Screening plant side conveyor fails suddenly

Background

On 4 August 2022, a side discharge conveyor on a screening plant at a quarry collapsed suddenly while operating. The supporting structure failed at the midpoint, instantly causing the discharge end of the conveyor to collapse.

A steel diversion chute had been retro-fitted to the discharge end of the conveyor several months before the incident. Clay material had also built up inside the chute. The extra weight of the steel chute and built up material caused the failure.

The steel diversion chute was not supplied, installed or checked by the manufacturer of the plant.

No employees were injured in the incident.

Recommended ways to control risks

To reduce the risk of plant structural failure, quarry and mine operators should:

• conduct risk assessments during the commissioning of plant (ie. before first use) and after any modification to plant to identify all potential hazards and assess the adequacy of control measures
• implement a change management process to help identify introduced hazards and their risks
• engage experts and consult personnel when assessing risk or developing risk assessment teams to ensure all aspects of risk are considered. For matters of plant structural integrity, you should always engage qualified and certified engineers
• ensure employees are trained to identify hazards and assess risk, including regular retraining
• ensure employees are trained in the measures used for managing and controlling risk (eg. isolation procedures and related barrier controls used to prevent employee access)
• engage Original Equipment Manufacturers before planning for or making any plant modifications

Legal duties

Employers have duties under the Occupational Health and Safety Act 2004. They must, so far as is reasonably practicable:

• provide and maintain a working environment that is safe and without risks to the health of employees and independent contractors
• provide and maintain plant or systems of work that are safe and without risks to health
• provide employees with the necessary information, instruction, training or supervision to enable them to do their work in a way that is safe and without risks to health
• ensure that persons other than employees are not exposed to risks to their health or safety arising from the employer’s conduct
• consult with employees and health and safety representatives when identifying or assessing hazards or risks and making decisions about risk control measures

Under the Occupational Health and Safety Regulations 2017 employers must, so far as reasonably practicable, eliminate the risk associated with plant, including plant modifications.

In addition, mine operators must:

• identify all mining hazards at their mine and assess the related risks, so far as is reasonably practicable
• implement risk controls that eliminate or reduce risks, so far as is reasonably practicable
• establish and implement a safety management system for the mine (if the mine is a prescribed mine), which provides a comprehensive and integrated management system for all risk control measures