Excavation Safety and the Role of the Competent Person
The Problem
Excavation work is essential in construction, but it comes with serious risks. Ground collapses, hazardous atmospheres, and utility strikes can lead to severe injury or death. Statistics show that trench collapses are one of the most life-threatening hazards on a construction site. This is where the role of the Competent Person is critical—assessing site conditions, ensuring protective systems are in place, and helping keep everyone safe. Today, we’ll talk about common excavation hazards, the responsibilities of the Competent Person, and how everyone on-site plays a part in excavation safety.
Identify the Hazards
- Ground Collapse: The most dangerous excavation risk, often fatal if support systems are missing or fail.
- Hazardous Atmospheres: Excavations can contain toxic gases, fumes, or low oxygen levels, particularly in confined spaces.
- Underground Services: Striking electrical cables, gas pipes, or water mains can cause electrocution, gas leaks, or flooding.
- Unexpected Events: Rain, broken water lines, or nearby equipment movement can destabilise the ground, increasing risks.
Safety Practices and Preventative Measures
Soil and Site Assessment
- Carry out daily inspections of soil condition and nearby risks to determine the right protective measures—such as benching, battering, or shoring.
Protective Systems
- Ensure protective systems are installed correctly and are robust enough to prevent ground collapse. These systems must be maintained throughout the excavation process.
Inspections and Hazard Control
- Inspect the excavation daily, and after any event that could affect its stability (e.g. heavy rain or leaks).
- Test for hazardous atmospheres and use ventilation where necessary to ensure a safe environment.
Authority to Stop Work
- The Competent Person has the authority to stop work and remove workers from the excavation if unsafe conditions are identified.
Responsibilities for All Workers
- Report Hazards: Immediately report loose shoring, water buildup, or damage to support systems.
- Follow Safety Procedures: Always wear the correct PPE, stay out of restricted areas, and remain alert to changes in the work area.
Real-Life Case or Scenario
A construction crew began excavation without proper trench protection. The ground gave way unexpectedly, and part of the trench collapsed—resulting in a fatality. The Competent Person was not actively monitoring the site that day. If inspections and appropriate ground support had been in place, this tragic incident could have been avoided.
Employee Responsibilities
- Carry out pre-start checks and follow all trench protection procedures.
- Report unsafe conditions to the Competent Person without delay.
- Stay out of unsupported trenches and follow access restrictions.
Employer Responsibilities
- Appoint a trained Competent Person for all excavation work.
- Provide trench protection systems, gas detectors (where needed), and suitable PPE.
- Deliver excavation safety training to ensure workers understand and can respond to site hazards.
Discussion & Questions
- "What are some warning signs of an unsafe trench or excavation?"
- "Have you experienced an excavation hazard on-site? What happened and how was it resolved?"
- "What can you do to support the Competent Person’s role in excavation safety?"
Encourage workers to share their experiences and questions.
Commitment/Action Plan
Let’s commit to supporting our Competent Person and staying vigilant in all excavation work. Before we start today, we’ll review our trenches and trench protection. If anything looks unsafe, speak up—your safety depends on it.
Wrap-Up
Excavation work is high-risk, but with strong planning, regular checks, and teamwork, we can avoid serious incidents. Thanks for your time today—let’s prioritise safety and look out for one another.
Standards Overview
Under the Health and Safety at Work Act 2015 and WorkSafe NZ guidelines:
- A Competent Person must oversee excavation safety, including site assessments and hazard controls.
- Trench protection (benching, battering, shoring) is required for excavations deeper than 1.5 metres, or where there’s a risk of collapse.
- All workers must be trained to recognise hazards and respond appropriately.
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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