A year ago, the U.S. Army Corps of Engineers thought chances of finding any more chemical weapons in the front yard of a home in the nation's capital were slim. So they removed an airtight protective structure from the World War I munitions cleanup site. Then, they uncovered a small arsenal.
The Corps discovered an open flask containing traces of the chemical agent mustard, another blistering agent called lewisite and munition shells with more digging near a one-time Army chemical warfare station at American University.
More recently, protective structures were rebuilt and digging continued. Workers found a larger jar with mustard, glassware that was smoking and fuming, scrap munitions and a shell containing a tear gas agent.
The Army Corps has removed more than 500 pounds of glassware and scrap metal and nearly 750 barrels of soil, some of it contaminated with chemical agents, said spokeswoman Joyce Conant.
"It's a much larger disposal area than we predicted," project manager Dan Noble told The Associated Press on Thursday. "The nature of debris is so different, perhaps it's a different disposal area."
It's too soon to know, though, whether the Army Corps has uncovered a fourth major disposal area in the pricey Spring Valley neighborhood near American University, Nobel said.
During World War I, the Army used the university as an experiment station to develop and test chemical weapons. Some munitions were fired into a nearby wooded area during testing. When the Army station closed, the leftover munitions and chemicals were buried behind the school in what was then rural farmland.
The pits were discovered in 1993 as homes were built. This is the fourth major excavation since.
All the new discoveries have area residents on edge the Army Corps has underestimated the scope of contamination. Neighbors are thinking of their drinking water, property values and where the next munition might turn up.
"I think a lot of people believe that they need to re-examine their assumptions," said Nan Wells, a neighborhood commissioner.
Wells said there should be an independent review of the project and the Army Corps should increase its ground water testing in the area to make sure buried chemicals don't reach a nearby reservoir serving Washington. Ground water monitoring stations have been set up in recent years.
The home where the latest munitions were uncovered is federal property. Next door is the university president's home, and the South Korean ambassador lives on the other side.
In late March, the Army Corps uncovered the smoking chemical arsenic trichloride for the first time in the cleanup project. It can be used to develop the blistering agent lewisite, Noble said. Digging was halted shortly after while officials review their safety procedures.
American University spokeswoman Camille Lepre said there were no plans to move or cancel any campus events scheduled at the president's house.
On Friday, the Army Corps began destroying the first of about 25 munitions at a holding facility built in the area, a process that will take several weeks. Officials stress the explosive destruction system, as it's called, has a perfect safety record.
Still, some residents worry that something could go wrong.
"They've created a hazardous waste site in the neighborhood," Wells said.
Col. David Anderson, commander of the Army Corps' Baltimore district, said residents' safety is their top priority.
The Army Corps has left the neighborhood in the past, thinking the cleanup was finished, and the agency now faces federal budget cuts. But Washington's delegate in Congress, Eleanor Holmes Norton, said she has been assured funding will be maintained until all munitions are removed.