N.O. levee inspections fell short of federal mandate
Other engineers incredulous at haphazard examinations
Monday, December 05, 2005
By Bob MarshallStaff writer
Before Hurricane Katrina, levee inspections in New Orleans were so superficial that one engineer who used to work for the Army Corps of Engineers said he conducted more diligent inspections on Florida levees that protected cattle.
Engineers familiar with proper levee inspection routines across the country said the annual tours of New Orleans' vital hurricane protection levees -- described by critics as cursory drive-bys more about fellowship and lunch than looking for problems -- sounded nothing like the serious geotechnical investigations conducted in other places.
Further, the hasty approach taken on the 100-mile, five-hour tours by the Corps of Engineers and its local partners, the Orleans Levee Board and the state Department of Transportation and Development, did not come close to meeting federal regulations.
"Annual inspections take many forms, but any way you slice it, you couldn't inspect 100 miles in five hours -- not properly, anyway," said Thomas Wolff, assistant dean of engineering at Michigan State University and a member of the National Science Foundation team that investigated the levee failures in New Orleans.
"You certainly couldn't meet the requirements by looking down those levees with binoculars from a roadway," Wolff said.
Section 208.10 of Title 33 in the Code of Federal Regulations details how the corps and its local partners must maintain levees and floodwalls. The mandate includes regular inspections to look for encroachments on the levee or its right of way such as fences, patios and pools; the growth of shrubs and trees whose root systems could damage the system's integrity; signs of seepage or sand boils; subsidence; animal burrows; and the accumulation of trash or debris.
A long list of possible problems is spelled out, and inspectors are given a grading system to rank the seriousness of any problems found.
The regulation calls for the thorough inspections to be made "immediately prior to the beginning of the flood season, immediately following each major water period and otherwise at intervals not exceeding 90 days."
Further, in the corps' Flood Control Operations and Maintenance Policies, Regulation 1130-2-530 states, "Projects that protect urban areas or ones where failure would be catastrophic and result in loss of life should be inspected annually." It also tells corps personnel to report nonfederal sponsors who are not complying with the regulations.
Lunch, not levees
Corps and Levee Board officials last month admitted their annual inspections typically were little more than quick driving tours. Inspection of the 17th Street Canal levee usually took place from a stop on the Old Hammond Highway, rather than a thorough walk or drive of the flood control structure that is 15,000 feet long. Records show the inspections were scheduled to end early enough for a taxpayer-paid lunch, costing as much as $900 for 57 people.
The agencies said they conducted more frequent informal inspections, typically when personnel were going to the levees for other purposes. For instance, the Levee Board said it relied on grass cutters to report any problems they might see.
But Wolff, who worked for the corps from 1970 to 1985, said inspections of levees in the districts where he worked, from Missouri to California, were much more formal events. They involved crews of as many as eight engineers who drove and walked the levees, and seldom covered more than 10 miles in a day. He said major inspections of the Mississippi River levees were conducted once every five years, and resulted in written reports, which were used as references before the next such inspection. Less rigorous, but still thorough, inspections were done annually.
"You pretty much physically inspected the entire levee over two days," he said. "Normally that might be as long a stretch as 20 miles. We seldom did more than 10 miles in a day. You couldn't if you were conducting a thorough inspection."
Bob Bea, a University of California-Berkeley engineering professor who was also on the NSF team, said his levee inspections in Florida during a corps career in the 1950s were even more rigorous.
"In some cases we actually came back and did soil borings to inspect suspicious sites," he said. "And those levees were protecting cattle."
Warning signs missed
Bea said careful inspection of the levees was critical because the earthen embankments often hide defects until failure occurs.
"That's one of the problems that plagues engineers in this field," he said. "The levee can look absolutely solid, tall and green and safe. But just below the surface you could have all kind of trouble brewing.
"That's why you have to stay sharp, you can't be complacent. My basic conclusion, based on my experience, is that you can't see something that is impugning the integrity of a levee by looking at it through binoculars from a road."
The engineers agreed that the mistake thought to be at the heart of the New Orleans catastrophes -- sheet piling too short to prevent seepage -- would not have been visible through a walking inspection. And while the use of new, sophisticated ground sonars might have detected weakened soil layers before Katrina, justifying the expense of such a search would have been difficult without evidence, especially in view of recent budget cutbacks.
"But that's why these inspections have to be done conscientiously," Bea said. "You're talking about a system that is supposed to keep half a million people safe."
In fact, investigators now believe there were warning signs that trouble was brewing below the grassy surface of the levees.
Residents living along the 17th Street Canal levee had reported flooded lawns to the Sewerage & Water Board, a problem the Levee Board and Corps of Engineers said they never heard about. Further, NSF investigators said several residents reported other leaks, sand boils and depressions in the levees near the floodwalls -- warning signs that the federal regulations tell the corps to look for in the mandated inspections.
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Bob Marshall can be reached at email@example.com or (504) 826-3539.