A limited area emergency was declared Wednesday when the vapor of dangerous mustard agent escaped into the atmosphere at Deseret Chemical Depot, in rural Tooele County.
Workers in the fenced-off "Area Ten" had removed a plug from a one-ton container of mustard agent when gas burbled out with such force that a protective seal was momentarily broken. Only a small amount of vapor escaped, and it quickly dissipated to undetectable levels. No injuries were reported.There was no shutdown of the Army's adjacent $600 million incinerator, which is destroying nerve agent munitions. The incident happened in "Area Ten," a series of igloos where chemical warfare agents are stored.
Chuck Sprague, spokesman for Deseret Chemical Depot, said that for the past year or two, base employees had been surveying the old munitions to check for corrosion. They had taken a one-ton container of mustard agent out of its igloo, strapped it to a large cradle device, shifted it upright, put a glove box over the valve and unscrewed the plug.
The container is shaped something like a propane tank. It had been lying on its side for about 50 years and a crust of sludge had formed inside. When the tank was tilted upright, sludge began sliding toward the bottom, Sprague said.
Meanwhile, workers had their hands inside a glove box, which is a heavy device that sits on top of the tank. It has windows and gloves built in. They were using the glove box to remove the three-quarter-inch diameter plug. They were also venting contaminated air from the tank into a container and filter system.
"As they started to decontaminate the plug, all of a sudden this muck started to come out of the hole" where the plug was removed, Sprague said. The material was forced out by the crust shifting in the tank. A bubble of gas must have been behind the muck, because after about a foot of it squeezed slowly out of the hole, a sudden burst of pressurized air filled the glove box.
The force was so great that the muck splattered the inside top of the glove box and the entire box momentarily lifted off the tank. The box weighs 250-300 pounds and is sealed with a rubber inner tube, but it all lifted off the tank.
"They got readings of three TWA in the breathing zone," he said. In other words, monitors detected mustard agent vapor levels of three Timed Worker Average. One TWA is the level to which a worker can be exposed 40 hours a week throughout his career without harm to heath. The workers were wearing protective gear and masks and apparently did not breathe in any of the vapor.
"The readings that we got were immediately around these three employees that were around this platform," Sprague added. People who responded to the emergency were required to wear masks.
However, air monitors 50 and 100 feet from the tank did not detect any vapors.
Col. Robert Coughlin, commander of Deseret Chemical Depot, declared an emergency because the vapor escaped into the open air. The three workers on the platform with the tank were checked by a doctor and showed no ill effects. Their suits were decontaminated.