Coal Inspectorate | Bulletin | No.210 V 1 | 21 March 2023

Review the silica exposure risk and associated controls when encountering stone

What happened?

Over the past six months, Coal Mine Workers have recorded personal respirable crystalline silica exceedances (11) while conducting stone drivage tasks, and mining through faults and/ or cavities.

How did it happen?

These exceedances have occurred across different underground mines indicating that this isn’t a site-specific issue. The magnitude of some of these exposures has been significant. On three occasions the concentration has been up to five times the shift-adjusted exposure limit. Directives have been issued to mines to review their dust management plans and the effectiveness of existing dust control strategies.

Key issues

The Inspectorate has observed common issues across sites in relation to this rising trend in person respirable crystalline silica exceedances:

• Failure to anticipate the potential increase in silica exposure when mining through changing conditions.
• Failure to identify and understand the change in dust exposure pathways that present when mining through stone.
• Failure to review existing dust control effectiveness with respect to the change in risk profile and to make adjustments prior to the change.

Recommendations

All Site Senior Executives should:

• Review the current dust Trigger Action Response Plans and ensure there are mechanisms in place that trigger review of dust controls when mining through stone, faulted ground and/or cavities.
• Ensure dust controls are appropriate for the change in risk profile.
• Ensure the Safety Mangement System, with respect to dust management, considers the requirements of Recognised Standard 15 'Underground respirable dust control'.
• Consider the use of real time monitoring to understand dust exposure sources, pathways and the effectiveness of dust controls.
• Ensure the investigation process for reviewing exceedances aligns with the requirements specified in Recognised Standard 14 'Investigation exposure exceedances", paying particular attention to identifying causal factors and reviewing the performance of existing dust controls.

References and further information

• Recognised Standard 14: Monitoring respirable dust in coal mines.
• Recognised Standard 15: Underground respirable dust control.