|  | Public Health Safety | Work Safety

OSHA Trench Safety

An average of 54 fatalities occur on construction sites each year as a result of trenching and excavation accidents, according to the National Institute for Occupational Safety and Health. Cave-ins are the most well-known excavation hazard, but workers can also face asphyxiation, inhalation of toxic fumes, drowning or electrocution by underground wires. Most excavation hazards are preventable if workers and management follow the guidelines set forth by the Occupational Safety and Health Administration to address the most common causes of excavation injuries.

  1. Protective System

    • Excavations are dangerous in part because trenches are inherently unstable, making protective systems that stabilize the trench and support the edges very important. In order to comply with OSHA's requirements for protective systems, a qualified person must evaluate the soil, and then choose and correctly construct an appropriate protective system. The correct protective system depends on the type of trench and can include an appropriately sloped trench wall or shoring the edges with either timber or aluminum.

    Inspection

    • OSHA requires each site and protective system to be inspected by a qualified individual who has the authority to immediately eliminate hazards. An excavation site should be inspected before construction begins, before each shift and following rainstorms or any other event that could compromise the safety of the trench, such as a heavy piece of equipment that was driven too close. The person inspecting the site must be trained in soil analysis, protective systems and OSHA requirements.

    Spoils Placement

    • Materials, or spoils, excavated from the site can cause a cave in or can fall back onto the workers in the trench if they are placed too close to the edge. Spoils and equipment must be placed at least 2 feet from the edge of the trench and/or a retaining device must be used, such as a trench box, which extends above the rim of the trench to prevent objects from falling back in. If the location of the site does not allow for objects to be placed 2 feet back from the edge of the trench, the items are required to be moved temporarily to another location.

    Entrance and Exit

    • To avoid injuries entering and exiting the trench, ladders, stairways or ramps are required in all sites 4 feet deep or more. Structural ramps used for entering and exiting a trench must be designed by an experienced person and each worker must have an exit route within 25 feet.

    Planning Ahead

    • Since every trench and site location is different, planning ahead is vital to worker safety. Utilities should be contacted prior to digging to locate underground lines; tests should be done for low levels of oxygen and toxic fumes in the trench so adequate ventilation or respiratory devices can be provided; plans to prevent water accumulation must be in place; and excavation sites should be kept open the least amount of time possible.

Work Safety - Related Articles