Just because a trench is less than 5 feet deep does not mean it is safe to enter. Many people have been seriously injured by shallow trench wall cave-ins. Injuries include broken legs, ankles, hips, etc. What employers often forget is dirt weighs between 90 and 120 pounds per cubic foot or approximately 3,000 pounds per cubic yard. When a couple or more cubic feet falls from a 4 or 5-foot deep wall of dirt and strikes a worker, serious injury often occurs. Keep in mind that the dirt walls may also contain rocks and rubble which can add to the problem. While a person may not be buried overhead, they can still be injured and/or trapped. More so, a person does not have to be buried overhead to be fatally injured.
The OSHA Excavation Standard – Subpart P is not all about fatalities. Like all OSHA regulations, Subpart P is about preventing injuries and fatalities.
OSHA requires employers to train and designate a competent person (CP) for all trench or excavation work. The CP must make inspections daily and as needed for every trench or excavation a worker may have to enter no matter how deep it is. What this means is the CP overseeing trenches less than 5 feet deep must make an inspection to determine if it safe to enter. If the CP determines it is not safe to enter because the wall does not appear to be stable, action must be taken to make it safe before anyone can be permitted to enter the trench.
For example, take a trench that is 4.5 feet deep with soft wet walls or in sandy soil. Even soils that are Type A can be a problem. Trench walls that have a good possibility of caving in must be made safe. Situations like this must be addressed by the CP to ensure worker safety. For example, the CP could have a small trench box or some aluminum hydraulic shoring installed, or simply have the equipment operator cut back the walls of the trench. There are no specific requirements established for trenches less than 5 deep, but something must be done to make them safe.
For shallow trenches, lightweight modular trench boxes that can be lifted and moved with a rubber-tired backhoe or mini excavator are available for sale or rent. In addition, several manufacturers of single cylinder aluminum hydraulic shores have tabulated data which permits the use of one single shore every 4 to 8 feet to brace the walls of up to a 6-foot-deep trench depending on soil type. In questionable situations, why take a chance? Provide one of the many simple protective systems that are available.
Believe it or not, during my 30 years working for NUCA I have heard stories about workers being killed in trenches that were only 2, 3, 4, or 5 feet deep. Not common occurrences, but someone lost their life because the trench was shallow and they did not think it was unsafe. On the other hand, I have heard many instances of workers being seriously injured when a shallow trench cave-in occurred.
Take for example, a young man named Jordan Baughn, the son of a contractor and supervisor on a job laying storm drain. The job was only 3 feet, 9 inches deep. While the next stick of pipe was being installed Jordan took a break and when he did the trench wall caved in on him and nearly killed him. Fortunately, he survived and will be OK after months of recovery. For more information about this cave-in see the YouTube video at https://youtu.be/mjBBmzlKjKg or search YouTube for How Jordan Baugh Was Almost Killed in a 3’9” Deep Trench.
Although most trench fatalities occur in trenches 5 to 15 feet deep, trenches less than 5 feet in depth can also be dangerous. Some states have a 4-foot rule requiring trenches 4 feet or more in depth must be equipped with a trench protective system. In addition, I have met many NUCA members who have established their own 4-foot rule. Even still let’s not forget workers like Jordan at 3 feet, 9 inches.
Lives are at stake and it is important to remember that a trench that is not equipped with a trench protective system is dangerous. Therefore, every trench or excavation must be inspected by a CP and that person is responsible for determining what needs to be done to ensure that the trench is safe to enter no matter how deep it is. Not all shallow trenches have to be shored or equipped with a trench box, but it never hurts to at least slope the walls back even if they appear to be stable.
George Kennedy is Vice President of Safety for the National Utility Contractors Association (NUCA) and is a Certified Safety Professional (CSP).