Inspectors from the Ontario Ministry of Labour (MOL) will be conducting a safety blitz of excavation projects in May.

The blitz is part of the province’s Safe At Work strategy aimed at raising awareness of the hazards involved in trenching and excavation work and also to prevent injuries and illnesses that could arise from unsafe work practices.

Inspectors will be looking to ensure that employers and workers are complying with health and safety legislation.

During the blitz, inspectors will be targeting the following types of excavation projects:

  • Trenching to install or repair services such as natural gas, electrical, telecommunications and sewers.
  • Construction of foundations.
  • Digging basements for residential housing.
  • Soil retention projects such as stabilizing soil in an excavation.
  • Installation of forming or footing supports for the construction of buildings or bridges.
  • Road construction and repair projects involving excavation.

According to the Infrastructure Health and Safety Association (IHSA), trenching and excavation work is inherently dangerous in construction.

The IHSA says that too often people think that such jobs are not hazardous enough to require safeguards against collapse.

Unless the walls are solid rock, the IHSA says workers should never enter a trench deeper than four feet if it is not properly sloped, shored or protected by a trench box.

One of the biggest hazards related to trenching and excavation is the risk of cave-ins, according to the IHSA.

Most fatal cave-ins occur on small jobs of short duration such as service connections and excavations for drains and wells.

An unstable trench or excavation can collapse, killing or injuring workers by suffocation, or crushing when a worker is buried by falling soil.

The IHSA says 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
  • excessive weight near the trench
  • adjacent buildings and structures
  • existing foundations
  • previous excavations or soil disturbances

The IHSA says there are three basic methods of protecting workers against trench cave-ins. They are:

  • sloping
  • shoring
  • trench boxes