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157 Excavation Safety: Basic
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The Hazards

Trenching and excavation work presents serious hazards to all workers involved.

Many hazards exist in this photo. Are they all addressed?

Cave-ins pose the greatest risk and are more likely than some other excavation-related incidents to result in worker fatalities. One cubic yard of soil can weigh as much as a car. Employers must ensure that workers enter trenches only after adequate protections are in place to address cave-in hazards. Other potential hazards associated with trenching work include falling loads, hazardous atmospheres, and hazards from mobile equipment.

Excavation vs. Trench

Dig a hole in the ground and you've made an excavation. Excavations can be any size: wide, narrow, deep, or shallow.

A trench is a narrow excavation, not more than 15 feet wide at the bottom. If you install forms or other structures in an excavation that reduce its width to less than 15 feet, measured at the bottom, the excavation is also considered a trench.

  • If you work in an excavation that's five feet deep (or deeper) you must be protected from a cave-in.
  • If a competent person, who has training in soil analysis, determines that there's a potential for an excavation to cave-in, you must be protected regardless of its depth.

Knowledge Check Choose the best answer for the question.

1-1. A _____ is not more than 15 feet wide at the bottom.