the project team resequenced work to focus on other approved locations.
In anticipation of high-river events, and to reduce the impact of minor flooding, the contractor requested and received approval to continue pile-driving with river elevations up to 13 ft, and to perform concrete work up to 15 ft, to avoid delays. The schedule was tested as the river reached a flood-stage elevation of 17 ft, but the project team resumed work immediately once water levels receded.
Given the project’s urgency, Congress fully funded the program up front, allowing USACE to begin contracting immediately.
Related Article: Diverse Projects Named Region’s Best