Trenching

Hazard:

Trench collapses cause dozens of fatalities and hundreds of injuries each year. In 2003, the highest level of trenching deaths occurred. This resulted in an industry wide examination of the hazard and immediate solutions to mitigate. The following year, trenching accidents and deaths decreased significantly; however, trenching deaths have been steadily increasing each year this past decade.

Solutions:

• Never enter an unprotected trench.
  Always use a protective system for trenches 5 feet deep or greater.
• Employ a registered professional engineer to design a protective system for trenches 20 feet deep or greater.
• Protective Systems:

• • Sloping to protect workers by cutting back the trench wall at an angle inclined away from the excavation not steeper than a height/depth ratio of 11 2:1, according to the sloping requirements for the type of soil.
  • Shoring to protect workers by installing
    supports to prevent soil movement for
    trenches that do not exceed 20 feet in depth.
  • Shielding to protect workers by using trench boxes or other types of supports to prevent soil cave-ins.
• Always provide a way to exit a trench- -such as a ladder, stairway or ramp–no more than 25 feet of lateral travel for employees in the trench.
• Keep spoils at least two feet back from the edge of a trench.
• Make sure that trenches are inspected by a competent person prior to entry and after any hazard-increasing event such as a rainstorm, vibrations or excessive surcharge loads.