The U.S. Army Corps of Engineers has uncovered what could be a fourth major disposal area for World War I-era munitions and chemical weapons in the nation's capital. Project manager Dan Noble said on Thursday that digging was suspended April 8 as a precaution after workers pulled smoking glassware from a pit in the pricey Spring Valley neighborhood near American University.
Preliminary tests show the glassware was contaminated with the toxic chemical arsenic trichloride. Officials will review safety procedures before digging continues.
During World War I, the Army used the university as an experiment station to develop and test chemical weapons.
Previously, there were three known sites where weapons and chemicals were buried.