Safety for Sloped and Benched Excavations
The Problem
Cave-ins remain one of the most serious hazards in excavation work, even when trenches are properly sloped or benched. Workers must stay vigilant, follow established safety protocols, and ensure that a Competent Person has verified conditions before entering any excavation. Today, we’ll discuss how to protect yourself and your crew when working in or near sloped or benched excavations.
Identify the Hazards
- Cave-Ins: Excavation walls can fail due to unstable soil, weather, or incorrect sloping or benching.
- Falling Objects: Tools, equipment, or loose soil can fall from above, striking workers below.
- Soil Distress:Cracks, fissures, or bulging walls are signs that a trench wall may collapse.
- Unsafe Access: Climbing on trench walls is dangerous and can lead to falls or trigger wall collapse.
Safety Practices and Preventative Measures
1. Ensure the Excavation is Approved for Entry
- Competent Person Clearance: Do not enter any excavation unless it has been inspected and signed off as safe by a Competent Person.
2. Protect Against Falling Objects
- Maintain Safe Distances: Keep tools, materials, and machinery at least 600 mm away from the edge.
- Secure Items: Use wedges, chocks, or barriers to prevent objects from rolling or sliding into the excavation.
3. Monitor for Soil Distress
Be alert for warning signs:
- Cracks or fissures along trench edges
- Bulging or sloughing soil
- Loose debris falling into the trench
Report immediately to the Competent Person for assessment and corrective action.
4. Safe Entry and Exit
- Do Not Climb Walls: Never climb the sides of a sloped or benched trench.
- Use only ladders, ramps, or other approved means of access.
- For trenches deeper than 1.2 metres, ensure access is provided every 7.5 metres of horizontal travel.
5. Protect Workers Below
- If other workers are in the excavation, install barricades or protective measures to prevent tools, materials, or soil from falling in from above.
Real-Life Case or Scenario
A few years ago, a worker entered a sloped excavation without notifying the Competent Person. Due to soil instability, part of the wall collapsed, burying the worker up to their waist. Co-workers acted quickly to free them, but the incident could have been prevented if the trench had been properly inspected and cleared for entry.
Employee Responsibilities
- Confirm that the Competent Person has approved entry into any trench.
- Follow all safety instructions and use only approved access points.
- Keep materials away from trench edges.
- Stay alert for signs of soil instability and report concerns immediately.
Employer Responsibilities
- Provide training in excavation and trench safety.
- Ensure all excavations are inspected and signed off by a Competent Person.
- Provide compliant access/egress (e.g. ladders, ramps).
- Put measures in place to protect workers from falling objects and soil collapse.
Discussion & Questions
- “What signs of soil instability have you seen in past excavations?”
- “Have you ever encountered or witnessed a trench collapse? What happened and how was it handled?”
Encourage your team to share past experiences or raise any current concerns.
Commitment/Action Plan
Let’s commit to never entering an excavation without a Competent Person’s clearance. Before starting any task in or near a trench, check for safe access, look for signs of instability, and make sure your work area is protected from falling objects
Wrap-Up
Working in sloped or benched excavations comes with real risks, but those risks are manageable with the right planning, precautions, and communication. By following these safety practices and looking out for one another, we can help ensure everyone gets home safely. Safety is always a team effort.
Standards Overview
Under the Health and Safety at Work Act 2015 (HSWA) and WorkSafe NZ excavation safety guidance, employers and PCBUs must:
- Ensure sloped or benched excavations are designed and maintained to prevent collapse.
- Provide safe access/egress for excavations deeper than 1.5 metres.
- Inspect and approve trenches through a Competent Person before workers enter.
- Install controls to protect workers from falling objects and unstable soil.
Disclaimer
These toolbox talks are provided for informational and educational purposes only and are not a substitute for professional legal, health and safety, or regulatory advice.
The content reflects recognised best practices and general industry standards as at the date of publication. However, it may not be applicable to all workplace environments or specific operational contexts.
It is the responsibility of the Person Conducting a Business or Undertaking (PCBU), as well as officers, workers, and other duty holders under the Health and Safety at Work Act 2015 (HSWA), to ensure compliance with all relevant laws, regulations, and WorkSafe New Zealand guidance.
The authors, presenters, and distributors of this toolbox talk disclaim all liability for any loss, damage, or injury arising from the use or reliance on the information provided. Users should seek advice from a suitably qualified health and safety professional or legal advisor for guidance tailored to their specific circumstances.
Always follow your organisation’s policies, procedures, and safe work practices to manage risks and maintain a safe and healthy workplace.
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