A leak of deadly mustard agent prompted Deseret Chemical Depot to declare a "limited area emergency" on Monday.
Jon Pettebone, spokesman for the depot, said so little vapor got into the outside air that the incident posed no danger to nearby communities or the environment.
The depot, located near Stockton, Tooele County, is where nerve and blister agent munitions are stored and where the Army's $1 billion incinerator will destroy them. (The incinerator has been shut down since it released a tiny amount of GB nerve gas the night of May 8-9, but it is expected to resume work within a few weeks.)
In the latest incident, liquid mustard agent leaked from seven 155-mm projectiles stored inside an earthen bunker. The liquid gave off vapors.
The bunker is monitored daily, according to Pettebone. On Monday, when its door was opened, agent vapors were detected outside the bunker. The depot declared a limited area emergency.
"It has happened before," he told the Deseret News on Tuesday. Mustard agent vapor escaped the bunker, but so little was involved that it diffused harmlessly before it could drift out of the storage area, Pettebone added.
A team of workers wearing protective gear entered the bunker and decontaminated agent discovered on the floor, he said. About a pint had leaked into the cement.
The team sampled weapons until they identified the leaking projectiles. The projectiles were placed in overpacks so they would not cause any harm while awaiting destruction in the incinerator.