Working in trenches poses significant hazards, primarily cave-ins, which can trap or crush workers. Other hazards include falling equipment or excavated soil, falls into the trench, flooding, and exposure to hazardous atmospheres. [3]

To prevent cave-ins, OSHA requires sloping or benching the sides of the excavation, shoring the sides, or using a trench shield. [1]

Key safety precautions include:

• Protect workers from cave-ins in trenches 5' or deeper, and in shallower trenches where a cave-in hazard exists, by using shoring, trench boxes, or sloping.
• Provide ladders in trenches 4' or deeper.
• Identify and support underground utilities.
• Ensure workers wear high visibility clothing when exposed to vehicle traffic and use appropriate work zone signage.
• Keep spoils back a minimum of 2' from the trench edge.
• Stabilize undermined adjacent structures.
• Protect employees from water accumulation.
• Do not allow employees to work under suspended or raised loads or materials.
• Conduct pre-job planning and inspections of trench worksites.

[2] A competent person must inspect the trench worksite, including the soil protective system, before work starts and after any hazard-increasing changes, such as a rainstorm. [2]

Trenches more than 20 feet deep must be designed by a registered professional engineer. [2]

OSHA also authorizes Compliance Safety and Health Officers (CSHOs) to initiate inspections whenever they observe an open trench or excavation. [4]