By Emily Newton
Trenching is a necessary practice when doing work that occurs partially underground. However, it can also be extremely dangerous due to the risk of cave-ins. Dirt is extremely heavy, so it could trap workers and cause asphyxiation. However, people can reduce the threats by taking trenching safety seriously. It is also wise to have a trenching safety program emphasizing how staying safe is everyone’s collective responsibility. Here are some specific tips to consider.
Ensuring only workers with the appropriate training and experience do excavation work is essential. The Occupational Safety and Health Administration (OSHA) requires that each trenching job has specific people overseeing it — they are:
- Competent Person: Someone who can spot the current and predictable hazards in an environment or its working conditions. They must also have the authority to eliminate them. This person is also the individual who permits specific workers to enter trenches.
If the trench is less than 5 feet, protective systems get installed at the competent person’s discretion. Then, if the trench is between 5 and 20 feet, the competent person is the designated individual to supervise the installation of protective systems.
- Qualified Person: OSHA defines this individual as someone who has successfully demonstrated their ability to solve and resolve issues that arise during a task, job or project. They either show this characteristic with a degree, certification, professional standing, or extensive training, knowledge and experience. A qualified person must oversee protective system installation when the trench is 20 feet or more.
You may not have immediate access to people meeting these descriptions on your site. In that case, outsourcing is a smart move. People in other industries have recognized outsourcing is valuable and cost-effective, particularly during high-demand periods. Given the high-risk nature of trenching, people should always take time with the process and never try to cut corners by assigning duties to those without the proper training.
Outsourcing is an excellent way to cope with operational struggles associated with trenching or other construction necessities requiring specialized knowledge. However, a related part of trenching safety involves vetting candidates to ensure they are well-qualified before hiring them.
Many recommended safety practices retain an easy-to-remember format — such is the case with the three S’s. Some protective systems fall under the three S’s.
People must dig trenches according to the correct slope for the soil type. Soil gets categorized as stable rock — such as granite or sandstone — or grouped as category A, B or C, in order of decreasing stability. A good rule is the slope angle should decrease along with the soil stability. However, a vertical slope suits the trench if the surrounding walls are stable rock.
OSHA requirements dictate that a qualified person assess the soil and rock to determine how long it will stand under the weight. An alternative is to group it under category C and take the appropriate measures to maintain trenching safety in the least-stable soil.
This step involves using the necessary shoring equipment to provide extra wall support and prevent a trench collapse. Timber piling and hydraulic jacks are a couple of the methods used that allow crews to work in or near trenches without the risk of a cave-in.
A professional engineer must direct the shoring design if the trench is more than 20 feet deep. That is also a requirement when the excavation is near roads, bridges and buildings, or there is heavy or stockpiled equipment near the excavation. The professional engineer will examine all site factors to recommend the best shoring plans.
Another protective measure involves using trench boxes for shielding. Unlike shoring, shielding does not prevent trench wall collapses. Instead, it safeguards workers from the soil’s weight if an accident happens.
That is critical since it can weigh more than 100 pounds per cubic foot. If you look at that another way, it means soil spanning the size of an office desk could collectively weigh as much as a car. The three S’s should factor into any comprehensive trenching safety program.
It is becoming more common for safety managers and others to investigate newer technologies and see how they could improve worker well-being. Miners are similar to professionals who often work in trenches because both groups understand the hazards of underground work. The mining industry has adopted smart sensors that can detect the structural integrity of surrounding walls, flagging a possible collapse before it happens.
There has yet to be anything specific for trenching safety. However, applying previous work to that task could be relatively straightforward. In one case, people developed Bluetooth low-energy beacons to detect if unauthorized people went to certain parts of a construction site.
Statistics indicate 39 fatalities occurred from trenching and excavation work in 2022. That sobering finding is a potent reminder that terrible things can happen even when people know best practices and follow a trenching safety program. So, looking at ways to make additional improvements — such as using smart sensors for workers — is vital.
Beyond innovative products, decision-makers should examine options that could reduce or eliminate the need to use trenches. One possibility is trenchless sewer repair for underground pipes. It emerged in the 1970s, so it is not new. However, this alternative is less-invasive than conventional methods and is often more efficient. More importantly, it is generally safer because it requires significantly less digging.
The main idea is to stay aware of options that support or could reduce the need for conventional trenching while aiming to do the traditional method as safely as possible. One excellent way to uphold that ideal is for site leaders to encourage workers to speak up about anything that seems unsafe — regardless of its relation to trenching. People should encourage workers to suggest any improvements to the trenching safety program, too, indicating the value of their input.
Trenching is a significant part of work that occurs underground. However, it also comes with numerous risks that people must mitigate. Treating safety as a constant concern will make trenching less dangerous for everyone involved.
Emily Newton is a construction and industrial journalist. She is also the Editor-in-Chief for Revolutionized Magazine. Keep up with Emily by following her by subscribing to Revolutionized’s Newsletter.