I asked Don, the Contractor, who sits in the same coffee shop in which I edit papers and code, to read the comments from this blog re the failure of New Orleans floodwalls.
I had thought some of them quite good, so I was shocked when Don finally finished and said "Bullshit," which was the strongest language I had ever heard him use.
He did not like the attempts to pin blame on someone. He skipped over the contractors who built the walls and said that the mistake was to put the walls there in the first place. They were built on silt. Water can leak through silt and, as it flows, widen the pathway. In effect, he predicted that the dirt base of the floodwalls had been eaten out from below.
Don has only a high school degree, but knows how to understand how things work. He makes a good living running his own small business. He grew up in New Orleans and has been down there to look around. But, he is no civil engineer.
The next day, a team of Civil Engineers agreed with Don.
The dirt base of the walls seemed to have been undercut. The entire structure, dirt and wall slid sideways. There still seems to exist, as someone here has pointed out, the possibility that the design was not followed - that it demanded a deeper structure than was actually built. Don seems to wonder how deep into silt would be deep enough.
Don said that the barge had no signs upon it that it had banged forcefully against a wall. Even had it been pressed against the wall by the rather mild (under 120 mph) winds, that would not cause 400 feet or so of dirt, steel and concrete to slide sideways?
Thanks for the ideas. Unlike Don, I found them interesting, teaching me more than I had known.
1 hour ago