December 2009: Feature Story

The Essential Inequity of Trench Mishaps
A Veteran Firefighter Talks About Trench-rescue Techniques, the Insidious Nature of Trench Accidents and the Basic Unfairness of It All
By Walt Moore

Steve White’s presentation will make you promise yourself, that if ever you must work within an excavation, you will refuse to do so unless protected by shoring or shielding. One photo in the presentation looks into a partially collapsed, 11-ft deep trench, where a worker has been buried to his waist. Only the victim’s hand is visible, the rest of his body obscured by an immense chunk of clay, weighing an estimated 300 lbs, which has been stopped inches short of crushing his torso by — of all things — a shovel that he had rested (providentially?) at just the right angle against the trench wall.

White is a very personable man, but let’s all hope that we never have to meet him professionally. In addition to being Battalion Chief for the Town of Fishers, Ind., fire department, he is also the team leader of the Hamilton County Rescue Task Force, a technical-rescue group that specializes in safely extricating humans trapped in dangerous, difficult-to-access places, such as wrecked vehicles, collapsed structures and confined spaces — the latter ranging from grain elevators to caved-in trenches. The presentation noted above details a recent Task Force rescue and is used in White’s training sessions, which also include in-the-trench practice.

During late August in Indianapolis, White and several other technical-rescue experts — Lieutenants Todd Muth and Eric Mohr with the Fishers’ fire department, and Russ Shoaf and Gerald George, Deputy Chief and Fire Chief for Pike Township, respectively — conducted a two-day trench-rescue training session for a group of central Indiana firefighters. The trainees are members of Indiana’s Task Force One, a disaster-response group under the authority of the Federal Emergency Management Agency (FEMA).

“These men will receive 300 hours of disaster-response training, including handling situations involving weapons of mass destruction,” said White. “But just as important, they’ll also take the skills they learn back to their respective fire departments.”

The Challenge of Rescue

Truth be told, the site of the training — a large open field owned by Caterpillar dealer MacAllister Equipment Co. — had somewhat of a threatening atmosphere, with the presence of emergency vehicles, 20-plus blue-helmeted firefighters and all manner of rescue apparatus. Among the objectives for the training session, explained White, were learning techniques for shoring intersecting trenches and for safely extricating trapped workers.

In this instance, the realistic-looking dummy “victim” was pinned at the bottom of a trench under an excavator bucket that had (in the training situation) disconnected from the machine’s coupler. The bucket had come to rest just short of the prone victim and was supported precariously by the narrowed walls at the trench bottom.

In defense of the on-site Caterpillar excavator that MacAllister had loaned the firefighters for ongoing training, the dealer’s Underground Specialist, Taylor Clark, who assists in arranging the training sessions, says that the Cat Center-Lock coupler actually is designed to prevent such mishaps by combining an over-center mechanical lock with two hydraulic locks to ensure positive work-tool retention.

“The challenge when making a safe trench rescue is to make sure our shoring meets OSHA 1926 standards,” says White. “We’re not above the law, and the soil is just as dangerous to rescuers as to contractors. The difference, of course, is that the contractor can make a fairly square excavation and install shoring to fit, but most of the time we have to make our shoring conform to a trench that has collapsed.”

The discipline to follow safe procedures is extremely important for rescuers, says White, because the first impulse is to get to the victim and render assistance. If the victim’s hands are free, he says, rescuers might lower an oxygen mask, but they must be careful to do nothing that might cause a secondary collapse.

Secondary Collapse and the “Silent Killer”

Among initial procedures at a trench rescue is to identify, locate and control utilities such as dangling electrical wires and exposed gas lines and to place ground pads (sheets of plywood or planking) around the perimeter of the trench to distribute weight.

Next is the placement of vertical shoring panels, which are held in place by pneumatic shoring cylinders that are mechanically locked when extended between the panels. Pressure in the cylinders can vary between 35 and 300 psi, depending on the instability of the trench walls.

“We try to get the first set of panels as close to the victim as possible because we want to establish a safe entry for a paramedic,” explains White. “In a trench accident, you’re always fighting a secondary collapse and the silent killer — a crushing-type injury — which can release toxins in the victim’s body. There are medications that help mitigate the effect of these injuries, and we want to provide those as soon as possible, along with medication to manage pain.”

White explains that crushing injuries can jeopardize the victim’s limbs — and life — by exerting a damaging pressure from either the outside (crush syndrome) or from the inside (compartment syndrome). In the former, the pressure of material in a collapsed trench damages muscle cells and compresses large vessels, which results in loss of blood supply (ischemia) to the muscle. Normally, muscle cells can withstand four hours without blood flow before dying, but ischemic cells can begin to produce and leak a number of deadly toxins in as little as half an hour.

Compartment syndrome has similar consequences, but the pressure in this instance results from an injured muscle that tries to swell within the restricted “compartment” formed by the tough membrane (fascia) that surrounds it. This internal pressure collapses blood vessels and muscle cells — again resulting in ischemia and the release of toxins, which may be produced for as long as 60 hours after extrication. Workers who have been trapped for a short time in a shallow trench that posed no threat of further collapse may think they have sustained no real injuries upon extrication, only later to fall victim of crush or compartment syndrome toxins.

The Rescue Continues

When the Hamilton County technical-rescue team responds, it does so with a crew of 30 and plenty of backup equipment. But having all of the captive equipment that might possibly be required on a technical rescue is virtually impossible, says White, both from a funding and logistics standpoint. For that reason, he says, the team has established working relationships with public-works departments in local municipalities and with private-sector contractors to supply equipment if needed.

When the Hamilton County Rescue Task Force recently arrived on a trench-collapse scene, rescuers encountered a 300-lb chunk of clay that was being kept from crushing the victim by a shovel placed against the trench wall.

“For example, we have our own vacuum-extraction system ready to go, but we need the municipality’s vacuum truck to hook up with,” says White. “We also have our own air-knife system, but in some instances, we might need to call on the municipality’s street department or a local contractor for a large air compressor. Before air-knives and vacuum trucks, we used army shovels and a bucket brigade to remove earth from around the victim — took forever.”

Back at the Indianapolis training site, the victim has been patiently waiting to be rescued while the crew practiced the complex procedure of safely shoring intersecting trenches. That accomplished, the trainees began the rescue by installing shoring panels and cylinders, placing air bags behind certain panels to fill voids, thus keeping the panels vertical.
The crew then fashioned a stout beam (made of 2-in. planking) across the trench, allowing a rescuer to kneel safely above the trench and work a ratcheting-chain puller that lifted the bucket with a fabric sling. The puller, in turn, was attached to the excavator’s bucket cylinder. The victim was removed, a bit dirty, but completely safe and ready to be trapped another day.

Back to the Providential Shovel

All this time, the shovel that the real trench-collapse victim placed at the beginning of this story has been holding up the mass of earth that threatened to crush him. And the shovel did hold, giving rescuers enough time to secure the trench, remove the threatening earth and bring up the victim. But the process required four hours of tense work, two of the city’s vacuum trucks, most of its police force and the shut down of an entire square-block of electric power.

And, yes, as White sums up the incident, “the worker spent another Christmas with his family.”

White is understandably sensitive to unsafe practices involving excavations, and when he’s on duty and out in his official “Fire-SUV” (a Chevy Suburban), he admits to stopping at work sites where he sees particularly dangerous situations and having a chat with the contractor.

“I have no authority in those situations, but when I get out of an official vehicle, in uniform, with a badge and wearing a fire helmet, there’s a certain intimidation factor. If the contractor is particularly rude — well, there’s always the city’s development department that control permits. If a negligent contractor asks his employees to work in an unprotected trench and things go wrong, then I have to place the lives of my guys on the line. That’s an inequity I don’t like.”

Walt Moore is a Freelance Editor based in Roselle, Ill.