Trench Safety Difference-Makers: The Perspective of a First Responder
In any trench situation, you need a Trench Competent Person and to notify nearby local fire/rescue teams.
- By Tim Robson
- Aug 01, 2020
I will never forget the anguish in that grandmother’s voice as she pleaded with us to save her sixteen-year-old grandson who was trapped under nine yards of soil that had collapsed from an unprotected trench wall. Unfortunately, my rescue crew was unable to save him. It was not the first time that I had to tell someone that I was sorry for their loss.
Trenches are Inherently Susceptible to Collapse
This unfortunate incident was totally avoidable. If the contractor had adhered to the well-documented guidelines and a few very easy-to-follow laws, that young man would not have lost his life that day. The laws exist because trenches are inherently susceptible to collapse, and an unprotected, open trench is a hazard, no matter how stable it looks. I have responded to numerous excavation/trench emergencies and to this day, it still amazes me that so many employers willingly decide to allow unprotected trenches to be entered even though there are state and federal laws that require them to be rendered safe before anyone sets foot in one.
Two Difference Makers
There are two things that I see as difference-makers, when I look back at the numerous trench emergencies I have responded to over the years. First, it is absolutely essential to have a Trench Competent Person’s involvement from the planning stages onwards. The Competent Person needs to be involved in the soil evaluation, the selection of appropriate protective systems, as well as the daily pre-entry inspections of the trench. This Competent Person has to have documented, trench-specific training and knowledge. And this person must have the authority to stop work when unmitigated hazards exist. In 86 percent of trench cave-in fatalities, there was no Competent Person present, so that is a good indicator of how much a Trench Competent Person can be a difference-maker in trench safety.
Second, it’s always a good idea to give advance notice to the local fire/rescue team of the scheduled trench work. Find out where the nearest station is and pay them a visit. They will appreciate the heads-up, and knowing about your project will help them prepare mentally for the possibility of a rescue. They may have knowledge of the jobsite or know of resources that will be helpful to you. It’s important not to let this notification lull you into a false sense of security (more on this topic later). Prevention is the best approach.
The Physics and Forces of a Trench Collapse
There is a common misconception that the majority of trench collapse victims succumb to suffocation and airway obstruction injuries. However, traumatic injuries and crush syndrome are a leading cause of death due to the large impact forces generated by a vertical trench wall collapse. Even people who have spent years working in trenches often do not realize how great these forces are until it is too late. A combination of Type B and Type C soils weighs approximately 110 lbs. per cubic foot and a trench wall collapse could easily involve four to six yards of soil, which could weigh as much as a large pickup truck. The average trench is six feet deep and by the time the collapsed soil reaches the bottom of the trench, it is travelling at forty-five miles an hour. Any workers inside the trench area are now impacted by a pickup truck travelling 45 miles per hour, and the last time I checked, this does not make for a positive outcome.
“Everyone has a great plan until they get punched in the face” is a saying that I use in every rescue class that I have taught, and I feel that it is especially appropriate when it comes to trenching emergencies due to the time-consuming and coordinated effort a trench collapse emergency demands. Most fire departments have limited trench rescue capabilities due to the cost, size and large quantity of the minimum emergency shoring equipment required. That’s why it is the employer who must ensure that trained trench rescuers with proper trench rescue equipment are readily available, especially if there is a potential for the presence of a hazardous atmosphere in the trench.
While it’s a good idea to notify the local fire department in advance of any trench/excavation activity, you should not expect them to be on “stand by” while workers are actively entering a trench. Most fire departments do not have the necessary specialized training and committing resources to be on “stand by” negatively impacts their ability to respond to the everyday “911” call volume. Firefighters and first responders do what they do because they want to help people, and notifying them helps prepare them mentally, at a minimum, and it may also allow them to alert their heavy rescue team, if they are well-resourced. They will come to your aid and do all they can, but prevention is a far better “survival strategy” as you will see from typical rescue response time frames.
Anyone who is involved in trench work should understand these time frames, and perhaps reset their expectations for rescue operations after trench collapses. I will break down how long it could take a well prepared and trained rescue team to render a collapsed trench wall safe so that rescuers may enter the trench and start the removal of soil from on top of the trapped victims:
If a Collapse Occurs
Notify “911” and hope that the local response entity is trained in trench rescue (10 mins). Then the rescue team arrives on scene and starts to formulate plan of action (15 mins):
- Trench lip stabilization (ground pads and spoil pile removal)
- Ladder in the trench
- Atmospheric monitoring
- Victim location
- De-watering trench
- Support utilities
- Shutdown any hazard causing equipment (back hoes, excavators, generators etc...)
- Rescue equipment staging
- Rescue team competent person performs a trench pre-entry checklist
After that, a plan of action is reviewed with all members (10 mins):
- Entry team members identified
- Panel team members identified
- Strut team members identified
- Incident Commander identified
- Safety Officer identified
Then, Trench Panels are installed in trench with rescue struts (10 mins). Rescuers enter trench and start to remove soil entombing victim (30 mins) and the victim is packaged and removed from trench (10 mins).
Total time is one hour and 25 minutes (minimum time for well-trained and equipped team).
The above timeline is for a straight trench with the average dimensions of six feet deep and four feet wide and does not take into consideration the following time-consuming conditions that can be commonly found in everyday trenching that can easily hinder the ability for a positive rescue outcome:
- “L” or “T” intersecting trenches
- Damaged sewage, water, natural gas pipelines
- Atmospheric hazards
- Vehicle in the trench
- Multiple victims
- Trenches greater than 10 feet deep
- Undermining of structural foundations
- Inability to control external surcharge forces such as runways, trains, freeways
- Victims pinned by construction materials that fell into the trench
I hope that this article sheds some light on the rescue response requirements and the immense pressure that is placed on rescue teams, whether trained or untrained, that is unduly assumed because of an employer’s willingness to circumvent state and federal trench safety laws. Getting into a trench that has not been deemed safe by a Competent Person immediately prior to entry, or (even worse) getting into an unprotected trench is like playing Russian roulette. Don’t risk the safety of your team or local first responders by taking shortcuts with trench safety.
This article originally appeared in the August 2020 issue of Occupational Health & Safety.