Tale Of The Leaking Levee - NOLA

From NOLA.com:

NEW ORLEANS (AP) -- Despite more than $22 million in repairs, a levee that broke with catastrophic effect during Hurricane Katrina is leaking again because of the mushy ground on which New Orleans was built, raising serious questions about the reliability of the city's flood defenses.

Outside engineering experts who have studied the project told The Associated Press that the type of seepage spotted at the 17th Street Canal in the Lakeview neighborhood afflicts other New Orleans levees, too, and could cause some of them to collapse during a storm.
....

Among other things, they repaired the wall by driving interlocking sheets of steel 60 feet into the ground, compared with about 17 feet before the storm. The sheet metal is supposed to prevent canal water from seeping under the levee through the wet, toothpaste-like soil that lies beneath the city, which was built on reclaimed swamp and filled-in marsh.

Over the past few months, however, the corps found evidence that canal water is seeping through the joints in the sheet metal and then rising to the surface on the other side of the levee, forming puddles and other wet spots.

Bear with me, peeps, while we get into some really technical stuff. No, I am not an engineer. I have no expertise whatsoever in levee design or construction. However, I do have a brain that is, on occasion, functional. We went to Lakeview about a year ago to see the repairs which had been made to fill the gaps in the levees. The repaired portions that closed the breaches were reinforced and built better and stronger than the original levee. However, right alongside the reinforced levee sections were the same old levees of the type that failed. It did cross my mind that what the US Corps of Engineers had done didn't make sense and that the older unreinforced levee sections (which were inadequate during Katrina) right next to the new stronger sections could possibly be weakened by the new construction. Is it possible that no engineer working on the project had this same thought? Perhaps. Or perhaps, if they did, they did not give voice to those thoughts.

The joints! It's the joints! The joints that hold the old and the new sections together leak. They don't hold the water back even when there is no hurricane. There is water on the side that the levees are supposed to keep dry, the part where the houses are.

Next month hurricane season begins, but people of New Orleans, do not worry. Everything is under control.

Donald Jolissaint, chief of the corps' technical support branch in New Orleans, denied the problem at the 17th Street Canal is serious.

"I personally do not at all believe that this little wet spot is anything that is going to cause a breach or a failure of any kind," he said. A newly installed floodgate could be used to cut off the flow of water into the canal and reduce pressure on the levee, he said.

What's a little wet spot? It's not an indication of possible future trouble or anything. But, just in case....

Nevertheless, the corps is concerned enough that for weeks, workers have been analyzing the wet spots and digging a 160-foot-long, 10-foot-deep trench to zero in on the source. "We're doing everything we can to chase this down," Jolissaint said.

Read the comments following the article, and you will see that folks in NOLA don't have a lot of confidence in the Corps.

H/T to Scout at First Draft for calling the article to my attention.