People in the Salt Lake valley might hear and feel reverberations from explosions from early April through late October, but they shouldn’t be alarmed — those loud booms have a purpose.
It’s a windy late morning on the observation site at the Tooele Army Depot. A crew member is covered from knees to toes in white, dusty dirt. Several staff members look out across the flat desert landscape toward hills far off in the distance. They’re waiting for the first of 10 detonations, each separated by a minute.
Suddenly, a dark cloud of dust rises from the ground. There’s a shockwave, and about five seconds later, a loud boom.
The 10 detonations only took about 15 minutes.
These explosions aren’t just for show. The depot is a U.S. Army Joint Munitions Command that focuses on demilitarization by open detonation. It’s one of 10 such sites in the country.
Col. Luke Clover, commander of the depot, said the primary mission is to receive, maintain, store and distribute munitions.
“The importance of our demilitarization mission is making sure that the uniformed service members and all of the services of our armed services have the most capable and dependable munitions should contingencies arise where they have to utilize those munitions,” Clover said. “It also allows us to free up storage from those munitions that are no longer in use or deemed unsafe to hold and build the nation's wartime stockpile of munitions for future contingencies.”
Nearby municipalities are alerted of planned detonations by emailing local officials and residents, and by posts on social media.
The process of detonation has several steps.
First, munitions are placed in a deep pit. Then, a crew prepares what’s about to be blown up with a continuous loop of detonating cord. Once that is set, the crew buries it with the surrounding white dirt. After the blasting caps are placed and tied to the firing lines, a lock box is opened from a shack, and a shunting plug is plugged into the firing panel, which controls what is fired.
Dan Wall, the branch chief of conventional ammo maintenance and demilitarization, said Tooele is the first depot to run this particular system.
“It really gives our employees that confirmation of safety while we're on the range, and it also gives us that confirmation of safety that we can control each detonation individually and meet the end state of our mission,” Wall said.
Erin Trinchitella, the director of industrial operations, said the particular makeup of the soil makes this spot in Tooele County a good place to detonate.
“So if there is an accidental explosion, the soil here, both the north and the south that we're on, helps absorb that,” she said.
Trinchitella said they used to detonate on the north part of the depot, but Utah’s speedy growth has complicated that. They moved operations south because of nearby cities.
“It's beneficial to everyone that we do it here,” she said.
After the last round explodes at the demonstration, dust blows toward the Salt Lake valley. But Lonnie Brown, who serves as the division chief of environmental management, said that even though some of the dust contributes to PM10 particles in the air, most of it will dissipate before it reaches the valley.
Brown said the depot works closely with the state to assess environmental risk and health hazards. That goes for people and animals. It’s common to spot local wildlife nearby, like antelope, even after 10 detonations.
Still, the depot conducts ecological studies to remain within requirements set forth by the state and the Environmental Protection Agency. The depot also works with the EPA on groundwater regulations and has installed wells to track any negative impacts.
“We test it frequently,” Brown said. “We find that there's no significant impact on these wells.”
Commander Clover said the depot wants to share with the community what’s going on out here, so that people remember why they might be hearing explosions and booms through the summer.
“We're not trying to hide anything,” he said.