This is an archived article that was published on sltrib.com in 2015, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.

Researchers this week plan to release a concentration of chlorine gas on the U.S. Army's Dugway Proving Ground.

The test is being named Jack Rabbit II. Scientists are seeking to determine what would happen if a rail car or other large receptacle were to emit pressurized, poisonous gas in an urban setting.

The tests are in cooperation with the U.S. Department of Homeland Security, and planning documents suggest it and the Army intend to place cars and structures in the test zone to see whether the chlorine penetrates them.

According to the Utah Division of Air Quality documents released last year, Jack Rabbit II calls for Dugway to release up to 10 tons of chlorine. The amount could increase to 90 tons of chlorine per test in 2016 if Dugway can demonstrate that only minimal amounts of chlorine escaped its boundaries in previous tests.

The amount of chlorine allowed to escape Dugway boundaries must be two magnitudes less than what is typically harmful to humans. Any DAQ permit would specify the weather conditions under which the chlorine could be deployed, including wind speeds between 2 and 6 meters per second.

The testing will be conducted in locations with little vegetation or trees that would attract birds, and Dugway plans to use noisemakers and other methods to remove any animals from the area.

An earlier version of Jack Rabbit was conducted at Dugway in April and May 2010. In those tests, scientists wanted to learn how clouds of chlorine and anhydrous ammonia move.

Dugway dug a hole 2.2 meters deep and 27 yards in radius, moved personnel back at least 1.5 miles and remotely deployed the gases in the hole.

The proving ground, which sits in a remote desert area 85 miles southwest of Salt Lake City, opened during World War II to test chemical and biological weapons and defenses against them.

It made headlines recently for mistakenly shipping live anthrax to labs across the United States and in other countries.

The most famous earlier incident involving Dugway happened in mid-March 1968. As Dugway was in the midst of open-air testing of the nerve gas VX, thousands of Utah sheep in Tooele County's Skull Valley began dying.

A 1970 report by researchers at the Army's Edgewood Arsenal in Maryland said there was "incontrovertible" evidence that a nerve gas killed the sheep, but the Army never has acknowledged that it, or the Dugway testing, was responsible.

Twitter: @natecarlisle