Nobody wants a mobile plant to roll over on them, but many factors - heavy rain very much included - can massively increase the risk of an incident involving one of these beasts of the workplace. All mobile plant is susceptible to the ground condition reducing its bearing capacity, but anything relying on outriggers, or any heavy and high plant, is at an increased risk after rainfall. Waterlogged ground can also increase the risk of mobile plant rollovers.
In December 2021, a concreter suffered serious injuries including a cervical spinal fracture and lacerations to his head and body after being struck by a mobile concrete placing boom at a residential construction site. The concreter was part of a team pouring a house slab.
Early investigations indicate one of the mobile concrete pump’s outriggers moved off its dunnage while operating, sinking into the adjacent ground. This appears to have resulted in the concrete pump’s boom moving in an uncontrolled manner, striking the concreter.
There were two more incidents in March 2022 where mobile concrete placing booms overturned. Fortunately, there were no injuries but there was significant damage to both buildings and plant.
Types of plant
Common types of plant on worksites include:
- Forklifts and telehandlers
- Cranes (from small ‘Franna’ or pick & carry cranes to big lifting 200T mobile cranes)
- Earthmoving equipment (such as excavators, loaders, backhoes and skid-steer loaders)
- Civil plant (such as scrapers, graders, trenchers and loaders)
- Concrete pumping trucks
- Material delivery vehicles
- Elevated work platforms and scissor-lifts.
Ground Conditions
There are numerous risks associated with the setting-up of mobile plant, such as concrete pumping equipment, including mobile concrete pumping booms tipping over and the risk of workers being crushed or run over by the mobile concrete pump itself.
Ground conditions can vary dramatically from one workplace to another, and even within a site itself over time. Saturated earth will dramatically reduce the bearing capacity of the ground. Failure to address poor ground conditions may cause the plant to overturn and result in serious injury to the concrete pump operator and other people nearby. Factors that affect the ground providing adequate support include:
- water, including when it is mixed with the soil as mud, and where it is present under the surface
- the type of ground (clay, sand, rock or a mixture of these)
- back-filled ground that was previously an excavation or trench
- cavities or penetrations that have been covered but still exist
- continued operation of the concrete pump in one location
- ground slope reduces stability and can also cause the concrete pump to move off supports during use.
Risk Management
Taking steps to manage risks is a condition of doing business in Queensland. Effective risk management starts with a commitment to health and safety from those who manage the business. If an incident occurs, you'll need to show the regulator that you’ve used an effective risk management process. This responsibility is covered by your primary duty of care in the Work Health and Safety Act 2011.
The Work Health and Safety Regulation 2011 includes specific duties for persons conducting a business or undertaking (PCBUs) with management or control of a construction workplace, plant, powered mobile plant and plant that lifts or suspends loads. If you own concrete pumping plant, you are the person with management or control of that plant and have duties to eliminate or minimise the risks associated with the plant.
Set-up
When setting-up a concrete pump, the area should be level, capable of supporting the load and free of obstructions, with careful attention paid to the following:
- precautions should be taken when a concrete pump is used in the vicinity of an excavation, the concrete pump should not be positioned over or adjacent to:
- previously disturbed ground that’s been back-filled
- excavations, trenches or holes in the ground
- cellars, basements or pits
- inadequately compacted or soft ground.
- if the ground is near an excavation, the pump operator should immediately refer the matter to the principal contractor for re-location to a more stable location
- when the concrete pump is continuously operated in one location, ensure the ground has not compacted to the extent that the concrete pump is more likely to overturn
- the pump unit is set up level, and if this is not possible, ensure the incline or angle of the machine does not exceed the manufacturer’s recommendations (refer to operating instruction manual)
- when setting up close to concrete pads/pavement, be aware the ground could be softer due to rain water run-off and/or the ground being disturbed.
Information, training, and PPE
Information, training instruction or supervision for concrete pumping operations should include but not limited to:
- the method for inspection and maintenance of concrete pumping equipment
- knowledge of the manufacturer's operation and service manuals
- the work methods to be used in the setting up and safe operation of concrete placement booms and pumps
- the correct use, care and storage of tools and equipment to be used, including electrical safety practices.
Supervisors must:
- ensure only those workers who have received training and instruction are authorised to carry out that work
- monitor the work sufficiently to make sure safe work practices are being carried out, including the use of all protection systems and personal protection equipment.
The following items of PPE are required when pumping concrete:
The control measures put in place should be reviewed regularly to make sure they work as planned.
