SALT LAKE CITY, Utah (AP) -- The Army has begun draining and incinerating thousands of containers of mustard gas held in storage at a facility in the Utah desert.

The project at the Deseret Chemical Depot, begun Friday, will last six to 10 years. It involves burning about 6,200 tons of liquid blister agent and is complicated by the presence of an estimated 800 pounds of toxic mercury.

At one time, the depot housed more chemical weapons than any other U.S. storage site. To comply with the international Chemical Weapons Convention, the U.S. government began weapons destruction there in 1996.

The destruction of the mustard gas is the final phase in the project.

Mustard gas, which is a liquid at room temperature, causes severe blisters, internal and external bleeding, and strips mucous membranes from airways.

Workers will first drain and incinerate the 1-ton mustard gas containers, depot spokeswoman Alaine Southworth said. They will also design and install filters to scrub mercury from the exhaust, she said.

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