When Nathan Imperiale and his wife chose to move to the Spring Valley neighborhood, they already knew what may be lurking underground.
Across the street, on American University's campus, a toxic clean-up is underway. In the 90's, crews found suspicious material near a stately home, remnants of a World War I munitions testing ground.
"It's a little disconcerting to know that this is going on across from where we live," Imperiale says. "But they've done a good job of making us feel comfortable and safe that nothing is going to happen to is."
That house has been demolished to make way for the excavation. But digging has come to a halt. Crews recently found a test tube with an unknown substance.
"Behind the retaining wall is where we encountered a 75 millimeter munitions debris item," says Brenda Barber, a Spring Valley project manager.
Barber says despite the find, residents shouldn't be worried. newly installed filters are designed to protect air quality.
"These will treat the chemical agent and they won't allow a release to the outside atmosphere," Barber says.
Where the brick home once sat, some of the walls and floors remain. Excavation is difficult.
The next phase of this project is to lift the basement floor, where underneath, experts believe hazardous material may still be buried.
Experts are investigating the test tube substance but Barber can't say with certainty when the project will resume.
If the material is hazardous, Barber and her team would likely reassess the dig strategy.