U.S. ARMY DUGWAY PROVING GROUND, Utah -- Years of meticulous planning, public meetings, engineering, environmental studies and other labors recently culminated in tests lasting minutes, to improve defenses against chlorine gas.

Funded in part by various federal agencies, the Jack Rabbit II test studied how gaseous chlorine might flow among urban structures and vehicles in an attack or industrial accident. Over 10 days, two 5-ton and three 10-ton liquid chlorine releases occurred at a remote salt flat on U.S. Army Dugway Proving Ground (DPG) Utah, 40 miles from any residence. It went from liquid to gas in seconds, (chlorine boils at -27 Fahrenheit). Its greenish yellow cloud moved across the bare earth and around shipping containers arranged to replicate an urban array of buildings.

"The test was a success. We did five trials. We collected data that we're in the process of analyzing," said Damon Nicholson, Dugway Proving Ground (DPG) test officer for Jack Rabbit II.

The need to learn how chlorine gas might move around city buildings, or a neighborhood, is crucial as chlorine is noted as one of the world's most common hazardous industrial chemicals. Chlorine is used in water treatment, plastics, laundry bleach, paint and pharmaceuticals. Today, in America alone, 13 million tons are produced annually. Most are transported by rail, truck and ship for industrial uses. The Centers for Disease Control (CDC) noted last April that chlorine is in the top five chemical incidents associated with injuries because of its hazardous properties.

For the Jack Rabbit II tests, a 10-ton storage tank was specially designed by the agencies conducting the test. The reusable tank was designed with four flanges at different locations to allow for different scenarios, and remotely triggered explosive bolts were used to detach the flange and release the chlorine. The gas flowed among vehicles and shipping containers that replicated traffic, buildings and houses.

Utah Valley University (UVU) contributed two fire engines, one rangeland fire truck, an ambulance and a handful of cars, to learn how much protection they provide. An instrumented mannequin in firefighter turnouts and self-contained breathing apparatus was atop the ambulance, to learn if exposure was reduced by climbing above the heavier-than-air gas as it followed the ground. Instruments in and around the containers and vehicles measured the gas' intrusion, flow or concentration.

Data are currently being analyzed to determine whether those in danger should shelter in place, seek a higher level, or attempt to flee. The results will be analyzed for months to come, Nicholson said.

"It's never been tested at these (5 and 10-ton) scales before,' said Shannon Fox, project manager lead scientist for the Department of Homeland Security's Science & Technology Chemical Security Analysis Center. "Now we have the data to more accurately make hazard prediction models, and help emergency responders and planners prepare for an event like this."

The Utah Department of Air Quality established meteorological limits for each release. Testers required narrow wind and direction parameters for safety and good data. Chlorine detectors were placed miles from the remote test site. "Everything was done safely," Nicholson said. "We didn't see any chlorine off post; it was all contained within Department of Defense property."

With DPG's 800,000 acres, and the Air Force's adjoining Utah Test & Training Range of 1.7 million acres, there was ample space for the chlorine to dissipate. Next summer, Jack Rabbit II plans to continue with up to 16 tons of additional releases of chlorine", Nicholson said.
Chlorine does not present a long-term environmental or health hazard. As a highly-reactive chemical, it rapidly reacts away to become non-toxic products, such as chloride, which is found in table salt, said Fox. In 2007 and 2008, Iraqi insurgents attached chlorine canisters to improvised explosive devices in attempts to bolster their lethality. "It can be used here intentionally, and that's a concern because we have millions of tons being transported every year on 90-ton railcars and 20-ton tanker trucks," Fox said. 'They're being transported through urban areas every day."

Richard Collins, environmental health scientist for the Centers for Disease Control, deals with the public health effects of toxic chemicals in environmental health emergencies. He had high praise for DPG capabilities and its personnel. "I thought this was a well-thought-out experiment," he said. "I can't say enough that they have done their homework up front to consider all factors involved in the experiment, to include safety considerations for the personnel involved."