Saturday, February 9, 2019

Why rebuild the Levees in New Orleans?

There are now a lot of reports on the failures of the Levees in the New Orleans area on the television and on the internet, and now the talk seems to be moving at how much money Louisiana should be given to build more levees around the small isolated communities in the South and to reinforce or rebuild the levees around the New Orleans area. Why do we think that this is a good idea? I am not sure.

From working in this area, I have seen what it takes to build a deep foundation for the mid to high-rise buildings in the CBD, and the one that is certain is that you will be driving piles a few hundred feet to hit anything "substantial" (I use this very loosely) and create enough friction from the surrounding swamp to hold the structure up and create a matt slab to basically float the building. If you have ever lived her or driven around town, you will always notice that the driveways to the residential garages are always a foot or so lower, so that the occupants can not even drive into the garage, and the streets are really bad due to the differential settlement. This is because the land is sinking.

The simple fact is that when you build on a swamp you just don't have a reliable foundation. Now, how far do the sheet piles go down? I am pretty sure that it is not a few hundred feet. No matter what they do to the levees, it will still be like sticking your plastic shovel into the sand at the beach and as we know, once the water gets to it and wets the sand around the shovel, it will fail. Yeah, it is a simple analogy, but it is basically what happened to the levee.

Information on deep foundations and New Orleans:
http://www.eustiseng.com/news.pdf

Information on the Levee:




DRHdesign
http://www.drhdesign.com/

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