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Firefighters deal with a number of incidents they describe as high-risk, low-frequency events. Trench rescue is one of them.
In early April, firefighters gathered at the Minot Fire Department’s training rounds to practice trench rescue. It marked the first official usage of the department’s new concrete trench training site.
“One of the challenges we’ve had with trench rescue training in previous years is that we’d have to bring someone with a backhoe in to dig a hole for us,” Battalion Chief Glen Hardy said. “Having an open trench presents all kinds of potential problems for us.”
The longer the edges of an open trench are exposed to air, the more the dirt on the edges dries out and becomes susceptible to collapsing. Plus, Hardy said, the ever-changing schedule of the Fire Department means a trench could sit open for days before all crews have a chance to complete training.
“Some of the battalions might not get to the training for four or five days. Just because we have training scheduled doesn’t mean we can stop answering calls,” he said. “So an open trench might sit there for days in the sun, or we might get a heavy rain. All of that presents potential problems for training.”
The new concrete trench training site eliminates those concerns. Now, firefighters can train under safe conditions, without worrying about experiencing an actual trench collapse during training.
“This allows us to have a clean, stable area to practice our trench rescue training,” Hardy said. “It’s safe for us so we can focus on our training.”
Trench collapse rescue is just one of several high-risk, low-frequency calls the department could respond to at any time. They don’t happen often, but when those calls come in, the responding firefighters must have proper training.
“We try to conduct this training at least once a year, even if it’s something we rarely use,” Hardy said. “When that type of call comes in, we know we’ve trained for it.”
On this April day, some 20 or so firefighters gathered around the concrete training site to discuss how to approach a potential collapse, then practiced using a system of wooden panels and pneumatic struts to shore up the walls of the trench.
“When commercial companies dig for water breaks or other underground work, they’re always supposed to use trench boxes to brace the walls against collapsing,” Hardy said. “But if it’s a private person digging, or if a company doesn’t follow the rules, you can have a trench cave-in, and that’s a dangerous situation.”
In a real trench collapse emergency, there would be only a few firefighters near the trench and crews would try to keep any equipment at least 300 feet from the trench to avoid ground vibrations making the situation worse.
“The fewer people around the trench the better,” Hardy said. “Even seemingly small vibrations can make the situation worse, so we have to be aware of that while we’re working to shore up the trench and rescue any potential victims.”
They always have to think about their own safety, too.
“I don’t think most people think about how much dirt can weigh. It’s extremely heavy,” Hardy said. “A collapsing trench wall can break your legs very easily if you’re down in the trench. Or worse. If you get caught in a trench collapse, you might be lucky if you only break a leg because you can get buried very quickly. These are dangerous situations.”