[StBernard] Levee Design

[Westley Annis]

The Michoud Plant received minimal damage especially compared to St.
Bernard.  One would have to look at the modeling of how the storm surge came
in to really understand everything scientifically.  I have no doubt that the
men who stayed behind to man the pumps had a lot to do with keeping the
plant from suffering severe damage.  
 
Nevertheless, there is a design that takes into account the wave action.  I
worked at the Corps a few years ago and while examining some of the levees
and floodwalls in Kenner, there was one with a concave design.  This was
designed with a storm surge in mind.  I remember talking to the Senior
engineers and they said that the costs were too high to design a floodwall
high enough to counter the modeled storm surge at that particular area.
This particular designed would push the wave back out and knock out some of
the momentum of the surge.  As the sa ying goes, there's "more than one way
to skin a cat".  
 
Michelle

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	Deborah Keller wrote:
	
	Also a factor in levee height is wave run up. In some geographic
areas 
	the Corps assumes that the water will be still, such as an inland 
	canal, and in other areas there would be a wind driven wave running
up 
	the bankline or shoreline, so the levee protection has to be a
little 
	higher to take that into account and stronger to take the force of 
	impact from a wave.
	
	As a civil engineer, I'd prefer if we would all stop talking about 
	categories of Saffir-Simpson and be specific about the actual design

	central pressure, max. sustained wind speed, storm surge, wind 
	pressure, STORM PATH, and SPEED OF THE STORM ACROSS THE AREA.
	
	Also, the creators of Saffir-Simpson said after Katrina, that these 
	were approximations and that perhaps they need to re-think the
numbers 
	that fall in each category. In other words, maybe a Cat 3 storm 
	pro duces storm surges greater t han 18 feet.