Different types of excavations and managing the risks
What is excavation work?
Moving or removing earth or other materials with tools or equipment is generally classed as excavation work. Excavations are used in a number of different situations, such as during the construction of buildings, building retaining walls, and installing underground utilities. It is important that when carrying out excavations that underground utilities are always identified first.
Some common types of excavations used in residential construction are cut and fill excavating, pile holes, potholing, and trench excavation:
Cut & Fill
Cut and fill excavation, also known as stripping excavation is the method used to clear and prepare large areas. This method involves removing all of the material such as rock, sand, and topsoil that would be unstable to work on.
Pile holes are usually excavated using methods including backhoe digger, drilling or hydro excavation. Pile holes should be covered and barricaded as soon as possible and only those involved in the works allowed nearby. Water buildup should be monitored and pumped out.
Potholing is simply a small excavation or hole to inspect and find underground services. It’s important that potholes are covered or barricaded when they are not being used to prevent anyone from being hurt.
Trenching is an excavation method used to prepare or replace underground utilities, build retaining walls, or investigate what is beneath the surface.
Trenches are long narrow excavations, and are deeper than they are wide. Conducting trench excavation is subject to many different factors including its size, the likelihood of underground utilities, and materials. This means that the most effective method of excavation changes from project to project, and should always be treated with caution.
Due to the scale of some of these operations, it is common that they usually require large excavation vehicles and good controls around traffic management should be in place.
Managing the risk
No matter how deep the excavation is, if there is a risk of collapse, you need to carry out a Risk Assessment and put controls in place to prevent this, you can find our Task Analysis on excavation work in your Hub. Excavations work is classed as high risk, so it is important that if you are completing excavations, that you are familiar with the guidance in the WorkSafe Good Practice Guidelines for Excavations Safety.
Covering or bridging.
When covering holes or bridging shallow trenches on building sites, ensure that the material used to cover or bridge is made from a suitable material. Heavy-duty plywood designed for weight-bearing, steel plates, or other products specifically designed for that purpose.
For holes, ensure they are fully covered and the covering cannot easily move. Avoid slip and trip hazards by ensuring walkways around these hazards are managed.
Water hazards after rain can create a drowning risk, especially for children. It can also increase the risk of sidewall collapse.
Types of barriers
A secure site is very important with any open excavation. You need to consider how long the excavations will stay exposed, and if an excavation is to be left unattended overnight, then consider plating, fully enclosing with a safety fence, or backfilling to minimise the risks. Barricades, cones, plastic mesh netting not supported by a solid frame, and hurdles are not sufficient to adequately protect from excavation risks. We recommend safety fences for internal fencing for long-term or unattended worksites where excavation hazards are present
Understand your competency level
Excavations up to 1.5m deep, you should have recent experience in carrying out or supervising excavation work.
1.5m – 3m deep you should have recent experience in carrying out or supervising excavation work at these depths, technical or trade qualification (eg a civil engineer or drain layer)
3-6m Technical or trade qualification (eg a civil engineer or drain layer). Experienced temporary works designer able to judge whether it is safe.
Make sure you are aware of your requirements for managing the risks of excavation.
The HazardCo App site review resource has a list of risk controls that should be in place to minimise the risk associated with excavation work.
If you need a hand getting started or would like more information, get in touch with the friendly HazardCo team today – we’re always happy to help.