Soil Collapse Conditions Illegal, Preventable

In the previous post, Don't Dig Too Deep, I wrote of the alarming extent of death and injury related to soil collapse. Historically there have been 100-300 deaths a year in the US due to soil collapse. One would hope that the current level is far lower, since these deaths are preventable, and the conditions that cause them are largely illegal to send workers into. News coverage of trench collapse is often cavalier when it reports survival, celebrating a can-do attitude and sidestepping a duty to inform. News readers deserve to be told how extensive the problem is, industry standards, or how they can take simple steps to avoid future injury to themselves and their loved ones.

Injuries that occur in the workplace deserve to be covered in the news from the point of view of compliance and employer ethics. All news coverage I have ever seen on these tragic work-related events leave off the preventable and illegal aspects of the event. The story in Georgia that prompted my post was no different.

Jordan Barab has been posting on this issue with the news media: trench collapse should not be treated this lightly; most workers do not come out alive.

Soil collapse is quiet and quick. Soil goes from supported to free fall in an instant. A collapse event initiates with little or no warning to a trench occupant. It is loudest at the end of the collapse event, yet seldom heard beyond the immediate area of the trench. Unless it is witnessed directly, or the victim can make themselves heard, a rising cloud of dust is the only evidence available to alert coworkers to respond.

A discrete soil collapse event is normally progressive in nature. First an uppermost portion of a trench wall caves off, and drops straight down like a slice off a block. When I am in a trench, even a shallow one, I am ever vigilant for this first increment. Falling from the maximum height it is moving fairly fast by the time it reaches the trench bottom. In injury events, it typically traps the feet and prevents trench egress. The collapse progresses to involve soil volumes coming from further down the wall and further back: lower velocity but far more weight and volume than the first increment. The progression commonly ends with a maximum increment.

This leaves remaining vertical wall sections unsupported at the margins of the collapse. Subsequent collapse of these vertical sections is a substantial hazard for rescue workers. 60 percent of fatalities in trench rescues involve would-be rescuers.

OSHA standards require trenches deeper than 5 feet to be shored. Shallower trenches can still be the site of fatal soil collapse, especially if workers are not standing upright. Movable temporary shoring is available within the construction industry. An alternative is to excavate sloping or terraced sidewalls. Due to vibration, heavy equipment should not be left running in proximity to occupied trenches. Interior trench corners are particularly susceptible to collapse and deserve particular caution.

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Don't Dig Too Deep

Historically, there have been between 100 and 300 people killed in the United States every year due to trench collapses. Jordan Barab covers these trench hazards in his worker safety blog, Confined Space.

On Friday, a worker in Georgia was trapped for two hours, briefly up to his neck, when the trench he was working in collapsed. Last word was that he survived, but the extent of his internal injuries had not been assessed. He is in my prayers.

It is a strong man, and lucky to boot, able to breathe under the crushing dead weight of soil. When soil drops, it quickly gains sufficient momentum to slam the air out of most folks. Against the weight of soil, there can be no place to expand the lungs. Even a person buried below his chest may still be grave danger. Where the soil reaches the diaphragm level, and settles in a form that has pushed the abdominal contents into the chest cavity, the effect on breathing can be the same as confining the chest.

Soil walls may collapse multiple times, or in phases, in the same trench. 60 percent of fatalities in trench rescues involve would-be rescuers. Soil collapse related deaths are both work-related and recreation-related, and all too often include children. The beach is a repeated setting of concern (from a story apparently no longer up at WebMD):

Safety Note for Beachcombers: Don't Dig Too Deep

Sand Holes Collapse, Suffocate Toddlers, Children, Even Adults

By Jeanie Davis
WebMD Medical News

Reviewed by Dr. Jacqueline Brooks

April 17, 2001 -- Sharks, skin cancer, drowning -- was a day at the beach ever a picnic? What's left, just digging holes in the sand? Maybe not. With beach season drawing nearer, two researchers report that several children -- and young adults -- have died when sand holes got a bit too deep and suddenly collapsed on them.

“There actually is the potential for catastrophe," says Bradley A. Maron, a second-year medical student at Brown University School of Medicine in Providence, R.I. The paper, which he co-authored with his father, Barry J. Maron, MD, of the Minneapolis Heart Institute Foundation, appears in this week's Journal of the American Medical Association.

In their paper, the Marons document seven cases of sudden- and near-death experiences involving beach holes.

The Marons' study began four years ago -- during a vacation at Martha's Vineyard -- when they witnessed a beach-hole incident that triggered their study of the phenomenon. "It was an 8-year-old girl, under the sand for seven minutes before rescuers could get to her," he tells WebMD. She survived, says the younger Maron.

He spoke with the beach rescue team afterward: "They said without question it seems to happen with greater frequency than is realized," Maron tells WebMD. He began watching CNN for similar news accounts and made follow-up phone calls for details.

Six of the seven incidents he documented since 1997 took place on public beaches -- all on the Atlantic coast -- mostly involving children, says Maron. In five cases, the holes were being dug by hand or using toy beach shovels. In two instances, people were inside holes they had found.

In each instance, Maron says, the person suddenly became completely submerged by sand when the walls of the excavation unexpectedly collapsed.

"The biggest complication in rescue efforts," Maron tells WebMD, "is that the sand appears undisturbed after the hole caves in, so rescuers don't know exactly where the person is. And they have to dig with their hands, for fear of hurting them with shovels. They just can't get to them in time." Four people among the cases were submerged for long periods of time -- 15 minutes to an hour -- and could not be resuscitated.

In one case, a 21-year-old man vacationing in North Carolina dug a nine-foot-deep hole. "He was down in the hole, just lounging in the chair when suddenly and unexpectedly it collapsed on him," says Maron. "It was catastrophic immediately. He had to be removed by bulldozer." Rescuers attempted CPR, but the man died.

Three people survived -- including one who experienced hypothermia and shock -- after lifeguards or other bystanders frantically dug an air pocket around their mouths and noses.

"Parents feel safe with their kids right by their side," Maron tells WebMD. "But they may not be attuned to what's going on. And afterward, people are so shameful of themselves. Of course it's not their fault; it's an accident, but it's absolutely preventable. It just takes common sense."

This phenomenon was news to at least one beach rescue team member, but he's not surprised.

"A lot of times you see kids digging up to waist deep, and that can be just as hazardous as head-deep," says Sean Gibson, a paramedic with New Hanover Regional Medical Center, which services the beaches in Wilmington, N.C.

"A cubic foot of sand weighs much more than you would think, and there's no way that child could get out," he tells WebMD. "And nobody would be able to hear that child either."

Adults should know better than to take the risk, says Gibson. And parents should be watching their children more closely. But if children do get into this situation, here's good news. "With toddlers and children, you should be able to get to them fairly quickly if you see it happening."

Although sand dunes don't exactly fall under the Occupational Safety and Health Administration's jurisdiction, OSHA certainly recognizes trenches of all shapes and sizes as hazards, says H. Berrien Zettler, deputy director for construction.

OSHA has investigated 24 fatalities resulting from cave-ins in the last year alone, he tells WebMD. "It's a serious issue. People don't realize that dirt, or sand for that matter, is extremely heavy. It makes it impossible for people to exercise their abdominal muscles to draw in air; essentially, they suffocate."

The sheer weight of sand causes the collapse, says Zettler. "And people don't have to be completely covered with it to suffocate. Chest deep could be enough to do it -- you just can't draw air. If you're sitting down, it takes even less -- just two or three feet of sand -- to cover your chest."

Although wet sand looks hard, it's actually extremely unstable, because nothing is holding it together, says Zettler. "There's no cohesion like you find in clay soil. You dig into it, and it's like a liquid."

Be careful out there. Keep an eye on our children.

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