NEW ORLEANS—The Army Corps of Engineers proposed in the 1980s placing "butterfly" gates at the mouths of three critical New Orleans canals to stop a storm surge from entering them from Lake Pontchartrain, but local officials rejected the idea, according to the corps' top official in New Orleans and newly released documents.
The proposed gates would have automatically closed when the lake level was higher than the water in the canals, and probably would have prevented the kind of flooding that inundated most of the city through breaches along the 17th Street and London Avenue canals, engineers say.
But local officials feared that the gates would prevent the canals from being used to pump rainwater out of the city—a more common occurrence—and instead adopted the system of steel and concrete floodwalls that failed disastrously on two of the three canals as Hurricane Katrina raced by New Orleans Aug. 29.
The disagreement between the corps and local officials underscores the complexity of the relationships—and priorities—that govern the design, construction and maintenance of the network of canals and levees that protects New Orleans from flooding. And it raises anew questions about whether the rebuilding of New Orleans ought also to include revamping the complicated governance system that gives federal, state and local agencies often competing responsibilities for the canals.
Investigators are expected to offer their first public assessment of who is to blame for the floodwalls' failures at a hearing Wednesday in Washington, D.C., of the Senate Homeland Security and Government Affairs Committee. On tap to testify are members of two groups of engineers, one sponsored by the National Science Foundation, the other by American Society of Civil Engineers, who have been conducting a joint inquiry into the disaster.
It is unclear whether the issue of competing government agencies will be raised, but several investigators have said they found numerous weaknesses in the levees caused by different types of construction overseen by different government agencies.
While the corps' gate proposal had as its goal preventing the kind of flooding that took place during Hurricane Katrina, local officials were more concerned with making certain heavy rains didn't leave standing water in the streets. Local officials felt they could accomplish the same thing by so-called "parallel protection" system—building tall concrete walls atop the canal's earthen levees.
At the time, the Water Resources Development Act of 1986 had recently increased the share local governments had to chip in for flood control projects and had shifted to the locals the costs of maintaining and operating the projects after the corps completed them.
That gave the local agencies not only a bigger stake in the projects, but also a bigger say in what was built.
The corps eventually agreed to support the locally favored plan for the 17th Street Canal. But it continued to oppose parallel protection for the London Avenue and Orleans canals, and never budgeted money for them. That forces the local districts to go to Congress each year for money for the walls that ultimately were built along those canals.
Col. Richard Wagenaar, head of the corps' New Orleans District, said the corps shares responsibility for building the floodwalls that failed, but that local officials determined what type of flood control system would be used.
"The public believes we are the total controllers of all this and we are not," he said.
Wagenaar's emphasis on the local agencies' control of the levees comes as investigators are raising troubling questions about the design and construction of the floodwalls along the London Avenue and 17th Street canals, where breaches allowed most of the flooding of New Orleans.
Weak soil beneath the levees is the chief suspect in the failures, and investigators are trying to determine whether steel piling that formed the floodwalls' core was driven deep enough into the levees to block water from traveling under the walls.
Documents released Saturday by the corps show that that as early as 1982, soils experts retained to analyze the effects of proposed dredging were worried about buried beach sands beneath the canal. By 1985, further testing allayed these concerns. The canal was eventually dredged to a depth of 18.5 feet when the floodwalls were built in the 1990s.
Robert Bea of the University of California at Berkeley and a member of a National Science Foundation joint team investigating the canal failures during Hurricane Katrina, said that the report shows engineers "identifying very early on concerns for seepage. Those concerns surfaced during Katrina, and from everything we can tell are responsible for the failure at the 17th Street Canal and London Avenue Canal."
But determining where fault lies has been difficult. Though the corps usually designs and builds the levees, local districts also can hire engineering firms and construction companies, as they did for the 17th Street, London Avenue and Orleans canals.
Although located in Jefferson Parish, the 17th Street Canal itself is owned, maintained and operated by the Sewerage and Water Board of New Orleans; the floodwalls on the east bank are the property and responsibility of the Orleans Levee District, and the west bank is part of the East Jefferson Levee District's flood control system, according to corps documents.
The local districts are politically formidable. Many have existed for 100 years, with members who are appointed by the governor, legislature, city council or are directly elected. Some have their own taxing authority; some report to local parish councils or the city council while others are responsible to the state, which passes federal funds to them through the state's Department of Transportation and Development.
The system "sets up situation where you have a large overshadowing federal agency providing the bulk of the financing, then you have smaller local entities trying to be sensitive to the wishes of the community," said Mark Lambert, spokesman for the state Department of Transportation and Development.
In the case of the 17th Street Canal, the Orleans Levee District hired a private engineering firm to design the floodwalls. A different local firm under the direction of the New Orleans Sewerage and Water Board drove the steel piling that the floodwalls sit atop. A third local company built the floodwalls themselves—this time, under the direction of the Corps of Engineers.
The corps also conducted its own soils tests, twice reviewed the design in 1992 and issued the construction permit A similar arrangement governed the construction of the London Avenue Canal's floodwalls.
But the floodwalls weren't the corps' preferred plan, Wagenaar said.
Instead, the corps favored so-called "fronting protection"—gates at the mouths of the canals that could be closed during a hurricane, keeping Lake Pontchartrain's flood surges from entering. The gates were designed to sense the direction of flow in the canal and automatically close if water began entering the canal. The gate would remain closed until the lake waters receded.
The Orleans and East Jefferson levee districts and the Sewerage and Water Board of New Orleans opposed that proposal, but the corps insisted on it until 1990, when it relented on the 17th Street Canal after a cost analysis found no appreciable savings attached to the gates proposal.
The corps held firm on the other two, however, forcing the local districts to take their arguments for the floodwalls to Congress. When the 1990 federal Water Resources Development Act was passed, a legislative conference committee directed the corps to proceed with the floodwalls, according to a corps document.
But the corps still refused, taking the position that since the directive was not in the 1990 legislation, but only in a conference committee report, it was not bound by it. Each year, the corps budgeted $0 for construction of the London Avenue and Orleans canal floodwalls. Congress then attached an annual appropriation for the project to that year's budget.
"At end of the day, it's their canal, their construction, and that led to the parallel protection deal," Wagenaar said.
(Carey reports for the San Jose Mercury News.)
(c) 2005, Knight Ridder/Tribune Information Services.
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