National Science Foundation's Independent Levee Investigation Team pointed to a test done twenty years ago that shows the soil conditions in south Louisiana were inadequate to support floodwalls like the ones built at the 17th Street Canal.
On Friday, the Corps task force set up to investigate the failures reported that the breach at the 17th Street Canal was the result of water working its way in between the floodwall and the earthen levee into which it was set, and of soft subsurface clay. Once the levee split, the force of the high water pushed the floodwall, and the half of the levee behind it, backward on the clay, the corps task force said.
The corps called it an unforeseen combination of events that split the earthen levee and toppled the floodwall.
But Raymond B. Seed and Robert G. Bea, in charge of the National Science Foundation's Independent Levee Investigation Team, said Monday that the results should have been foreseen, given the results of a 1985 test done near Morgan City in south-central Louisiana. The test was done at an Atchafalaya Basin levee and floodwall system built to test whether a design similar to that of the 17th Street Canal levee and floodwall would work.
The test ended when â€” with water nearly 8 feet high along the test floodwall â€” sheet piles supporting it inside the levee began tilting backward, "indicating that failure was imminent," the statement said.
"Not only did they have that in their repertoire of information, they failed to use it, as best we can tell," Seed said in a telephone interview from the University of California at Berkeley.
A spokesman for the Corps of Engineers, shown above, gave the Corps response. "D'oh!"