Statements attributed in a published report to U.S. Army Corps of Engineers documents are not substantiated by those documents, a member of an independent review panel who was a main source for the report and a Vicksburg engineer said.

The report says engineers at the Corps’ Mississippi Valley Division headquarters, in Vicksburg, &#8220found and then dismissed” &#8220the engineering mistakes that led to the canal levee failures that flooded most of New Orleans during Hurricane Katrina.”

The report was published a week ago in the New Orleans Times-Picayune under the headline &#8220Corps never pursued design doubts: Higher-ups raised red flag, then dropped it.”

It cites comments from Dr. Robert Bea, a professor at the University of California Berkeley, and correspon-dence between the Corps’ New Orleans District and the division office to which it reports, the MVD.

Bea said the Corps relied on soil-strength data collected and analyzed using methods that were inappropriately risky for the situation and, relying on those methods, used sheet pile that was about half as thick and driven about one-third as deep as it should have been. The pile was driven to about 17 feet when it should’ve been driven to about 50 or 60 feet, Bea said.

Hurricane Katrina struck Aug. 29, driving water over and through multiple structures in New Orleans’ flood-protection system.

The Corps is responsible for the system and has established an umbrella task force, called the Interagency Performance Evaluation Task Force, to investigate what happened. The IPET’s final report is due in June.

Working under and in parallel with IPET to investigate what happened are other, independent, review teams, including one funded by the National Science Foundation.

Bea is a member of that NSF team. He said he expects its work to be complete in February.

The Corps made its most recent major series of upgrades to sections of the system during the 1990s. At least one of those sections, of the 17th Street Outfall Canal, was both upgraded as part of that series and breached by Katrina.

Correspondence on the upgrade design has been compiled as a 286-page, March 1990 design memo. The document is among those being reviewed by investigators and it is available at the IPET’s Web site, http://ipet.wes.army.mil.

The newspaper report says, &#8220Corps documents show the mistake of overly optimistic levee strength was detected by its Vicksburg, Miss., office, which directed local engineers to make changes. But when the chief engineer in New Orleans replied that the results were based on ‘engineering judgment,’ his superiors dropped the issue.”

An MVD civil engineer who retired in 2002 as chief of its geotechnical branch and returned to work in his current capacity following Katrina, Tony Young, said those statements are not supported by the design memo.

The area is built on a former swamp and its soil structure is inconsistent and includes weak layers, including peat, Bea said in the article.

The article says the &#8220mistake of overly optimistic levee strength” is rooted in the collections and analysis methods used on the soil-strength data.

The canal walls of the section were upgraded in conjunction with a canal-deepening-and-widening project of the New Orleans Sewerage and Water Board.

Contracted engineering firms did the soil investigation, taking samples at too-large intervals and at depths biased toward stronger soils, Bea said. The Corps accepted and relied on those measurements and an averaging method that is acceptable for areas with soil layers of greater consistency and strength but is not when considering the foundations of flood-control structures, Bea added.

Young agreed the average is more-conservative than &#8220a strict average.”

&#8220Normally a strength is selected with two-thirds higher and one-third lower,” Young said.

Young said agreed with Bea’s criticism of the way soil-strength data was collected and analyzed.

&#8220I do that when I review things,” Young said of a more-conservative method of taking soil samples, including using &#8220shorter reaches.”

And Young said that Bea’s assignment of blame for the section’s failure to unexpectedly weak soil may prove correct.

&#8220I’m not disputing the possibility that there are weak soils there; I’m just saying it hasn’t been demonstrated,” Young said.

What both Young and Bea agreed is not included in the design memo, however, is any specific estimate of soil strength.

&#8220There is no discussion of specific strength values,” Young said.

The discussion contained in the memo shows the MVD reviewed the New Orleans District’s proposed sheet-pile depth for the upgrade based on a hurricane-protection scenario, of 9.75 feet below sea level.

MVD engineers responded by commenting on the &#8220critical nature” of the project and recommending a more-conservative guideline that would have increased the depth of the sheet pile to between that depth and the 17 feet that was ultimately used, Young said.

The guideline is expressed as a number and an assessment of soil-strength is among the data used to calculate the number.

The district responded with its rationale for using the guideline that resulted in the 9.75-foot depth and the MVD accepted that rationale, Young said.

But the MVD also, however – &#8220and this is a key point,” Young said – recommended that the district study the upgrade as it would be used under normal, non-hurricane conditions. The district’s research into that scenario resulted in requirement for an even stronger wall than that called for by the hurricane scenario using the more-conservative guideline the MVD had suggested, Young said.

&#8220It was controlled by the potential failure of the canal at low water,” Young said of the 17-foot depth that was ultimately used.

&#8220They did what we asked them to do,” Young said of the New Orleans district.

The district’s assessment of the soil’s stability was not questioned by the MVD and a district comment in the correspondence that refers to &#8220engineering judgment” refers to a design issue that is independent of soil strength, Young said.

&#8220There’s been nothing to this point to demonstrate that what was done in the review process was inappropriate,” Young said.

The newspaper report also gives Bea’s estimates of soil strength in the area as 231 pounds per square foot, lower by 149 pounds per square foot than the estimate he says was used by the Corps, 380 pounds per square foot.

Young said his calculations show that based on preliminary data from the investigation that even soil able to support 231 pounds per square foot would have been strong enough to not cause Katrina’s force to breach the wall as it was built. Those calculations suggest that the risk of the wall’s breaching from &#8220deep sliding” due to weak soil, while still possible, may be smaller than Bea suggests, Young said.

Engineers and scientists from the Corps’ Engineer Research and Development Center in Vicksburg are among those on the IPET, MVD regional business director Daniel Hitchings told the U.S. Senate Committee on Environment and Public Works in November.

IPET’s final report is to be reviewed by the American Society of Civil Engineers, of which Vicksburg resident Dr. Bill Marcuson is president.

An additional independent review by the National Academies is due in July. All reports of the reviews are to be made public and investigators’ findings are being applied to repair of the flood-control system as soon as possible, Hitchings told the Senate committee.