There has been a controversy brewing in New Orleans over the length of the sheet pilings under the floodwalls that gave way. Sonar tests indicated that while the Corps’ plans called for the sheet piles to go down to 17.5 feet below sea level, they were apparently only 10 feet down.
Rather than speculate, they yanked a “good” section (term used euphemistically) section of the wall out the ground and measured the sheet pilings.
NEW ORLEANS (AP) — Four sections of steel sheet piling pulled from the ground Tuesday during an inspection of a failed New Orleans levee appeared to meet design specifications for size and depth, contradicting earlier tests.
The sheet pilings were removed as part of an investigation into why the flood wall at the 17th Street Canal failed, contributing to floods that covered 80 percent of the city when Hurricane Katrina struck on Aug. 29.
The findings were significant because initial testing by sonar had indicated the piling was only driven to about 10 feet below sea level.
If the flood wall was built to specifications, the next question will be whether the design was faulty.
Brig. Gen. Robert Crear of the U.S. Army Corps of Engineers said the length of the first section removed varied from about 23.5 feet to 23.6 feet. About six feet of the sheet piling was above sea level, leaving 17.5 feet or more below sea level — in accordance with design specifications. Three other sections were of similar size and depth, officials said.
LSU computer models showed that even if the pilings had gone to 17.5 feet below sea level as design documents said they should have, they still would have failed because the canal ran deeper and seepage into the ground still could have undermined the flood wall.
To be sure there, neither answer (10 ft pilings or 17.5) was going to be GOOD news for the Corps. But if the pilings were 10 feet they could claim they “only” failed to manage the contractor… The Corps was holding its breath hoping for 10 foot pilings so they could point to the contractor(s).
From these results it looks like the contractors built it EXACTLY the way the Corps designed it. One of the last scapegoats the Corps had has left the barn.