There's a saying ‘out of sight, out of mind’, but failure to keep underground services in mind when carrying our construction work, particularly when that work involves digging, can be fatal. You may not be able to see underground services, but they should always be considered as a hazard when excavating or going underground.
Contact with underground services can be deadly, and expensive. Unintentional disturbance of live underground cables or pipes can lead to electrocution, fires, electrical ark, gas release, explosions, contamination and flooding. None of which are good news, for your team or your project.
Whether tools or machines are used to excavate ground, cables and pipes can easily be cut with sharp tools or crushed with heavy machinery, causing serious damage to services below ground.
Buried services are a major construction site hazard, particularly in excavation work. There is often uncertainty regarding the location of underground services, as they may have been in place for many years. Even when records do show locations of underground services, these can have inaccuracies.
If you have read our blog post on finding underground services, you will have a good idea of how to locate services on your sites. But what should you do if services are present? Controlling the risks involves keeping services protected, and your team safe.
Many health and safety hazards can be eliminated during the planning and design process, and the same is true when dealing with underground services. Planning your project with underground services in mind can prevent or greatly reduce the risk of problems during the project.
If you can eliminate the hazard by preventing the need to work near underground services entirely, you can remove the risk. When planning your project, the positioning of foundations and other structural elements can be designed to avoid any underground services already present. Or, existing services can be repositioned before works start.
Where you can't completely move services out of the way, it may also be possible to isolate the services during work to minimise the risk should accidental disturbance happen.
During planning, you should also consider how risks will be managed, for example, permits to dig and control measures to protect underground services.
The following precautions can help you to avoid danger from underground services before and during excavation work.
Visit the site and visually check the site for obvious signs of services include patching of road surfaces, valve covers and manholes. These are all indications of what lies beneath.
Find out more in Finding Underground Services (Colours And Identification)
Get plans from utility providers to see what services are likely to be present. Plans from utility or service providers will help to establish if there are underground services within the work area and give an indication of the location of services. Service plans should be available on-site and used to help locate underground services. However, remember that service plans may not be 100% accurate.
Plans are not always accurate in giving the exact position of services and therefore cable and pipe locating devices should be used to develop accurate site service and plans and to mark services on site. Cable locators should be used to trace services and get an accurate picture of where services are laid under the site. The locator eg. CAT scan is used to trace the line of any live pipe or cable and to confirm the location and depth.
Once identified ground marking should be used to mark up the services that have been identified on-site. This allows the workforce to easily located the position of services, and to take precautions when working nearby.
Unless confirmed otherwise, always assume services are live. It is better to assume a cable is live and play it safe than to assume it is dead and potentially put your life and the lives of others at risk.
Trial holes using hand tools should be dug to confirm the location of buried services. A series of trial holes will confirm the exact position and depth of underground pipes and cables.
Any digging carried out close to services must be safe. Where there is a reason to believe there may be underground services present, hand digging with insulated tools should be used. Always use insulated tools. Power tools or machinery should not be used within 0.5m of pipes or cables. Excavating alongside the services and then digging horizontally to expose them is best practice as it greatly reduces the risk of damage through downwards pressure.
Your choice of tool can reduce the risk to yourself and minimise the risk of damage to installed services. Spades and shovels are less likely to pierce cables than picks, forks or other sharp tools.
Once exposed, services may need additional support providing, as they are no longer supported by the ground. Services may also need extra protection if their location means they are at risk of damage. Never use exposed services as hand or footholds.
Excavation work is a high-risk activity needs to be planned, managed and monitored on-site to be carried out safely. Download the excavation permit to work and control the excavation risks on your sites. Raise awareness of the risks with the underground services toolbox talk, and make sure your team know how to dig safely.