There is a reason that trenching is considered one of the most hazardous of all construction operations. Trench failures can happen suddenly, without warning, leaving workers with little – if any – time to get out of the way. And while a small amount of dirt may not seem like a big threat, as little as one cubic yard of dirt can weigh more than 3,000 pounds.
While cave-ins are the most cited trench-related threat, they are by no means the only cause of injury. From falls to hazardous atmospheric conditions, any number of hazards can combine to put your workers at risk for injury. However, this does not mean that you are powerless to prevent them. By ensuring that you have the right knowledge and regulations in place, you have the power to dramatically reduce the risk of trench-related injury. Read below for a few tips on increasing trenching safety awareness.
Never Enter an Unprotected Trench
OSHA defines a trench as a narrow “underground excavation that is deeper than it is wide, and is no wider than 15 feet (4.5 meters).” It is important to note that, given enough time, just about any trench will eventually collapse. Unfortunately, all too often, the short-term apparent stability of a trench has tempted many workers into an unprotected trench.
Remember, even if a trench looks stable, the risk of a cave-in or other disaster is always imminent. In fact, according to the U.S Bureau of Labor Statistics, most trench excavation related accidents occur when:
- Trenches are between 5 feet to 14 feet deep
- The collapse develops extremely fast
- No protective system is in place
Protected Trench Requirments
The good news is that many trench related fatalities are entirely preventable. According to the U.S. Bureau of Labor Statistics, a lack of protective system remains the leading cause of these fatalities. This statistics is somewhat alarming when you consider that OSHA requires all trenches 5 feet or deeper to make use of one of the following protective system options:
- Sloping the Ground: Sloping protects workers by cutting back the trench wall at an angle inclined away from the excavation.
- Benching the Ground: Similar to sloping, benching includes having steps cut into the sides of the trench.
- Shoring the Trench: Shoring supports the walls of the trench through the installation of aluminum hydraulics or other types of supports.
- Shielding the Trench: Shielding involves trench boxes or trench shields that are placed in the excavation to prevent the sides of a trench from caving in.
Take note: depending on the depth of the trench and the grade of materials, different trenches will require varying protective systems.
Inspecting the Trench Every time
It is also important to note that the conditions of a trench can change at almost any time. Even minor changes in weather or how a task is performed can have a dramatic effect on the overall stability and safety of the trench. For that reason, OSHA standards require that trenches be inspected daily and as conditions change by a competent person.
Examples of when the conditions of a trench can change include:
- At the beginning of a new task
- When there is a change in how a task is performed.
- If changes in soil conditions occur (e.g., after a rain event, alteration of approved excavation, etc.)
- A specific need or concern is identified
Remember, one of the biggest ways to prevent an accident is through continual reinforcement of safety awareness. Employers can help prevent injuries and deaths by frequently reminding workers of OSHA guidelines and posting signs that stress the dangers of trenching. For more information, Download a Copy of the OSHA Trenching and Excavation Fact Sheet.