As rescue workers continue the grim search for bodies in New Orleans, environmental engineers are struggling with what will probably become the biggest challenge of Katrina -- the mess. A toxic brew of oil, chemicals, bacteria, debris, and garbage must be cleared and the ground scrubbed before the city can be rebuilt. Unfortunately, the experts have few new ideas about how to tackle a cleanup of this scale. "There is no silver bullet, and I would be highly suspicious of anyone who says there is," says Calvin H. Ward, an environmental engineering professor at Rice University.
Federal and state scientists have started surveying the many cleanup issues. Those assessments are expected to take months, but the Environmental Protection Agency has already found that the floodwater pumped back into Lake Pontchartrain has extremely high levels of lead and sewage-related bacteria. The Coast Guard has reported at least five major oil leaks from damaged tanks and refineries, including 819,000 gallons spilled south of New Orleans. Then there's the 95-acre Superfund site near downtown New Orleans, a toxic former dump. Four years ago, it was covered with two feet of topsoil and protective sheeting. Now it's underwater and could be leaching chemicals.
Any one of these situations might be manageable, but taken together, the task leaves experts questioning where the resources will come from. The cost could run to tens of billions of dollars, especially if oil and chemicals seep deep into the ground. "We have cleaned up lots of other catastrophes and, quite candidly, this outstretches all of them combined," says William J. Geary, executive vice-president of Clean Harbors Inc (CLHB )., a leader in environmental cleanup, with workers already in the city. "This is orders of magnitude bigger than what any cleanup company would be familiar with."
The most immediate concern for health officials is the high levels of bacteria and lead in the rancid water covering much of New Orleans. The EPA has warned the water is so contaminated that people should not let it touch their skin, and five Louisiana evacuees have died of a cholera-like illness. Yet that water, essentially raw sewage, is being pumped into Lake Pontchartrain.
There's no chance of treating the water as it goes into the lake, as nearly all the waste treatment plants in the region were damaged by the flood. Bacteria normally dies off from exposure to sun and seawater after a week or so, but the lake may be so starved of oxygen that the natural cycle will be inhibited. Ward says it would help if oxygen were pumped back into the lake -- "nature does work if you let it" -- but right now New Orleans' main priority is getting the water out of the city.
Oil and toxic chemical spills present a far more intractable problem. Contaminated topsoil can be scooped up by vacuum-like machines, but those devices can't get at muck that has seeped into houses, sewer lines, or groundwater. There are novel technologies that can be applied. Last year, for example, Solucorp Industries Ltd. in West Nyack, N.Y., introduced a chemical compound that prevents heavy metals such as mercury and lead from leaching into the soil and makes them safe for disposal. Solucorp President Noel E. Spindler says the technology has not been tried on any project as large as the Katrina disaster site, but it could be deployed in certain areas. Such reagents will likely not be useful, however, in locations where a complex chemical cocktail exists.
The biggest problem will be disposing of all the waste. "This is going to be an absolutely enormous volume, and I doubt that much of it will be able to be recycled," says Edward J. Bouwer, an environmental engineering professor at Johns Hopkins University. There is no landfill in the U.S. large enough to accommodate a trashed city, and scientists say there is a limit to how much other nations would be willing to take. "The logistics, the cost, the volume," laments Ward. "It's just a massive, massive problem."
By Catherine Arnst in New York, with Janet Ginsburg in Chicago