Floodwalls' collapse in New Orleans linked to soil failure

Knight Ridder Newspapers
Oct. 08, 2005

Hurricane Katrina's storm surges were never high enough to go over the walls of two canals whose failure caused massive flooding in western and central New Orleans, investigators have determined.

The finding appears to eliminate an early theory about why walls failed along the 17th Street and London Avenue canals: that the concrete and steel walls were topped by floodwaters, which then scoured out the soil in back of the walls, leading to their collapse.

A team of engineers instead found evidence of a massive movement of the embankment underneath sections of the floodwalls. The water pushed one section of the 17th Street levee back 35 feet.

Why the soil failed remains "a mystery story" awaiting further investigation, said Raymond Seed, a civil-engineering professor from the University of California, Berkeley.

Adding to the mystery, the floodwalls along the nearby Orleans Canal made it through the storm intact, even though they were subjected to similar surges of water, and the floodwalls on the other two canals broke in only three places, he said.

Investigators were unwilling to say whether construction or design flaws contributed to the collapse, noting they needed more time to study documents and blueprints. Investigators have not been able to examine the "as-built" drawings that would show the depth of the steel piling inside the walls and other construction details, Seed said.

The collapse of the floodwalls on the 17th Street and London Avenue canals is of particular interest because most of New Orleans' flooding was caused by water flowing through those breaches.

The investigators also said they had eliminated one widely reported theory that a drifting barge was responsible for a breach in the floodwall along the Industrial Canal, flooding New Orleans' Ninth Ward.

Investigators said they had confirmed that a barge struck the canal's floodwall. But they said the point of impact occurred at the southern end of the breach and could not have been responsible for it.

Seed leads a team funded by the National Science Foundation. It was joined by a team from the American Society of Civil Engineers. The U.S. Army Corps of Engineers is assisting in the investigation.

The concrete and steel floodwalls that line the London Avenue, 17th Street and Orleans canals leading into Lake Pontchartrain were built atop levees in the mid-1980s to add more flood protection to the canals.

Seed said the investigation should enable the Corps of Engineers to rebuild the levees stronger than they were and design a system to protect the city from storms stronger than Katrina.

Gambling

Mayor betting casinos would help economy

NEW ORLEANS — Mayor Ray Nagin yesterday said he wants to allow Las Vegas-style gambling in the city's larger hotels to jump-start the economy after Hurricane Katrina.

The plan calls for a large-scale gambling area in the city's central business district. Nagin said gambling should be allowed in hotels that have more than 500 rooms, the majority of which are near the city's famed Canal Street. The plan would require legislative approval.

Gambling already is allowed using video machines in about half of Louisiana's 64 parishes, but there's only one full-scale, land-based casino, operated by Harrah's Entertainment, in New Orleans. Harrah's downtown casino has been closed since shortly before Katrina hit. Also, three dockside riverboat casinos operate in the New Orleans area.

Harrah's spokesman Alberto Lopez declined to comment on the proposal.

Police

Auto dealership break-in investigated

NEW ORLEANS — State authorities are investigating allegations New Orleans police officers broke into a dealership and took nearly 200 cars — including 41 new Cadillacs — as Hurricane Katrina closed in.

"It is a very, very active investigation," Kris Wartelle, spokeswoman for the Louisiana attorney general, said yesterday. "We expect developments quickly."

Wartelle would not comment on why the officers may have taken the cars or whether they were used in the line of duty. However, the cars may have been taken before the hurricane roared into town Aug. 29, according to Doug Stead, the president and general manager of the dealership.

"We put the loss on new cars at $3.7 million," Stead said. "The used cars ran another $900,000."

Safety

Global Limo buses ordered off the road

DALLAS — Federal officials yesterday ordered the immediate shutdown of Global Limo, which operated the bus involved in a fire last month that killed 23 hurricane evacuees along a Texas highway.

The Federal Motor Carrier Safety Administration said it ordered the company off the road because the conditions of its vehicles and drivers "are likely to result in serious injury or death."

Global operated the bus that caught fire near Dallas on Sept. 23 after leaving Houston with nursing-home residents who were fleeing Hurricane Rita.