Umatilla Depot to destroy mustard gas

Workers at the Umatilla Chemical Depot have begun the process to incinerate the last of the chemical weapons stored there.

Workers began delivering bulk containers filed with mustard blister agent to the depot's disposal facility Thursday morning, after the state of Oregon gave final authorization Wednesday evening to incinerate the agent.

"Our experienced crews are dedicated to safe and secure munitions movement and delivery to the disposal plant," Lt. Col. Bob Stein, depot commander, said in a statement. "Deliveries have gone very well during the 12 previous munitions campaigns, but risk remains until the last ton container is gone."

The work is expected to take one to two years, which should easily meet an April 2012 international treaty deadline.

The depot was established in the early 1940s, and chemical weapons have been stored there since 1962. Workers finished destroying military nerve gas last November.

Work has been under way since then to prepare the processing plant for the mustard incineration. That included bolstering systems to prevent the release of mercury into the air, training plant workers and retrofitting the plant to process one-ton containers.

The mustard agent is held as a liquid in 2,635 one-ton containers used for storage and shipment. Although there were far more containers of deadly VX and sarin nerve agent stored at the depot, the mustard agent made up more than half of the depot's stockpile by weight.

The mustard agent at the depot dates to World War II. While toxic, it is less lethal than the nerve agents that were destroyed there earlier.The mustard agent takes up to 24 hours to cause chemical burns or blisters to tissue it touches, including the eyes and lungs.

At the disposal facility, the containers will be drained and the mustard destroyed in an incinerator at 2,700 degrees. The containers will be sent to a furnace to be decontaminated for up to 2 1/2 hours at 1,600 degrees.

When the chemical munitions destruction is complete, toxic areas in the disposal plant will be thoroughly cleaned and disassembled according to environmental permits and the depot will be closed.