According to the National Institute for Occupational Safety and Health (NIOSH), over the past three decades roughly 3 workers a month have lost their lives in a trench collapse. Excavation and trench safety is critical as they are among the most hazardous of all construction operations.

OSHA Excavation Standards

The Occupational Safety and Health Administration (OSHA) has a set of standards in 29 Code of Federal Regulations (CFR) Part 1926. Most importantly, employers must comply with these trenching and excavation requirements.

An Excavation or a Trench?

An excavation is any man-made trench, cut or cavity in the surface of the ground formed by earth removal. The definition of a trench is a narrow excavation made below the surface of the ground. In general, the depth is greater than the width, but the width of a trench (measured at the bottom) is not greater than 15 feet.


Cave-ins while trenching are the most likely cause and pose the greatest risk to construction workers. In fact, one cubic yard of soil typically weighs nearly that of an automobile. So, never enter an unprotected trench. Other hazards include falling, hazardous atmospheres, and accidents from mobile equipment.

Protective Systems

OSHA has general rules to protect workers from cave-ins including:

  • Sloping and benching the sides of the excavation;
  • Shoring the sides with mechanical or hydraulic systems; and,
  • Shielding with trench boxes or supports to prevent soil cave-ins.

Other means of worker protection involve:

  • Keeping heavy equipment away from the edges of a trench;
  • Store excavated soil (spoils) and other material away from trench edges;
  • Test for atmospheric hazards (such as low oxygen or toxic gases);
  • Inspect trenches regularly and after changing conditions; and
  • Ensure personnel wears appropriate, highly visible clothing.

For further information on OSHA Trenching and Excavation Safety, please get the PDF from their website located at