"Bob S." wrote:


This is fascinating. So the land keeps sinking and the buildings just
go down too. So th whole city is just built on washed down junk
(mostly sand I suppose). So, adding fill only compresses the silt
more. This is most interesting. I dont think it should be rebuilt
either, at least not at that location.
Mark

What is facinating is to see how they deal with it. For the
construction of large buildings, they drive pilings into the ground
until they reach solid subsoil. At the New Orleans airport, I've seen a
pile driver drive a 30' telephone pole flush into the ground in 3
licks! They tie on a new pole and keep driving, continuing the process
until they get to about 1ft per lick. There may be 50-100 of these
piling stacks under each foundation.
So if a treated piling has a 50-70 year life span, all these buildings
are eventually going to sink into the muck.
And don't forget about New Orlean's cemetaries. They have to use above
ground crypts because being below sea level, the water table will float
caskets out of the ground.

Really nothing all that fundamentally different than in many locations
where buildings are on loamy or other non-loadbearing soils over solid
subsoils. And, there are other locations where water tables are so high
as to preclude below ground artifices of many sorts. It's just that NO
is a more extreme example than the rest of us are used to.