An excavation is defined as any dug-out area of ground other than a trench, tunnel or excavated shaft as a result of removing material. A trench is an elongated dug-out area of land in which its depth exceeds its width. Trenches can be extremely dangerous with significant hazards that must be controlled in order to perform work safely.

Common hazards associated with this work include location of site, surrounding property, structures and people in and near the site, overhead clearance for machinery, weather conditions, ground conditions and amount of time the trench or excavation will be exposed for.

One of the biggest risks of working in a trench is the potential for a cave-in. When the walls of a trench suddenly collapse, soil can quickly fill the excavated space, exerting tremendous pressure on anything in its path.

Cave-ins and slough-offs are a major cause of deaths in the construction industry each year. Excavations must be properly shored or cut back to an acceptable angle of repose; otherwise, there will be a constant threat of a cave-in and the associated chance of injury or loss of life. A qualified person must be involved in planning and having a safe excavation project.

Before Excavation Review
Underground utilities located? (Checked with local utility companies or property owner.)
– Any overhead hazards (i.e., falling rock, soil, or other materials or equipment)?
– Will there be any heavy equipment operating in the near proximity of the excavation?
– Estimated depth required for the excavation?
– How many people will work inside the excavation?
– Is there an escape plan for those inside the excavation to cover a possible cave-in or slide?
РHas there been a soil analysis? This will help determine the type of shoring to provide or the angle  of repose needed.

Steps to Take to Provide a Safe Excavating Operation
– Always shore or cut back the opening adequately.
– Any opening with a depth of five feet or more requires shoring or be cut back.
– Never store excavated or other materials closer than two feet from the edge of the excavation.
– Inspect the excavation daily. This must be done by a competent person.
– Access ladders must be provided every twenty-five foot in excavations of four (4) foot or more in depth.
– Review escape procedures with all personnel who may have cause to be in the excavation.

Additional Discussion Notes:
– Possible gas accumulation in the excavation?
– Barriers, guardrails or other safety warnings in excavation area?

Remember: Unlike most accidents, the cave-in of an excavation usually can be predicted if closely watched. It is, therefore, critical that a competent person keeps a close eye on any excavation. Everyone should be removed from the excavation area should it appear to be unstable.