In this forum of informed minds, is there anyone who can find the latest theory on the failure of flood-wall on the 17th Street Canal in New Orleans? This failure seems to have been responsible for most of the flooding in the city.
The theory favored by the Corps of Engineers, which had the virtue of both exonerating it and providing it a chance at more funding, was that the storm-surge topped the wall, and, falling behind it, washed away supporting dirt covering the base, or the steel supports of the base, of the wall. One problem faced by this theory seems to be lack of evidence that the canal's water got within two feet of the top of the wall. The solution to this detail has been that a short-duration surge might not leave any direct evidence. I do not know anyone personally who actually believes such a thing, but the Corps seemed to be sticking to it as recently as a few days ago.
My own favorite theory of the moment is that a large Boh Brothers barge which was parked in the canal (?!) was forced by water or wind against the wall. The mooring of the barge could have allowed one end of the barge, and not the other, to press against the wall. This could have concentrated the force on a small part of the wall. A 100 mile per hour wind pressing on a large, empty barge sitting high, might create enough additional force to exceed design specks? Or, a heavily loaded barge (getting facts about the barge seems nigh impossible ... and this might itself have an interesting reason) propelled by the wave, if there was such a thing, of the storm surge, and swung laterally by a mooring, might have struck the wall with enough force to crack it.
Additionally, given that we are in Louisiana, I have wondered about sloppy construction. The design of the wall might have been good, but the contractor might have been a nephew of the governor, for example, and willing to cut corners. My theory is that the barge cracked the wall, water came through, washing away supporting the dirt berm which had not been built to proper specs, and the wall slid sideways (as photos show that it did). By the way, the barge is sitting among ruins of houses in the Ninth Ward.