This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply the law based on the facts in the workplace.

Hazard summary

We have recently been made aware of multiple incidents where the placement of materials or spoils from an excavation on a construction project may have been a contributing factor to either:

  • a critical injury
  • a fatality
  • significant property damage

In separate incidents, construction materials were placed in an area of a structure that likely could not withstand the forces applied when the material was placed, potentially contributing to the collapse of the structure. Another incident occurred when the spoils of an excavation were likely not compacted or otherwise protected, potentially causing the built-up berm to give way when heavy rain hit, potentially contributing to the in-rush of water into the trench, engulfing a worker.

Key legal requirements

The construction regulations have multiple sections that prescribe requirements for placement and storage of material, allowable load limits, stability, and the prevention of movement, which includes ensuring that:

  • every part of a project is designed and constructed to support or resist all loads and forces likely to be applied to it
  • every part of a project be adequately braced to prevent any movement that may affect the stability or cause its failure or collapse
  • waste material and debris is removed to a disposal area as often as is necessary to prevent a hazardous condition from arising
  • material and equipment are stored and moved in a manner that does not endanger a worker
  • material and equipment are piled and stored in a manner that prevents it from tipping, collapsing or rolling
  • a level area extending at least one metre from the upper edge of each wall is kept clear of equipment, excavated soil, rock and material
  • the stability of the wall is maintained

Precautions to consider

  • Identify all actual and potential hazards related to the placement of materials or spoils.
  • Understand the load capacities of the lay-down area where materials and spoils will be placed.
  • Determine the weight, stability, composition, configuration and potential for movement of the materials or spoils.
  • Establish control measures to protect against the hazards.
  • Allocate necessary resources to implement all control measures.
  • Recognize how conditions may change or compound upon one another.
  • Have a change-management plan for when conditions change, which includes a re-assessment of actual and potential hazards.

Reassess when conditions may have changed

A significant part of re-assessing when conditions have or are likely to change is to recognize when the control measures in place do not have the capacity to protect against the newly introduced hazard or changing condition, and the need to stop the work immediately.

Although space may be limited or the lay-out of the project may restrict options for where materials or spoils can be placed, it is essential to ensure that the chosen area is capable to:

  • withstand all loads likely to be applied
  • materials or spoils are prevented from movement
  • the composition of the spoils will not change
  • workers will not be exposed to any hazards created by the storing and placement of materials or spoils

Contact us

For more information about safety requirements, contact the Ministry of Labour, Immigration, Training and Skills Development Health & Safety Contact Centre: