A picture of a section of a failed levee in NO and my take on it.

The decision to and the placement of these barriers to hold back lake Ponchartrain is criminal or if it isn't it should be. The poor people of NO have been sold a 'pig in a poke'. I see a four foot high six inch thick concrete barrier with very little reinforcement between the sections setting on what appears to be little or no footing. wtf

See the one on the other side?

Not as much pressure. Obviously wasn't strong enough to withstand Katrina, but strong enough for the typical canal flows.

I grew up in New Orleans. As someone from there, I don't think we (the "average joe') ever thought of the flooding coming from the canals. In hindsight, that was silly to think that, but it is what we thought.

Could they have been subjected to unpredicted forces once levees had failed?

rain water out of the streets and into the canals, so they weren't used for transportation (the other canal, the Intracoastal Canal, is used for transportation).

I don't think the average citizen thought about lake water being "blown" into the canal by strong northerly winds and vastly increasing the volume of the canal, and thus applying a great deal more pressure to those walls.

Yeah, if they were just for ordinary drainage, I can see how they would be affected by Katrina and the excess lake water.

Just part of the overall system of not being prepared for a hurricane of Katrina's strength or path.

We taxpayers probably paid for a first class levee, I bet a lot of the money went into some contractor's pocket instead of the levee.

but about a month and a half ago someone posted a really sobering set of pictures that compared NOLA's levees to those in Europe. Isn't there a commission out to investigate the Levee Board and Corp of Engineers?

It's bookmarked now - moved from the NOLA area about three years ago - husband is a coonass born and raised there... and there has always been questions on how/why the levees where designed the way they were. :hi:

on how the Dutch have come to NOLA to help with levee rebuilding/planning.

a retaining wall.

:tinfoilhat::tinfoilhat::tinfoilhat:

wide levee? I lived in NOLA in Lakeside for one year, in 93/94. I was terrified every time there was a heavy rain, and it flooded once, but the flooding was 'uptown' and didn't effect Lakeside. People used to joke all the time about the ancient pumps giving out, and the city being deluged by Lake Ponchartrain. They survived the hurricane, but the damn levees broke, and this is exactly what happened. If people were worried about this occurence then, something should have been done long ago to prevent this awful tragedy. Instead, we get serious consideration for the Alaskan highway to nowhere to benefit a very few, while thousands are evacuated from America's most beloved City, many of whom will never return, being either dead or permanently displaced.

:shrug:

6 by 1 foot rather than 4 by 1/2 foot.

Katrina got there.When the hydraulic pressure rose above the center of gravity, it flips. Especially with little or no foundation.No matter the size.

It's too tall vs thick to be 6x1 or 4/1.5 :-)

of the limbs at the end. I don't know like you but to me they look like they are 4 ft x 6 inch with 3/4 chamfer. little or no reinforcement between the sections.

The walls are founded on steel sheet pile. They are cast in sections to control cracking, and reinforcement between sections is not required. Note the rubber/neoprene waterstop visible between the separated sections.

It appears the concrete walls were added to existing levee's in the 90's to provide freeboard, and would probably have been adequate for Katrina's surge west(?) of the Industrial Canal if not for a design flaw/omission in the foundation system. Specifically, the steel sheet pile were not driven to an adequate depth to prevent rotational/sliding failure of the levee system.

My analysis the day of the failure:

http://www.democraticunderground.com/discuss/duboard.php?az=show_topic&forum=104&topic_id=4507221#4507605

Recent article on investigation:

http://www.nola.com/news/t-p/frontpage/index.ssf?/base/news-4/1131604614166260.xml

. . .

Sheet piling -- long, narrow, interlocking sections of solid iron -- often are used to reinforce earthen levees. In the porous, structurally weak soils that are found in the former swampland much of New Orleans was built on, engineers say the longer the pilings, the stronger the wall and the levee.

The New Orleans levees that failed had floodwalls of concrete that sat atop sheet piling walls driven below the tops of the levees. The corps designed and supervised the construction of the floodwalls.

A number of engineering teams investigating the failures said the 17-foot depth of the piles stated by the corps were a critical part of the failure because they did not extend beneath the bottom of the canal, which the corps said was 18.5 feet deep. Water from the canal could quickly move through the porous soils, the engineers said, rapidly reducing the support provided the floodwall and leading to the collapses.

Soil borings the corps consulted as it designed the walls in the early 1990s indicated pilings would have to be driven at least 40 to 50 feet deep before reaching soil strong enough to support the wall, investigators have said.

. . .

Clairity was my original purpose, 'my take'. The good part of DU is you can almost always get to the truth of the matter. :yourock: