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Coal Inspectorate | Bulletin | No.204 V 1 | 05 August 2022

Spontaneous combustion monitoring and response systems

What happened?

Recent analysis into technical reports and audit results has highlighted concerns about how underground coal mines are interpreting guidance to develop their spontaneous combustion Triggered Action Response Plans (TARPs).

Spontaneous combustion events have previously occurred in bord, pillar and longwall mines – some with devastating consequences. The most recent events in 2020 resulted in serious injury to coal mine workers, two gas explosions, and previous events have also resulted in sealing mine workings.

How did it happen?

Investigations into past events have shown that TARPS have been found to be inadequate or applied incorrectly.

Key issues

Recommendations

Site Senior Executives (SSEs) should direct that the site TARPs are reviewed and endorsed by a suitably qualified expert on a regular basis - ideally annually.

Underground Mine Managers (UMMs) should review and update their spontaneous combustion TARPs against the monitoring and response system metrics below and have the TARP endorsed by a suitably qualified expert.

Reviewing the effectiveness of monitoring and response systems

The metrics in your spontaneous combustion TARP need to be representative of the environmental conditions being monitored to ensure they detect changes in this hazard, and trigger an early response to indicators of a spontaneous combustion event.

Escalation of any of these key gas metrics should be thoroughly tested to ensure that they accurately interpret the atmospheric changes being monitored and measured.

A list of criteria to be considered when developing your spontaneous combustion Principal Hazard Management Plan (PHMP) and TARPs has been developed following analysis of historical events. These key matters should be considered and documented.

  1. Review development of your TARPs
  2. Assess the spontaneous combustion propensity of your coal seam
  3. Considered the relativity of gas evolution data when developing trigger metrics
  4. Review historical data from any incidents at operations conducted in the same seam
  5. Assess plans in relation to historical incidents which have not effectively provided appropriate responses to manage the events
  6. Consider the effective application of your trigger metrics where more than one spontaneous combustion indicator may be present
  7. Appraise the relevance of gas monitoring data in your assessment of the potential escalating spontaneous combustion event and consider:
  8. Consider gas data obtained from goaf wells and the correlation of these indicators with the underground gas monitoring data
  9. Consider the application of Grahams Ratio to gas monitoring locations that have the potential for oxygen deficiency where there is an absence of ventilation currents
  10. Consider the impacts of nitrogen inertisation to your gas monitoring locations and the potential for the 'masking' of key indicators
  11. Consider the validity of CO/CO2 ratio triggers in your TARPs to consider:
  12. Considered the presence of Ethylene in your TARP trigger metrics to determine:

Authorised by Peter Newman - Chief Inspector – Coal

Contact: Shaun Dobson, Deputy Chief Inspector of Coal Mines , 0407 011 214

Issued by Resources Safety & Health Queensland

Safety: This information is issued to promote safety through experience. It is not to be taken as a statement of law and must not be construed to waive or modify any legal obligation.
Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy, understand the content, findings and recommendations as applicable to their operation. SSEs should validate that recommendations have been implemented.

All information on this page (Spontaneous combustion monitoring and response systems - https://www.rshq.qld.gov.au/safety-notices/mines/spontaneous-combustion-monitoring-and-response-systems) is correct as of time of printing (12 Aug 2022 3:05 am).