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LEGISLATIVE INTERPRETATIONS

OCCUPATIONAL HEALTH AND SAFETY ACT

Trenching and Excavation over Three Metres Deep

Topic: Trenching and Excavation over Three Metres Deep Issued by: Director, Compliance and Regulatory Review
Statute: Regulation 91-191 Date Issued: October 20, 2016
Section: 49(1)(a)(i) Date Revised:

Question

How does fall protection apply if a trench or excavation is over three metres deep and employees are on the surface?

Answer

In some situations, providing and using fall-protection equipment is required if an excavation or trench is deeper than three metres and there is a risk of falling. If the excavation or trench is properly benched or sloped, the employees near the edge would probably not be exposed to a fall of three metres or more. In this example, fall protection would most likely not be required.

If the trench or excavation is not sloped or benched and trench boxes, shoring or bracing is used, then warning lines, barriers or guardrails are required. However, in some circumstances the added weight of these measures may present the risk of cave-ins. In these cases, providing other types of fall protection is required.

As an alternative to traditional fall-protection methods, a risk assessment would be required. When selecting the control methods, the employer can consider removing or limiting the risk of falling by:


  • Eliminating the risk of employees on the surface falling by barricading access to the trench or excavation.
  • If employees must be on the surface (for example, to supervise employees in the trench or excavation), by having light barriers, such as warning lines, at the edge. (See Note below)
  • Under a competent person’s supervision, and if the soil can sustain the added weight, installing jersey barriers or proper guardrails.
  • Providing an anchor point and travel restraint to employees on the surface.

Whatever method is chosen, it should include a written procedure and training explaining the requirements to affected workers.

Note: Warning lines must be:

  • A minimum diameter of 10mm
  • Suspended at a height between 750mm and 900mm
  • Properly supported to keep the line taut
  • Have visible markers placed every 1.5m along the length of the line

Referenced legislation

49(1) The employer shall provide and the employee shall continually use a fall-protection system when an employee works from

(a) an unguarded work area that is

(i) 3 m or more above water or the nearest permanent safe level,

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