A mustard leaker operation in Pueblo was shut down Tuesday afternoon.
Low-level readings of mustard agent vapor at the Pueblo Chemical Depot were detected on September 21, 2010 during scheduled igloo monitoring operations. The trace readings were inside a storage structure containing 105 mm projectiles.
Chemical crews began an operation to isolate individual pallets of the stored projectiles to locate the munitions. Five munitions on a pallet with dried, crusted mustard agent was located on January 6. The five munitions have been transferred.
An air filtration unit was installed in the storage structure shortly after the discovery of the mustard agent vapors, and had been in continuous operation until Tuesday, when the leaker operation concluded.