The New Orleans levees that ruptured during Hurricane Katrina's storm surges two months ago were weakened by widespread structural flaws, and the construction of several floodwalls may have been undermined by possible corruption, engineering experts told a Senate committee Wednesday.
"We're receiving disturbing reports that there may have been some conscious human error involved. There may have been some malfeasance," said Raymond B. Seed, a civil engineering professor at UC Berkeley who is heading an inquiry financed by the National Science Foundation. "We're pursuing evidence of those stories."
Seed would not detail the allegations. But officials familiar with the reports said the engineering team had heard allegations from contract workers, engineers and others knowledgeable about New Orleans floodwall work that political influence and organized crime might have played a role in construction flaws in at least two levees that failed after Katrina struck Aug. 29.
The officials declined to be identified because the investigation was still in an early stage and the allegations had not been verified.
"These levees should have been expected to perform adequately if they had been designed and constructed properly," Seed said.
The preliminary findings released Wednesday by Seed's team described failures throughout much of the city's levee system and poor oversight by the Army Corps of Engineers and local levee boards (conclusions that were reported earlier by The Times).
The chairwoman of the Senate Committee on Homeland Security and Governmental Affairs, Susan Collins (R-Maine), agreed that the evidence turned up so far pointed to "human error in the form of design and construction flaws, as well as confused and delayed response to the collapse."
Seed's preliminary findings were buttressed by similar comments Wednesday by Peter G. Nicholson, a University of Hawaii engineering professor who heads a separate investigation by a group from the American Society of Civil Engineers.
Ivor van Heerden, a Louisiana State University geologist heading a third inquiry, for the state of Louisiana, also raised doubts about the levees' design and construction.
But Paul Mlakar, a senior research scientist for the Army Corps of Engineers who is heading the agency's internal probe, was reluctant to offer firm conclusions before completion of his investigation, expected in June.
Nicholson said New Orleans levee boards rarely coordinated and instead "did what they saw fit," leading to a hodgepodge of earthen, cement, sand and sheet-metal floodwalls of varying heights and designs.
He said evidence suggested repeated "transition failures," weak links in levee walls where municipalities bordered with each other -- and where gaps in uniformity may have led to erosion and flooding.
At the 17th Street levee, where an early-morning breach Aug. 29 led to flooding in downtown New Orleans and on the city's west side, the floodwall's old sheet-metal underpinnings may have not reached the depths called for by the Army's overall design -- perhaps because of shortcuts during construction of the foundation in the early 1990s.
Seed declined to specify the "malfeasance" alleged, saying he planned to meet with federal officials to request help verifying corruption reports. "We're talking about people who can subpoena things," Seed said.
He said his team had heard troubling reports from "engineers, contractors and, in some cases, from widows" of contractors who worked on levee projects.
Government officials close to the inquiry said Seed's team had requested meetings next week with the Senate committee staff and with the FBI.
The officials said there had been allegations that several construction firms involved in levee work in the early 1990s might have been improperly awarded no-bid contracts because of political connections. There also have been reports of organized crime links to firms involved in the construction, officials said.
"We've heard that inappropriate materials were used during the construction stage," one official said.
After the hearing, Seed said that corps design documents detailed four different depths for sheet piles at one stretch of the 17th Street levee, and that the team had heard allegations that the pilings did not reach the depth specified by corps engineers.
Robert G. Bea, a civil engineering professor at Berkeley and a member of Seed's investigating team, said that the sheet piles, heavy-gauge steel supports, were driven into the foundations of the 17th Street canal to a shallower depth than the design required -- possibly weakening the levee's underpinnings.
The investigators have already determined that the design for the storm walls along the canal misjudged the strength of the soil in the area and that the sheet piles were too shallow. Those design missteps -- which would have been the responsibility of the corps -- could have been compounded by construction firms that further reduced the strength of the levee wall by installing even shorter piles, Bea said.
The London Avenue levee also breached after Katrina. There were separate reports that contractors cut corners in the amounts of dirt used in the levee foundation. One official said the earthen berm appeared to be built up with spongy, substandard "swamp muck" -- perhaps dredged from the levee channel -- instead of dry, compact and less porous dirt fill.
Investigators have found that the fill used at the London Avenue levee was full of "shell material" and sand, both too weak to withstand walls of rushing water when the levees were subjected to the surges during the hurricane.
Design documents for the levees called for stronger dirt fill, Bea said. A photograph taken after the storm and displayed at Wednesday's hearing showed that large quantities of weak fill, mainly sand, had washed away from the levee breach. Evidence suggests the fill material was dredged from the Mississippi River-Gulf Outlet, a waterway that cuts through a former swamp.
Seed said the Army Corps of Engineers fell short not only in its levee design but in its oversight. He said the corps had been weakened by years of budget cuts and an exodus of top-flight engineers.
Corps spokeswoman Carol Sanders said the agency still had "some of the best engineers in the world." She added that she had been unaware of any allegations of corruption in New Orleans levee construction.
"I was surprised to hear that today," she said.