Inner Harbor Navigation Canal Floodwall
New Orleans Region ENR Texas & Louisiana
Owner U.S. Army Corps of Engineers, New Orleans
Lead Design Ben C. Gerwick, New Orleans
General Contractor Traylor-Massman-Weeks, Evansville, Ind.
Construction Manager Shaw Environmental and Infrastructure, Baton Rouge
The $330-million floodwall is a key aspect of New Orleans' new Inner Harbor Navigation Canal Surge Barrier, the largest design-build civil-works project in the U.S. Army Corps of Engineers' history. The alignment spans about 7,500 ft, closing off the Mississippi River Gulf Outlet and tying into the Gulf Intracoastal Waterway bypass structure. The 100-year storm-surge design requires protection against a surge of 21.6 ft on the flood side of the wall, plus a significant wave height of 6.7 ft.
The main foundation component is a series of post-tensioned concrete piles—each 66 in. in dia and 144 ft long—that were cast in 16-ft sections. Piles were driven with 6-ft center-to-center dimensions. To create the wall's solid front and rear faces, pairs of 18-in.-square by 59.75-ft-long closure piles were wet-set in 36-in.-dia jet-grout plumes, which closed the gaps between each pair of cylinder piles. To provide lateral support, 36-in.-dia by 248-ft-long steel batter piles were driven in two pieces. Components were then joined with precast and cast-in-place concrete caps and a 2-ft-thick parapet wall. In all, crews installed 4,454 permanent piles; removed 26,000 cu yd of spoil; placed 68,000 cu yd of concrete; injected 530,000 cu ft of jet-grout soil stabilizer; and installed 300 precast cap sections, each 90 tons.
Traylor-Massman-Weeks worked under an accelerated 18-month schedule, proceeding at 30% design and procuring materials in advance of design completion. Work required extensive use of floating equipment and a custom-engineered 2,000-ft trestle system founded on 36-in.-dia by 130-ft steel friction-pile bents. The system required repetitive removal, reinstallation and adaptation to prevent work conflicts and preserve the schedule.
The judges were especially impressed by the "phenomenal amount of work done in the time allotted."