Warning Sounded About Levees
Wednesday, March 8, 2006
An expert panel monitoring reconstruction of New Orleans's hurricane-protection system warned federal engineers last month about the presence of weak, sandy soils in a newly rebuilt levee, the panel's leader said yesterday, escalating a dispute over the soundness of the government's rebuilding effort.
Raymond Seed, an engineering professor at the University of California at Berkeley, also disclosed new details about what he described as serious flaws in the Army Corps of Engineers building practices. Seed said the problems were observed in at least three locations along an 11-mile earthen levee near Lake Borgne, east of New Orleans, that was nearly washed away by Hurricane Katrina on Aug. 29.
"A growing chorus of experts are trying to tell you that there may be some significant concerns with regard to the materials" used in rebuilding the levees, Seed said in a letter to Lt. Gen. Carl A. Strock, the Corps' commander. "These same levees eroded catastrophically during Katrina, and were the principal source of the massive flooding" of neighborhoods east of downtown New Orleans.
Corps and White House officials disputed the findings by Seed's group and another expert panel monitoring the rebuilding. Strock specifically sought to rebut the groups' conclusions at a White House news conference Monday, saying Corps engineers were "giving tremendous scrutiny" to construction practices.
"We are using the right material," Strock said, "and we're putting it down the right way."
The Corps is attempting repairs to more than 160 miles of levees and floodwalls damaged by Katrina. The Bush administration has pledged to rebuild the levees to their pre-Katrina height before June 1, the start of the next hurricane season.
Seed's group, an engineering panel funded by the National Science Foundation, and a separate Louisiana panel of experts have questioned the reconstruction effort, saying the Corps is misleading state residents into believing the levee system will be safe by summer.
In the letter, Seed said he and another Berkeley engineer personally observed Corps contractors constructing a section of the levee using "clean, fine grained sand, which is highly erodeable."
When the problem was pointed out, a Corps officer ordered the contractor to remove the material, Seed wrote. But later, at a different site a few miles south, the engineers discovered and sampled more sandy material. Lab tests confirmed the presence of "highly erodeable clean sands along major stretches of these evolving levee embankments," Seed wrote.
Seed said Corps officials at the site acknowledged the problem and "were, in fact, eager for advice from us." The officials wanted to know how "they might, later, provide some measure of slope face protection to mitigate what they admitted was an unsafe condition," Seed wrote.