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It’s never good to find out the hard way that there was a gas, power, water or communications line buried right where you needed to put something on your site! Safe excavation practices help you to get through the work without injury and avoid hitting critical services. 

Digging blind is not the best way forward for your schedule or your safety, so we have put together some key notes for you to bear in mind when excavating to help save you some costs, time and help you to avoid tragedy. 

What is the definition of excavation?

Excavation work is referred to as any work involving the removal of soil or rock from a site to form an open face, hole or cavity, using tools, machinery or explosives. This includes open excavations, potholing, pit excavations, trenches, retaining walls and shafts and drives.

What are my legal obligations? 

Employers have a legal duty of care to take reasonable actions to protect both the people and the services which may be affected by their work. Getting and using the appropriate information on the services is an important part of ensuring safe excavation on your site. There is a large range of options this can cover, so we will cover the basics in this article.
If you have more complex excavations and want advice then get in contact with us.

Remember any ground disturbance regardless of depth can damage infrastructure networks like gas, water, electricity so you need to get the right information to keep you & the utilities safe.

Where do I start to prevent incidents on-site, protect workers and prevent asset damage?

First, you need to get information on what the assets in the area may be. You can often get this information from BeforeUdig. This online system is the easiest way to request known plans from the asset owners. It is important to know that not all Asset Owners are members of BeforeUdig, so it cannot show you everything that is in the area of your excavation. You may need to contact any other asset owners directly to get hold of plans, drawings and information regarding their assets known positions prior to starting your work.

Wait to receive all information on the assets before commencing work, and only refer to plans that are current. 

Once you have information on the assets, make sure the plans are with the workers on-site and that they have appropriate health and safety information and instruction. You should also isolate work around the underground assets from the public.

Pay attention to the clues around your site such as marker posts, inspection points and metres. Never assume pipes and cables run underground in a straight line or are at their correctly specified depth, and always assume all lines are live, even if they look as though they are abandoned or decommissioned. 

Remember all digging activities can damage underground infrastructure. You should conduct a risk assessment for the task so that you can identify the hazards to focus on, and put in place suitable controls. Workers involved in the excavation need to be trained and competent to do their part of the work e.g the Excavator operator is appropriately licensed. 

Quick tips: The 5 P’s for safe excavation

To minimise the risk of damage and potential loss of life, it’s best practice to follow the 5 P’s for safe excavation:

• Plan – Plan ahead by lodging your BeforeUDig enquiry at least two business days before your project begins, and make sure you have the correct information required to not just carry out the work but how to respond to any possible emergencies.
• Prepare – Prepare by reviewing the utility plans and contacting the asset owners if you need assistance. Look for onsite utilities clues such as pit lids, marker posts and metres. If you need further verification you could have Ground Penetrating Radar (GPR) carried out to show exactly where buried things are. 
• Pothole – To confirm the exact location of the underground infrastructure(s), pothole if permitted using the asset owner’s stated method as specified on the asset owner’s plan and information pack. Work slowly on this as you’re actually trying to “hit” it but without damaging it.
• Protect – If potholing has occurred, protect the infrastructure by using various methods; such as communicating to all working on site, erecting barriers and marking the location of the exposed infrastructure. 
• Proceed – You should only proceed with your excavation work after you have planned, potholed (unless prohibited) and have your necessary protective measures in place.

Remember to stay vigilant and watch for changes in the ground/soil as you dig.

Need Help? 

If you’ve got a question about safe excavation or any other health and safety matter, the HazardCo Advisory Team is here to help. Give them a call on 0800 555 339. 

Need more information?

The BeforeUDig NZ website has a tonne of resources available. Worksafe NZ also has a Best practice guide.