Pueblo Chemical Depot seals five leaking mustard gas shells

U.S. Army officials have found and sealed five artillery shells from the Pueblo Chemical Depot in southern Colorado that had been leaking mustard agent.

The leaks were detected during an air test in September, according to the Denver Post.

Chuck Sprague, a spokesperson for the depot, told the Denver Post that crews installed a filter on the vent of the bunker and searched for the leak. These types of leaks can take between weeks and months to find as a result of each bunker containing thousands of shells.

The shells, which contained dried mustard agent, were found on January 6 and were then transferred to larger sealed containers last week, the Denver Post reports. In total, the depot contains 2,600 tons of mustard agents that are awaiting destruction under the international treaty.

The plant that is planned to neutralize all of the agent, the Pueblo Chemical Agent-Destruction Pilot Plant, is currently under construction, with neutralization work set to begin in 2015.

The depot, which is one of five Army installations in the United States that stockpiles chemical weapons, consists of approximately 23,000 acres and makes up seven percent of the nation's original chemical material stockpile. The organization in charge of the destruction of these chemical munitions is called the Assembled Chemical Weapons Alternatives program, which is an extension of the Department of Defense, according to the Army's website.