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New Orleans' post-Katrina flood defenses pass big test

Sep 4, 2011, 12:53 p.m.

By Kathy Finn

NEW ORLEANS (Reuters) - New post-Katrina flood protection systems in New Orleans and surrounding areas were performing "very well" Sunday, in what officials said was the first true test since the devastating 2005 hurricane.

Heavy rains and tidal surges from Tropical Storm Lee gave the Army Corps of Engineers a chance to test the full capabilities of crucial new pieces of the system rebuilt after tidal surges during Hurricane Katrina broke through floodwalls along two canals, with catastrophic results.

The Corps closed a massive flood gate and activated an associated pumping system at the London Avenue Canal on Lake Pontchartrain late Friday afternoon.

The London Avenue Canal is one of three outflow canals that move rainwater runoff out of the city and into the lake. As soon as rain begins to accumulate, the New Orleans Sewerage & Water Board activates pumps that push the water outward.

But when tidal surge from the Gulf of Mexico pushes up the lake water level, the surge can force lake water into the canals, which is what happened after Hurricane Katrina.

During that storm, the force of the water into the canals from the lake was so strong that it broke the floodwalls.

The Corps spent billions of dollars rebuilding floodwalls and installing massive flood gates and pumping systems at the London Avenue, Orleans Avenue and 17th Street canals.

Chris Accardo, chief of the operations division in the Corps' New Orleans district, said the London Avenue floodgate was lowered to block the lake surge on Friday when the lake reached a "trigger" level of 2.5 feet and rising.

The new pumps were then activated to move water from the canal through pipes, around the floodgates and into the lake.

"We ran all 20 pumps at one time at 100 percent," Accardo said.

The downpours of Saturday morning combined with the tidal surge pushed the structure to its full capacity, moving 5,200 cubic feet of water per second.

"It was the first time we had a chance to do that. This tropical storm tested our pumping ability at London more than any of the previous hurricanes" since Katrina, Accardo said.

On Saturday, the Corps also closed a massive new floodgate and activated pumps on the Harvey Canal, a wide industrial canal that links into the Mississippi River on the river's West Bank in Jefferson Parish.

Accardo said that structure also operated well.

"It takes a great deal of communication and coordination with Jefferson Parish, the Sewerage & Water Board and the Mayor to do all this, and it's much more of a partnership today than it was before Katrina," he said. "Today, everybody is watching everybody else's back."

As to when the Corps will sound the "all clear" and reopen the flood gates, Accardo couldn't say for sure.

"I'm thinking it will be sometime between Monday and Wednesday," he said.

(Edited by Karen Brooks and Greg McCune)

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