N.O. Levees Installed Correctly
NEW ORLEANS – Eight sections of steel sheet pulled from a failed New Orleans levee Tuesday appear to have been driven into the ground to the specified depth, contradicting earlier tests, engineers said.
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 steel had been sunk into the ground to prevent water from saturating the soil and destabilizing the flood walls. Initial testing by sonar had indicated the sheet pilings were driven to only about 10 feet below sea level, even though the design called for 17.5 feet below sea level.
The discrepancy fueled suspicion of wrongdoing in the building of the flood wall, attracting criminal investigators to the work site. The U.S. attorney, the state attorney general and the district attorney all have launched investigations into the building and maintenance of the levees.
After pulling and measuring the pilings, officials with the U.S. Army Corps of Engineers expressed a measure of relief, since the Corps was responsible for ensuring the construction matched the design when the flood wall was built in the early 1990s.
But if the flood wall was built to specifications, as the latest inspection indicated, the next question will be whether the design was faulty.
"We need to look at all the failure mechanisms because obviously something did happen here and each piece of the puzzle helps us determine what happened," said Col. Lewis Setliff, commander of the task force restoring about 350 miles of hurricane protection levees in the New Orleans area.
Brig. Gen. Robert Crear said the length of the sections pulled all exceeded 23 feet. About six feet of the sheet piling was above sea level, leaving a little more than 17 feet below sea level — in accordance with design specifications.
Engineers also plan to test the concrete and the reinforcing bars in the flood wall to ensure they were made properly.
Also, engineers must try to figure out why the sonar tests yielded bad results on how deep the sheet pilings were driven.