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A canyon of concrete

By Matthew Roe
New Orleans District
U.S. Army Corps of Engineers

Looking at the U.S. Army Corps of Engineers’ Inner Harbor Navigation Canal Lock from ground level it looks big, but only after descending five flights of scaffolding into the dewatered chamber does the size of the lock come into focus.

The walls climb higher than 50 feet along each side of this 640 foot long canyon of concrete. That is a distance longer than two football fields now silent and empty for a moment on a warm fall afternoon in New Orleans.

Normally the IHNC Lock is bustling with activity, opening and closing more than 30 times daily to move shipping traffic from the Mississippi River to Lake Pontchartrain along the Gulf Intercostal Waterway, but the lock closed Aug. 1 for dewatering maintenance.

“We are bringing the 95 year-old lock into this century,” said Victor Landry, Gulf Intracoastal Waterway operations manager for the corps’ New Orleans District. “Technology has changed so much since the lock was built, but by replacing outdated machinery we are able to extend the life of the lock.”

The lock does not have pumps instead it uses gravity to raise or lower the water in the chamber. The main machinery onsite is used to open and close the gates on either end of the structure. The hand riveted miter gates from the early 1920s have been replaced with modern gates while the massive bull gears and electric motors have been upgraded to hydraulic machinery.

“The old motors and gears were just too difficult to maintain,” Landry said. “When something broke we could not order replacement parts so we would have to fabricate parts or cannibalize old motors and you can only do that for so long. The most significant benefit of the modern hydraulic equipment is that it can be easily repaired and parts are readily available.”

The lock sits on the nation’s third busiest inland waterway the GIWW, running along the Gulf Coast from Texas to Florida, and is a critical piece of infrastructure as it provides the only access point east of the Mississippi River in New Orleans.

Completed in 1923 the Inner Harbor Navigation Canal Lock bears a notable, but scaled down, resemblance to the Panama Canal Locks. The lock is in fact the oldest high traffic lock in the United States and up until this project many of the original mechanisms were still in use.

“The age of the lock did not specifically cause any problems during the dewatering and maintenance project,” said Lynn Tinto, project engineer. “The biggest challenge was incorporating modern gates and machinery into a functioning antique.”

Initial testing of the new systems proved successful but once the lock was rewatered some adjustments had to be made. The New Orleans District was in constant communication with their navigation partners during planning and throughout the dewatering process.

“We had tows queuing up in anticipation of our reopening,” said Tinto. “We had to redirect a lot of traffic for this project, but we now have a much more reliable lock to keep traffic moving on this critical waterway.”

The installation of gates and new equipment required the closing the lock or the duration of the project. Closing a portion of the GIWW required more than three years of planning with the U.S. Coast Guard and the navigation industry.

“We developed the alternate route via the Mississippi River to Bayou Baptiste Collette and across the Breton Sound to the Gulfport Ship Channel to ensure that shallow draft traffic could continue on the GIWW, with IHNC Lock closed for 128 days,” said Landry.

All total the dewatering maintenance cost $20 million which covered the cost of new gates, machinery and labor and material. To the navigation industry though the cost saves them more than the 85 mile detour around to the main stem of the GIWW. The GIWW bottlenecks at the IHNC Lock and if the lock goes down it has far reaching affects. The modern and more reliable machinery now in place at the lock keeps traffic moving through.

“We are salvaging some of the old equipment and recycling the rest,” Landry added. Recycling some of the old gates and parts will generate funds that will be used for future operations and maintenance on the GIWW.

The Corps of Engineers is conducting a study for potential replacement of the old IHNC Lock to accommodate for the size of modern shipping vessels and improve efficiency and effectiveness of passing traffic on this nationally important inland waterway. While the future of the lock is being studied, this current project ensures the current reliability of the old IHNC Lock.

On Dec. 14, through the mist and the fog, the lock was reopened to shipping traffic after sitting empty for months. Tows moving cargo along the GIWW pass through the lock keeping the economy of the region and the country moving rolling along.

The IHNC Lock is one of 11 navigation locks in the New Orleans District. Navigation is only one of the many missions of the New Orleans District. Others include environmental, flood risk management and hurricane and storm risk management. Nationally, the U.S. Army Corps of Engineers operates and maintains 25,000 miles of navigable channels and 196 commercial lock and dam sites and is responsible for ports and waterways in 41 states.