Much Wider Damage to Levees Is Disclosed

The massive levee system protecting New Orleans has sustained heavy damage well beyond the five breaches that are widely known to have caused flooding after Hurricane Katrina, the Army Corps of Engineers said Monday.

Miles of levees that protected the eastern flank of the region, which borders Lake Borgne, washed away in the storm surge from Katrina, which swept inland and caused deep flooding in St. Bernard Parish and the 9th Ward of New Orleans.

Army officials disclosed the destruction of the city’s eastern levee system in a detailed helicopter tour of the region Monday. Unlike some of the levees in New Orleans that continuously hold water back from areas below sea level, these levees exist mainly to repel storm surges.

The loss of the levees has left portions of New Orleans with little or no protection midway through the hurricane season, senior Army officials said. And rebuilding the levees will be a massive undertaking that could take years, meaning the city could be vulnerable for a long time.

“It is gone,” said Col. Richard Wagenaar, the Army Corps’ head engineer for the New Orleans district. “It is literally leveled in places. The power of the surge in this storm was greatly underestimated.”

Wagenaar estimated that 90% of the levee system protecting the region’s eastern flank had been knocked out.

The region is protected by two levees. One is formed by a 17-foot-high barrier along a shipping channel known as the Mississippi River Gulf Outlet. The controversial channel was built in the 1960s and has long stirred the ire of environmentalists and local officials, who say it has made the area more vulnerable to flooding by destroying the natural marshes that can blunt storm surges.

The other, lower levee further inland provides a second layer of defense for St. Bernard Parish and the 9th Ward.

As Katrina approached the Louisiana coastline from the south, it accumulated a wall of water possibly higher than 18 feet. As the storm continued north, its counterclockwise winds pushed the water westward. First, it surged into the bay known as Lake Borgne and then through a narrow barrier island. It next swept across the Mississippi River Gulf Outlet and then encountered the first levee.

Giant sections of that levee are heavily eroded or gone. The levees are made with piled dirt and rock with a steel sheet sandwiched vertically in the dirt. The steel is completely exposed in most of the area and badly deformed.

After sweeping past the levee, Katrina continued inland through a large marsh. Along the way, it deposited more than a dozen large shrimp boats and shipping barges, tossing them like toys.

“I don’t know where those shrimp boats came from,” Wagenaar said, shaking his head. “There are some pretty nice boats down there.”

He predicted that many of the barges stuck hundreds of yards into the marshes would never be removed.

After the surge moved through the marsh, it hit the second levee, the last line of defense for residential neighborhoods. It destroyed that barrier, leaving deep bowls in the dirt where the surging water and waves scoured the soil. It then swept over the suburban neighborhoods on the other side.

The first blocks were heavily damaged or destroyed. An entire row of houses was pushed back a quarter of a mile into the woods. Other houses ended up in the middle of the street. It appears that much of the area will be a total loss, because the damage involves serious structural failures.

Army officials have said repeatedly that the levees and storm walls protecting New Orleans were never designed to handle a Category 4 or 5 hurricane such as Katrina. But now, without any levee system, the city’s eastern flank could be vulnerable even to smaller storms.

It appears that St. Bernard Parish and the 9th Ward were hit from two sides. In addition to the surge from Lake Borgne, water poured through a breach in the Inner Harbor Navigation Channel.

The channel is part of the complex system of shipping, flood control and industrial ports that snakes its way through this city. It connects the Mississippi River, Lake Pontchartrain, the Intracoastal Waterway and ultimately the Mississippi River Gulf Outlet.

Engineers have temporarily patched all five of the breaches in sea walls around the city that are designed to keep water at bay. In addition to the Inner Harbor Navigation Channel, breaches also occurred at the 17th Street Canal and the London Avenue Canal.

Progress is being made in removing standing water from the city. The Army reports that about 6.5 billion gallons are being pumped out each day. Col. Duane Gapinski, who was appointed Sunday to run the “dewatering” team the Army has set up, estimates that the city should be dried out by mid-October at the latest.

Special correspondent Ryan Lillis contributed to this report.