As we frequently write about in Lifelines, the risk of cave-ins and collapses makes excavation and trenching among the most potentially hazardous construction operations. Recent fatality data released by OSHA indicates cave-ins and trench collapses killed at least 22 construction workers in 2017 and 2018, a figure likely to rise with the completion of more fatality investigations. Properly installed support systems such as sloping, shoring and shielding can reduce the risk of cave-ins and collapses. However, these aren’t the only hazards that must be addressed to keep workers safe.
At least nine other deaths related to excavation and trenching occurred over the last two years that had nothing to do with poorly reinforced walls. These include an employee crushed by a storm pipe that was being lowered into a trench, a worker killed during disassembly of a trench box and another who drowned when a water pipe broke, causing the excavation to flood. In British Columbia, another tragedy was averted when five construction workers digging trenches in the basement of a large building developed breathing difficulties and were taken to a hospital, where it was determined they were suffering from nitrogen dioxide (NO2) poisoning. NO2 is a toxic byproduct created when fossil fuels like coal and oil are burned at high temperatures.
“What makes these injuries and fatalities especially tragic is that every single one could have been prevented,” says LHSFNA Management Co-Chairman Noel C. Borck. “A safety program that educates employees on how to identify and avoid hazardous situations, trains them to report what they find and empowers them to feel comfortable stopping work until the hazard is corrected can make all the difference in ensuring that workers who descend into trenches also come out safely.”
Hazardous situations include, but are not limited to:
- Lack of support systems that reduce the risk of cave-ins or collapses
- Hazardous atmospheres, which can include oxygen-deficient environments, flammable/combustible/explosive environments and toxic environments
- Inadequate ladders, steps or other means of access and egress
- Equipment or excavated soil stored at the edge of the trench
- No barriers to prevent falling into the trench or excavation
- Flooding or standing water accumulation in the trench
- No ventilation system or respiratory protection (if the trench is a confined space)
- Lack of high visibility vests that can reduce the risk of being struck or crushed by large machinery
What Must Employers Do to Reduce Hazards?
Before any excavation or trench work gets underway, there are a number of steps an employer must take. These include:
- Identifying soil type(s) where digging is to take place. (Soil type can change from top to bottom and along the length of a trench).
- Locating buried services and overhead power lines and ensuring they are de-energized as necessary and that emergency contact information is accessible.
- Following OSHA’s excavation standard (1926.52) for protecting workers and ensuring all trenches and excavations are sloped/benched, shielded or shored.
Note: Excavations over 20 feet deep require the use of a professional engineer.
OSHA requires that employers designate a competent person to inspect trenches and excavated areas daily and as conditions change to ensure they are safe to enter. This includes:
- Testing for oxygen and hazardous gas before workers enter the area and throughout the workday as required.
- Ensuring safe access and egress with ladders, steps or ramps when excavations are four feet or deeper.
- Ensuring water is removed from the excavation.
- Checking areas adjacent to the site for potential hazards that can impact the stability of soil. (Nearby traffic can cause soil to vibrate and collapse and nearby buildings can put pressure on trench walls.)
The competent person also:
- Ensures barriers and warning systems are in place that protect workers, pedestrians and equipment from falling into the excavation.
- Implements good housekeeping practices that include moving debris and excavated soil away from the excavation site daily.
Excavation and trenching fatalities are preventable and the LHSFNA can help LIUNA signatory contractors ensure their job sites don’t become the scene of an avoidable tragedy. Order the Fund’s Safety in the Trenches booklet and our new Excavation and Trench Safety toolbox talk for more information about protecting workers who enter trenches. To request assistance related to trenches and excavations, or for other safety and health questions or concerns, call the Fund at 202-628-5465.
[Janet Lubman Rathner]