As Trench Safety Month comes to an end, it's important to reflect on the 13 lives lost in trench accidents so far this year. Trench fatalities are preventable. Data shows some jobsites where workers were injured or killed had the proper protective equipment on-site, it just wasn’t being used. Consequences of poor safety practices include not only loss of life, but also hefty fines and lengthy legal proceedings for those not adhering to Occupational Safety and Health Administration (OSHA) regulations.
Cave-ins can be caused by vibrations, stress loading the soil, excavated materials located too close to the trench and failure to inspect the trench before each shift and after weather events. Benching, sloping, shoring and shielding are methods of protecting workers from cave-ins, with sloping being the most common. It's vital to use the right protection system for the job. Trench protection equipment can be rented, sparing contractors the initial cost of purchasing, and moving and storing the equipment when not in use.
Site managers should ensure all trenches are inspected before workers enter. OSHA requires that all trenches are inspected at least daily by a “competent person.” This person is defined as “an individual who is capable of identifying existing and predictable hazards or working conditions that are hazardous, unsanitary, or dangerous to workers, soil types and protective systems required, and who is authorized to take prompt corrective measures to eliminate these hazards and conditions.”
Trenches should be inspected even when they are less than 5 feet deep — 1 cubic foot of soil can weigh 74 to 110 pounds, depending on if it’s wet or dry, so even small trenches must be inspected. Trenches 20 feet or deeper require protective systems designed by a registered professional engineer.
Protect your employees from trench cave-ins with the following tips from OSHA:
- Keep heavy equipment away from trench edges.
- Identify other sources that might affect trench stability.
- Keep excavated soil (spoils) and other materials at least 2 feet from trench edges.
- Know where underground utilities are located before digging.
- Test for atmospheric hazards such as low oxygen, hazardous fumes and toxic gases when greater than 4 feet deep.
- Inspect trenches at the start of each shift.
- Inspect trenches following a rainstorm or other water intrusion.
- Do not work under suspended or raised loads and materials.
- Inspect trenches after any occurrence that could have changed conditions in the trench.
- Ensure that personnel wear high visibility or other suitable clothing when exposed to vehicular traffic.
