An inspection of confined space practices at NSW coal mines has revealed a range of safety issues associated with the management of confined space programs and equipment at mine sites.
One important issue has been the resetting of alarm point thresholds, whereby the portable gas detector would fail to warn workers to exit the space due to explosive or toxic atmospheres.
Workers at mining sites across Australia normally place confidence in the effectiveness of the portable gas detectors to warn them of hazardous atmospheres that, in some cases, could result in a fire, explosion or asphyxiation.
The NSW Resources Regulator has issued a safety bulletin in relation to issues identified.
The bulletin highlighted that during routine inspections of principal hazards across NSW mine sites, Inspectors identified a large range of issues including:
- risks not being adequately identified during the risk assessment process, and consideration not being given to all flammable or toxic gases that may be present in confined spaces
- gas detectors not being introduced to site through standard processes and change management. At some sites the statutory electrical engineer did not review the equipment’s explosion protection certification or verified the equipment was fit for purpose
- contractors undertaking confined space work using their own gas detectors but this equipment not always going through a full introduction to site process, such as certification review, calibration checks and alarm set points checks and confirmation as being consistent with site permit and plans
- detectors found to have alarms set to different values to those identified in the confined spaces permit and management plan. In some cases, the second alarm setpoints were set way too high, i.e. 200 PPM carbon monoxide.
In some cases, the second alarm setpoints were set way too high, i.e. 200 PPM carbon monoxide
- some mines mandating operating in percentages of the lower explosive limit (LEL), consistent with the Work Health and Safety Regulation 2017, some mines calibrating their monitors in percentages of the volume of methane, while others are relying on underground coal alarm limits
- management and workers being unfamiliar with the equipment and unable to adequately demonstrate alarm setpoints and bump test or challenge test the equipment
- several sites having no facilities for bump tests/challenge tests of confined space gas detectors (manufacturer requirements and AS/NZS 2290.3:2018)
- calibrations of some equipment by NATA-accredited laboratories not being undertaken at appropriate frequencies
- some confined space management systems not distinguishing between ‘continuous’ and ‘regular’ monitoring even though the Work Health and Safety Regulation 2017 requires continuous monitoring where flammable gas levels are equal to or greater than 5% but less than 10% of the lower explosive limit for the gas.
The Resources Regulator has recommended that mine operators ensure:
- the correct selection of gas detection equipment that matches confined space environment hazards identified through a risk assessment, so they can detect and alarm all relevant flammable and toxic gasses that may be present
- all gas detectors used in confined spaces on the surface of a mine are appropriately certified and meet the requirements of the electrical engineering control plan, including having been through an ‘introduction to site process’ and sign off by the mine statutory electrical engineer
- mine sites maintain gas detectors in accordance with manufacturer’s recommendations and AS/NZS 2290.3:2018
- gas detectors are bump/challenge tested every time before use to ensure correct readings of gasses and operation of alarms
- gas detector alarms are set up as per the confined spaces management plan, permit and any specific confined space entry risk assessment
- where confined space plans and permits reference LEL, detectors are configured in percentages of the LEL and not percentages of the volume of methane (100% LEL is 5% volume of methane and therefore 10% LEL is 0.5% volume of methane)
- personnel working in confined spaces are trained and assessed as competent in the use of gas detection equipment and the management systems (including permits and procedures) used for confined spaces entry at each mine where they undertake confined space work activities
- terminology used in management plans and site permits should be well defined in plans and permits and not left to the workers to interpret.
AMSJ would encourage site staff to share this information across their sites and double check the effectiveness of their gas detection program.
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