Are Excavations/Trenches Considered Confined Spaces? – Ask The Expert

Question

Do you know if a trench is definitely considered a confined space in BC’

Answer

It depends.

Explanation

The OHS Reg. definition of ‘confined spaces’ in Sec. 9.1 lists characteristics but not specific examples. However, the WorkSafeBC Guidelines specify that an ‘excavation’ is NOT a confined space if ALL of the following criteria are met:

  1. The design, construction, location, and intended use of these spaces will ensure these spaces are characterized by clean respirable air at all times.
  2. The space must have an interior volume of not less than 64 cubic feet per occupant.
  3. The space must have openings to the atmosphere that are known to provide natural ventilation.
  4. There must be no potential for a high or moderate hazard atmosphere, as defined in section 9.1 of the Regulation, to exist or develop immediately prior to any worker entering the space or during any work within the space.
  5. There must not be a need to mechanically ventilate, clean, purge, or inert the space prior to entry for any reason.
  6. There must be no potential for a hazardous substance to migrate through any media (e.g., air, soil, conveyance, piping, or structure) to infiltrate the space.
  7. The space must be free of residual material (e.g., waste, sludge, debris) that if disturbed could generate air contaminants that could immediately and acutely affect a worker’s health.
  8. There must not be any risk of entrapment or engulfment to workers entering the space.
  9. The space must not contain, have introduced, or be adjacent to tools, equipment, or involve processes that could generate air contaminants that could immediately and acutely affect a worker’s health