Working in construction can be rewarding both financially and in terms of job satisfaction. If you are a true artesian contractor who takes pride in his work and treats clients with respect and honesty you will have a successful business.
Construction can also be quite challenging. It requires leadership, communication, and problem solving skills. Nowhere is this more true that when attempting to minimize risk on the job.
One phase of construction that has its’ own elevated risk profile is excavation. Excavation typically refers to the movement of dirt and/or rock on a construction site. Modern excavators have such expanded tool attachments that the profession can find itself called upon to do much more than the traditional dirt moving jobs of the not too distant past.
Regardless of these new modes of operation, the risk profile for excavators has remained remarkably consistent throughout the years.
What Risks do Excavators Encounter?
Excavators come in all shapes and sizes but they are all relatively large, heavy pieces of equipment that do large amounts of difficult work in a fraction of the time it could be done by hand. Because of their size, weight, noise and the often limited visibility of the operator, excavation is risky business.
Here is a sampling of the more traditional risks associated with the trade.
- Underground essential services – including gas, water, sewerage, telecommunications, electricity, chemicals and fuel or refrigerant in pipes or lines. Information about the location of these and other underground services, such as drainage pipes, soak wells and storage tanks, in and adjacent to the workplace, should be established before directing or allowing excavation work to commence
- The fall or dislodgement of earth or rock
- Falls from one level to another
- Falling objects
- Inappropriate placement of excavated materials, plant or other loads
- The instability of any adjoining structure caused by the excavation
- Any previous disturbance of the ground including previous excavation
- The instability of the excavation due to persons or plant working adjacent to the excavation
- The presence of or possible inrush of water or other liquid
- Hazardous manual tasks
- Hazardous chemicals (e.g. These may be present in the soil where excavation work is to be carried out)
- Hazardous atmosphere in an excavation (e.g. Using Methyl Ethyl Ketone (MEK) solvent for PVC pipes in poorly ventilated trenches)
- Vibration and hazardous noise
- Overhead essential services (power lines) and ground mounted essential services (transformers, gas and water meters).
What is Pedestrian Accident?
That is a pretty impressive list of risks for one construction speciality. However you may have noticed that absent on this list is the leading cause of death and disability in excavation operations, which are pedestrian accidents. Now, pedestrian accidents are not those that involve people walking down the street, they involve any person walking or working at the job site.
These often occur when the job site isn’t well managed and there are a variety of trades working in close proximity to one another. Without a spotter and some basic pedestrian controls on the job, mistakes can turn deadly in hurry.
What Should You Consider When assessing Excavation Risks?
So once common risks have been identified, it can be relatively straightforward to put together a plan for avoiding them the future.
When assessing the risks associated with excavation work you should consider things such as:
- Local site conditions, including access, ground slope, adjacent buildings and structures, water courses (including underground) and trees
- Depth of the excavation
- Soil properties, including variable soil types, stability, shear strength, cohesion, presence of ground water, effect of exposure to the elements
- Fractures or faults in rocks, including joints, bedding planes, dip and strike directions and angles, clay seams
- Any specialized plant or work methods required (e.g. Ground support)
- The method(s) of transport, haul routes and disposal
- What exposures might occur, such as to noise, ultra violet rays or hazardous chemicals
- The number of people involved
- The possibility of unauthorized access to the work area
- Local weather conditions
- The length of time that the excavation will be open.
What Can You do to Lower the Risk on Excavations
Some control measures are more effective than others. Control measures can be ranked from the highest level of protection and reliability to the lowest. This ranking is known as the hierarchy of control.
You should always aim to eliminate a hazard, which is the most effective control. If this is not reasonably practicable, you should minimise the risk by one or a combination of the following:
- Substitution – for example, using an excavator with a rock breaker rather than manual method
- Isolation – for example, using concrete barriers to separate pedestrians and powered mobile plant to reduce the risk of collision
- Engineering Controls – for example benching, battering or shoring the sides of the excavation to reduce the risk of ground collapse.
If risk remains, it should be minimised by implementing administrative controls, so far as is reasonably practicable, for example by installing warning signs near the excavation.
Any remaining risk should be minimised with suitable personal protective equipment (PPE), such as providing workers with hard hats, hearing protectors and high visibility vests.
Administrative control measures and PPE rely on human behaviour and supervision and used on their own tend to be the least effective in minimising risks.
Factors that should be considered when choosing suitable control measures include:
- Excavating plant – when quantities are large, it may be effective to use different types of plant for the various materials to be excavated
- Stockpiling arrangements – another site may need to be found for temporary stockpiling of materials
- Material placement – the methods and plant used for excavating, transporting and compacting the material should be evaluated
- Dewatering equipment, if required, and the system to be used
- Transport of the excavated material – the type of plant used, the length of haul, the nature of the haul route, and the conditions of tipping and/or spreading.
In the end, the complete elimination of risk is impossible. For this reason it is essential that the last component of risk management is the elimination of legal liability from you operation and for that there is no substitute for a quality contractors general liability insurance policy designed specifically to protect you