In the last issue I wrote about the state of the US infrastructure and the American Society of Civil Engineers’ report card on the condition of our built environment. One element of that infrastructure-flood control levees-is in the news again, and this time the focus is not just on New Orleans.
Hundreds of communities in the US rely on the protection of flood control structures. The efficacy of that protection is being called into question by a number of sources, from the Federal Emergency Management Agency to the US Army Corps of Engineers. The nature of the problems-and the nature of the potential damage when levees fail-makes this issue more relevant to those of us in the ESC industry than many other pieces of the infrastructure that are constantly being evaluated and marked for upgrades.
We have thousands of miles of levees, many built more than a century ago by railroads, farmers, flood control districts, utilities, and other public and private entities. The standards to which they were built, the materials used, and the maintenance the levees have had-or, in some cases, have not had-are often sketchy.
Why are levees getting so much attention now? There are several reasons. FEMA requires that levees be certified to meet the 100-year flood standard if the areas they protect are to qualify for coverage under the National Flood Insurance Program-a requirement the agency is re-emphasizing as it makes a widespread effort to upgrade its flood maps. Certification is a complex process involving review of design documentation and, especially in cases when that isn’t available, careful studies of the stability of embankments, settlement of the levees, and other characteristics. Frequently it’s not the way the levee itself was constructed but rather the foundation soils-victim to scour erosion, subsidence, seepage, or even burrowing animals-that weaken the structure.
At the same time, the Corps of Engineers has been inspecting levees throughout the country and has identified more than 140 that are at risk of failure in a major flood. As if to underscore these findings, earlier this year a number of levees were breached or overflowed during large storms in Missouri and Colorado. Some states, such as California, have begun inventorying and upgrading their levees, but even special funding approved by California voters in last year’s elections falls far short of what’s required to address the repairs needed in that state. Evaluating the levees will have financial impact-both providing work for those who have the expertise to do the job and potentially diverting funds away from other projects.
Finally, recent precedent holds state government responsible for a levee failure within its jurisdiction, even if the levee was built decades ago by a private owner and the state has had no part in its design or upkeep.
The condition of the levees doesn’t necessarily constitute a crisis-not all problems are equally serious and not all must be fixed at once, as some assessments of the infrastructure imply. However, there is a real need for more information about the conditions and amount of protection our levees provide-in some cases, more information about the number and locations of the levees themselves. Just as stormwater programs all over the country have been inventorying and mapping their infrastructures as part of NPDES Phase II, giving them a better idea of what needs the most urgent attention and where to begin when something goes wrong, so the certification of levees will make maintenance and repair tasks easier when the time comes.
