The Importance of Performing a Risk Assessment Before Excavating

There’s no denying that excavating comes with a unique set of risks that need to be properly managed to avoid potential incidents. But luckily there are precautions you can take ahead of time to help you identify and manage risks, like carrying out a thorough risk assessment. 

So, before you get started on your next excavation project, we’ve pulled together this guide to help you understand the benefits of performing a risk assessment and how to actually go about carrying out a risk assessment of your own.

Who’s responsible for completing an excavation risk assessment?

Before we get stuck into the nitty-gritty details of what to cover in your risk assessment, it’s well worth familiarising yourself with who’s actually responsible for carrying out a risk assessment before an excavation project. 

According to the Model Work Health and Safety Act, everyone on an excavation site has WHS duties. However, you have specific duties if you’re:

• A person conducting a business or undertaking (PCBU), 
• A principal contractor,
• A designer, manufacturer, importer, supplier and installer of plant, substances or structures, or  
• An officer. 

When it comes to performing a risk assessment, a PCBU is responsible for managing the risks to health and safety that come with excavation work. As part of this, a PCBU must also consult with workers carrying out the excavation project throughout all stages of the risk management process. 

Why is a risk assessment important?

Excavation work comes with a number of different risks from falls and cave-ins to exposure to hazardous materials. These risks could lead to illness or injury if not properly managed, but carrying out a risk assessment helps to identify any potential risks so you can put control measures in place to reduce the chance of any workplace incidents occurring.

Risk assessments are crucial before undertaking an excavation project due to the following reasons:

Safety of workers

Excavation work involves potential hazards such as collapsing soil, cave-ins, contact with underground utilities, falling objects and equipment-related incidents. Conducting a risk assessment helps identify these excavation hazards and implement appropriate control measures to protect workers involved in the project.

Injury prevention

By identifying and assessing potential risks, a risk assessment enables the implementation of measures to prevent injuries. This may include using Personal Protective Equipment (PPE), implementing safe work practices, establishing clear protocols for communication and coordination and providing adequate training to workers.

Protection of surrounding structures and utilities

Excavation work can pose risks to nearby structures, underground utilities (such as gas lines, electrical cables or water pipes) and the overall stability of the area. Conducting a risk assessment helps identify potential risks that could lead to damage and enables the implementation of preventive measures to mitigate those risks.

Compliance with WHS duties

Under the model WHS Act, there are specific duties that apply to excavation work that relate to managing the risks of excavation, falls from heights and noise. By conducting a risk assessment, you’re able to ensure compliance with these requirements, reducing legal liabilities and potential penalties.

Cost and time efficiency

Identifying potential risks and implementing appropriate control measures before starting an excavation project can help prevent accidents, delays and costly damage. By addressing risks proactively, the project can proceed more smoothly, minimising downtime and avoiding costly repairs or rework.

Stakeholder communication

A risk assessment provides a structured way to communicate potential hazards and their associated mitigation strategies to all relevant stakeholders, including workers, supervisors, clients and regulatory authorities. Clear communication enhances understanding, collaboration and accountability among all parties involved.

Ultimately, risk assessments help you to keep your workers and equipment safe while also safeguarding your reputation.

The risk assessment process

The Safe Work Australia Excavation Work Code of Practice details the risk management process that should be followed before starting excavation and throughout the course of the project. 

Step 1: Identify the hazards

The first step in the risk management process is to identify all potential risks and hazards relating to the excavation project. Some of the most common hazards that can impact an excavation site include: 

• Falls from one level to another, 
• Falling or dislodging earth or rock, 
• Vibration and hazardous noise, and 
• Exposure to airborne contaminants. 

Step 2: Assess the risks

Once you’ve identified the potential risks that could impact your excavation project, it’s time to assess the risks. While a risk assessment isn’t mandatory under WHS Regulations, it is required under special circumstances, like when you’re dealing with asbestos. With that said, performing a risk assessment helps you to decide on which control measures are needed to help manage the risks and hazards you’ve identified. A risk assessment will also help you to:

• Identify at-risk workers,
• Determine sources and processes of risk,
• Implement appropriate control measures, and
• Evaluate the effectiveness of existing controls.

There are a number of different factors to consider when assessing the risks associated with excavation work, including:

• Local site conditions, like the ease of access, adjacent structures and trees,
• Excavation depth,
• Soil properties, rock fractures and faults,
• Specialised equipment or work method requirements,
• Local weather conditions, and
• The duration of excavation work.

Some excavation work is deemed high-risk construction work if:

• It’s in or near a shaft or trench that is 1.5 metres deep or a tunnel, 
• There’s a risk of a person falling more than 2 metres, or 
• There’s a risk of mobile-powered plant colliding with pedestrians or other powered mobile plant. 

In any of these instances, you’ll need to complete a Safe Work Method Statement before the excavation work begins. 

Step 3: Manage the risks

Once you’ve completed a risk assessment and identified the hazards that could impact your excavation site, you must implement control measures to minimise the risks. The ultimate aim is to eliminate the risk altogether, but if this isn’t reasonably practicable then you might need to use a combination of the following control methods:

• Substitution: For example, using machinery, like an excavator, in place of manual processes.
• Isolation: For example, using barriers to separate pedestrians from the excavation site. 
• Engineering controls: For example, reinforcing the sides of your excavation using methods, like benching, battering or shoring, to reduce the risk of ground collapse or cave-ins.

If any risks still exist once these control measures have been implemented, you should seek to further mitigate them by implementing administrative controls, like installing warning signs near the excavation site. Any remaining risk should then be minimised with suitable PPE, like hard hats, high visibility clothing and hearing protection. Because both administrative controls and PPE rely on human behaviour, they’re considered the least effective methods for minimising risk and should only be used as a last resort. 

Step 4: Review control measures

Once you’ve implemented the relevant controls at your excavation site, it’s important to regularly review them to ensure they’re effective in protecting the health and safety of those on-site. 

Reviewing your control measures is a dynamic process, so they should be revised when:

• The control measure isn’t effective in controlling the risk,
• Before implementing a workplace change that is expected to introduce new or different health and safety risks that the existing control measures may not adequately address,
• A new hazard or risk is identified within the workplace,
• Consultation with stakeholders reveals the need for a review, or 
• In response to a request from a health and safety representative.

For more information on the risk management process for excavation work, refer to the Excavation Work Code of Practice.