MALMSTROM AIR FORCE BASE, Mont. -- A roaring boom echoed throughout the canyon of Yellowstone National Park on June 12, 2023, when the Explosive Ordnance Disposal Team from the 341st Civil Engineer Squadron detonated an unexploded avalanche round.
It was 11:30 a.m. on June 11, 2023 when command post received the notification from Yellowstone park rangers, that an unexploded 105mm avalanche control round made its way down a mountainside to within 10 feet of the main route of travel in the park.
With the park beginning its peak season for visitors, the main concern for the EOD team and park rangers was to quickly and safely dispose of the explosive without increasing threat to any visitors.
“Upon notification of the item being found, we talked through actions such as blocking off the road to traffic,” said Master Sgt. Tristan Crandall, 341st CES EOD operations and training section chief. “Following the receipt of more pictures from the rangers, further discussion yielded the course of action to not close the road but to place a ranger in view of the item and cordon it off to prevent visitors from getting close or handling the item.”
During the winter season, national parks use explosives to trigger avalanches in order to prevent them from occurring naturally and potentially harming people or damaging infrastructure. To determine when this measure is needed, the park rangers will use a combination of weather data, snowpack analysis and on-the-ground observations to determine when to trigger an avalanche. They also consider the potential risks to people in the area and work to schedule detonations at times when the risks are minimized.
The unexploded round reported by the park rangers had a fuse sheared off on impact which caused the explosive to malfunction and trigger incorrectly. In the 50-year history of the avalanche control program at Yellowstone, only 12 munitions have reportedly failed to work.
Once the EOD team arrived at the location of the item, they and the Yellowstone Park rangers worked together and talked through a plan of action for potential detonation locations, general safety and explosives briefings.
“Our primary concern during the operation was keeping the public safe and detonating the item in a manner as to not cause additional hazard, such as fragmentation,” said Crandall.
The team decided the safest plan of action was to destroy the item in the trench between the shoulder of the road and the snowbank, placing sandbags on top of the device to mitigate possible fragmentation from becoming a hazard to the personnel.
EOD urges everyone to be aware of their surroundings out in nature and if you find an item that appears to be a military round or explosive, leave it alone and call 911.