For decades, the career diplomats and government lawyers who settled in the district's sedate, leafy neighborhood of Spring Valley heard rumors from area old-timers about what had gone on there during the waning days of World War I.
Their winding streets and sprawling stone homes had replaced a rolling field that once served as a test site, they were told, for poison gas. They viewed such talk simply as colorful ghost stories that made home seem a little more exotic and dangerous than it really was.
When the subject comes up these days, it is no longer idle titillation. The stories were all too true. Spring Valley has endured six years of the largest American excavation ever undertaken by the government to root out toxic munitions left over from the Great War.
At a cost of nearly $20 million, ordnance experts from the Army Corps of Engineers have swarmed into Spring Valley three times since 1993, digging deep into sections of private yards in search of glass canisters and metal drums laden with the remains of mustard gas, lewisite and other poisonous agents.
Little of the feared buried cache has been found. But poison traces have been detected on enough material exhumed from several pits to lead the government to repeatedly extend its digging.
The corps' research through military records found that the area had housed a series of trenches and fields used by the American University Experiment Station to test poison munitions for the government in 1917 and 1918. Animals were exposed to mustard gas and other skin-blistering agents. Shells were burst in confined spaces and out in the open.
But there were few old maps or logs to pinpoint what was buried 80 years ago and where it was left. Without a trail, the ordnance experts can only keep shoveling until they, the neighbors and district health officials are all satisfied that they have dug enough.
"I think everyone wishes this would be over by now," said Priscilla Holmes, a lawyer and three-decade Spring Valley homeowner who lives a block from a 10-foot-deep pit covered by a massive tent to protect against poison leakage.
There had been talk of bringing the hunt to an end this summer. Now the agency hopes to pack up by October but concedes December is more likely.
"We've found a lot more than we've anticipated," said Maj. Brian Plaisted, the Army Corps official who oversees the project. Since March alone, Plaisted said, searchers have turned up 300 buried cylinders, containers and drums. Most appear to be scrap, but about 50 items suspected of once carrying poison gas will have to be painstakingly analyzed. And the pit itself, already twice as wide as originally proposed, may grow even larger before they are done. "We know we have to go wider, but we still don't know by how much," Plaisted said.
A contractor digging a utility line triggered the project in 1993 by unearthing an artillery round. The corps thought it had done as much as it could do after a two-year dig retrieved 43 suspected chemical shells and containers.
But district health officials, convinced there was more toxic refuse scattered in other buried trenches and test sites, pored over old photographs and interviewed elderly residents. Their investigation convinced the corps that other sites had to be excavated as well.
"Before they could walk away, they had to exercise some due diligence," said Theodore J. Gordon, a district deputy health director.
The corps has gotten good marks from most neighbors for keeping them abreast of the new digging sites and taking steps to protect them from the shards being unearthed. But residents' patience has been tested. Those living closest to the dig have endured several evacuations, the most recent in June. "There was some anxiety at the start, but after six years we're pretty used to it," said William Harrop, president of the Spring Valley/Wesley Heights Citizens Assn.
Still, some neighbors worry about excessive levels of arsenic detected in soil samples--a concern Gordon and city officials share. The corps will not be finished, Gordon said, until "they determine if there are any dangerous [underground] pathways that might impact on people's health." Without digging up the entire neighborhood, Gordon cautioned, "there are no absolute assurances we'll get everything."
That leaves Spring Valley's residents with little else to do but put their faith in the diggers and adopt whatever health precautions officials prescribe to avoid any contact with toxic substances.
When diggers arrived in 1993, Harrop said, the danger seemed remote. The idea that their exclusive neighborhood was built over the remains of a storehouse of poison gas seemed "preposterous."
But now, he said, "I think we're beginning to realize how much history there is around us. When even a quiet place like ours can have a background like this, it makes you wonder what you could dig up just about anywhere."