Trenching and Excavation Safety Training

An excavation is a hole left in the ground as the result of removing material. A trench is an excavation in which the depth exceeds the width. Trenching and excavation work is inherently dangerous. Hazards include cave-ins, struck-by injuries, electrical contact, and slips, trips, and falls.

During the MOL’s excavation safety blitz, inspectors will be targeting the following types of excavation projects:

  • “trenching” (digging of long narrow excavations) to install or repair services such as natural gas, electrical, telecommunications, and sewers
  • construction of foundations
  • “soil retention” (stabilizing soil in an excavation)
  • digging basements for residential housing
  • forming “footing” (supports) for the construction of buildings or bridges
  • road construction and repair involving excavation.

One of the biggest hazards related to trenching and excavation is the risk of cave-ins. An unstable trench or excavation can collapse, killing or injuring workers by suffocation or crushing when a worker is buried by falling soil. Trench stability is affected by a number of factors such as:

  • improper use or installation of support system or trench box
  • soil type and moisture content
  • weather
  • vibration
  • depth of the trench
  • length of time the trench is left open
  • surcharge (excessive weight near the trench)
  • adjacent buildings and structures
  • existing foundations, and
  • previous excavations or soil disturbances.


There are three basic methods of protecting workers against trench cave-ins:

  • sloping
  • shoring
  • trench boxes

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