The Army's incinerator near Stockton, in Tooele County, is set to resume burning chemical warfare agent later this month in the plant's last campaign.

The furnaces at the Tooele Agent Disposal Facility have been shut down for more than a year.

"We finished processing VX (nerve) agent early in June 2005," said Alaine Southworth, spokeswoman for Deseret Chemical Depot. The depot is where the incinerator is located and where lethal chemical warfare agent remains stockpiled in protective igloos until it can be destroyed by burning.

Among the tasks at the incinerator has been decontaminating the facility so that workers can use lower-level protective clothing.

Southworth's best guess for the restart is for the week after Aug. 17, but the timetable is not yet definite.

Since incineration halted, workers have been changing over from destroying VX to getting rid of the final remaining material at the depot: blister chemicals called mustard agent. "We've had to change some of the machinery over to be better prepared to handle the mustard," she said.

Mustard agent is an oily liquid that causes severe blistering. It can volatilize, forming a gas that damages or destroys the lungs and burns the skin or eyes.

Used by German and British military units in World War I, mustard was the cause of the vast majority of chemical-weapons injuries in that war, according to the Army's Medical Research Institute of Chemical Defense.

Of 36,765 U.S. soldiers who were wounded by single-type chemical weapons in that war, 75 percent suffered injuries from mustard, the institute said. More than 2 percent died.

Iraq is known to have used mustard agent against Iran during the Iran-Iraq War in the 1980s.

The United States has stored stockpiles of mustard agent.

The depot's official schedule calls for the last of the mustard agent to be destroyed by 2016, but "our goal is 2012," Southworth said.

More than 6,000 tons of mustard agent remain at the site, most of it in bulk containers, each holding about one ton. But munitions like 155 mm projectiles and 4.2-inch mortar cartridges remain. Altogether, more than 124,000 items are left to be destroyed.

The plant is also sampling containers and sorting them by level of mercury contamination. "We know that some of our containers of mustard have elevated levels of mercury," Southworth said.

For the first two or three years, the incinerator will process containers "with little or no mercury in them," she said. Those with elevated levels will be stored until a method is developed to capture the contaminant.

Because mercury is an element, it cannot be destroyed by incineration. It turns to vapor if heated. The plant intends to capture mercury, Southworth said, "so that we'll stay within our permit."

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