"It's a balancing act," Smith says, "to keep the high-risk areas cleaned up first and also be cognizant of the commanding officer's requirements for the land that he needs."
Critics of the military's environmental record speculate on less benign reasons for the gaps in knowledge. They point to the military's efforts to seek exemptions from environmental laws and say that cleaning up polluted bases is a low priority for an agency whose mission, before and after the Sept. 11 attacks, is national defense.
"The federal government has shoehorned these environmental cleanup responsibilities into a department that's not built to do those things," says Steven D. Taylor of the Military Toxics Project, a nonprofit group that aids neighborhoods near polluted military bases. As a result, "environmental surprises are pretty much ubiquitous at military sites. Many of the initial investigations have not been thorough, much less comprehensive."
In some cases, environmental compliance officials have faced retaliation for reporting problems, says a former Navy lieutenant, Daniel P. Meyer, who is general counsel for Public Employees for Environmental Responsibility, a whistleblower group in Washington. In 1998, the former environmental engineer at the U.S. Coast Guard Academy in New London, Conn., won more than $130,000 in a lawsuit alleging that the school fired him for reporting a toxic waste dump on school grounds to state and federal authorities.
In other cases, the military overlooked the obvious. The General Accounting Office, the investigative arm of Congress, recently studied 3,840 cases in which the Army Corps of Engineers concluded that former defense sites - many now parks, schools and homes - did not require cleanup. In 38 percent of those cases, the corps never looked for or ignored readily available maps, photos or records of likely pollution, the GAO found.
In 1992, for instance, the corps declared Puerto Rico's Camp O'Reilly free of pollution. But according to the GAO, the corps never reviewed archival records or even contacted the site's current owners, the University of Puerto Rico. Five years later, the university uncovered what the corps had missed: three underground storage tanks, a 12,000-square-foot dump and an area near a drinking water source tainted with oil byproducts. All were leftovers from the post's operations during World War II.
The cleanup could last as long as 10 years, says Robert C. Bridgers, who will manage it from the Army Corps' office in Jacksonville, Fla. But Bridgers says that nearly six years after the pollution was discovered, the corps' regional office in Atlanta has yet to approve his cleanup plan. What's more, he says, he has no money for the work.
"We'd like to do more quicker, and we can't because of funding," he says. "I've got live bazooka rounds in a suburban neighborhood in Brooksville, Florida, that I can't get to because I need $11 million, and I can't get it."
He is not sanguine about his chances in the current political climate. "With the war on terrorism now, environmental restoration may be less of a priority in Congress."
Experts say that another factor behind the tardy discovery of decades-old toxic sites was reforms to the federal Superfund program in the 1990s intended to speed cleanups. The changes came after criticism that many cleanups seemed mired in the investigative phase. But by allowing cleanups to begin even before crews had grasped the full scope of an environmental problem, EPA officials now say, the reforms may have inadvertently allowed some toxic waste to escape notice.
Stachiw, Aberdeen's environmental chief, said that 350 historic waste sites have been identified at the base, up from the 318 found in the first survey in the 1980s. "I'm not expecting to find another 300, but we could find 20 or 30 more, and they could be significant," he said.
At the Patuxent Research Refuge, a former Fort Meade firing range, hikers and anglers occasionally discover what Army cleanup workers missed. Today, the 60,000 visitors to the refuge each year must sign waivers at the gate promising not to sue if something explodes.
"It's for their protection and ours," Nell Baldacchino, a spokeswoman for the refuge, which the Army turned over to the U.S. Fish and Wildlife Service in 1991. "Even though they've done a sweep, we can never guarantee that, through erosion or whatever, stuff won't come to the surface."
Such former defense sites pose a far greater risk to the public than active bases, where access is often restricted.
But while the military has passed the halfway mark in cleaning up active bases, it is just one-tenth of the way toward a full cleanup of former defense sites, according to the Pentagon's financial figures.