DENVER — The U.S. Army could begin destroying the nation's largest remaining stockpile of chemical weapons as early as Wednesday.
The Defense Department has given the go-ahead to start eliminating 780,000 shells containing 2,600 tons of mustard agent at the Army's Pueblo Chemical Depot in southern Colorado.
Work could begin Wednesday if the weather is favorable for moving the material from a storage bunker to an airtight structure where the first destruction will take place, depot spokesman Thomas Schultz said. Managers don't want to expose crews or the containers to storms, Schultz said.
Wednesday's forecast called for a slight chance of showers in the afternoon.
Mustard agent can maim or kill by damaging skin, the eyes and airways. It's being destroyed under a 1997 international treaty banning all chemical weapons. It will take four years to destroy the Pueblo stockpile.
Another 523 tons of mustard and deadly nerve agents are stored at Blue Grass Army Depot in Kentucky. Blue Grass isn't expected to start destroying its weapons until 2016 or 2017, finishing in 2023
The destruction process is safe, officials said.
Most of Pueblo's stockpile will be dismantled and neutralized in a highly automated $4.5 billion plant built at the depot.
About 1,400 damaged shells and a dozen metal bottles of mustard agent are considered unsuitable for that plant. So they'll be torn open with explosives inside a sealed chamber, and the mustard will be chemically neutralized.
The metal bottles contain mustard that was extracted from the shells for testing. They'll be the first to be destroyed, followed by the damaged shells, Schultz said.
The explosion chamber is ready to start operating, officials said, but the automated plant isn't expected to begin work until December or January. Design and construction have taken years, and final testing and training are underway.
Mustard agent is a thick liquid, not a gas as commonly believed. It has no color and almost no odor, but it got its name because impurities made early versions smell like mustard.
The U.S. acquired 30,600 tons of mustard and nerve agents, but it never used them in war. Nearly 90 percent of its original stockpile has already been destroyed.