The NSW Mine Safety Investigation Unit has released an investigation report into the death of an underground mine worker at a mine on June 11, 2014.
Read the reports executive summary below. To read the full report, click here.
EXECUTIVE SUMMARY
1.1 Incident overview
About 11.15 pm on 11 June 2014, 26 year-old James Hern drowned when he entered a water filled sump at CSA Mine, Cobar NSW. Mr Hern and a co-worker were attempting to clear a blockage from the 8820 north sump drain hole that had been deliberately clogged in the preceding shifts.
A strainer in the sump hole had also been removed. This strainer can be viewed in figures 10 and 16 of this report. The blockage was preventing the 8820 north sump from draining through to the 8790 north level below. The sump contained a considerable volume of water. The depth at the time of the incident was estimated to be 1.43 metres to the drain hole with a calculated volume of 162,800 litres. It is evident from water markings on the mine wall that the sump was full and overflowing into the adjacent access roadways.
Mr Hern and his co-worker were using an integrated tool carrier (IT) with a work basket attached. It was driven into the sump to the approximate location of the drain hole. Working from the basket, Mr Hern attempted to clear the blockage using a scaling bar with a piece of rope attached.
The intention was to use the scaling bar to pierce the blockage and clear the drain. However during the task the scaling bar was lost in the water. Mr Hern and his co-worker withdrew the IT from the sump and proceeded to the 8790 level below in a light vehicle to determine whether the scaling bar had been successful. There was no water flowing from the drain hole indicating the hole was still blocked.
Both workers then returned to the higher level where Mr Hern removed clothing and walked into the water-filled sump to find the scaling bar and complete the job. A short time later, he disappeared from sight. The co-worker called out, but with no response he contacted the shift supervisor on the radio system who activated the mine’s emergency procedures. Other workers responded to the scene and began search and rescue efforts. Mr Hern was found below the surface with his legs trapped in the drain hole.
Five co-workers entered the water and recovered Mr Hern from the drain hole using the IT and lifting equipment. He was taken by ambulance to Cobar District Hospital but efforts to resuscitate him were unsuccessful and he was pronounced deceased at 12.40 am on 12 June 2014. The post mortem examination determined that the cause of death was consistent with drowning.
1.2 Investigation observations
The investigation has identified a number of system failures relating to the management of risks associated with underground water hazards, the supervision of employees and provision of fit for-purpose equipment for blocking and unblocking sumps.
In this case, there was no risk management plan in place that considered the hazards associated with work on underground sumps and water bodies. There was no safe work procedure documented to undertake such works.
There was no training provided to Mr Hern or his co-worker in relation to the task they were to undertake. There was an over reliance upon Mr Hern and his co-worker to develop their own system of work and assess risks without the relevant information necessary to make such decisions (for example, information about how the drain hole was blocked or alternative methods available to unblock the drain hole). Supervisors and Foremen did not ensure that the task Mr Hern was undertaking was safe and adequately risk assessed.
These failures were exacerbated by the absence of high level risk management controls such as hard barriers (elimination, substitution and engineering controls) to prevent people from exposing themselves to the risk of drowning in an underground sump.
1.3 Foreseeable risk
The risks associated with working in and around water bodies are clearly foreseeable. Mine operators must effectively manage and control these risks to ensure the health and safety of workers. There was a range of water management issues at the mine before the incident that highlight the foreseeable nature of the risks involved in this incident.
These include:
• the regular failure of the pumping system at the 8855 level
• the development of a new mine dewatering program (a change to the management of water at the mine)
• deliberate blocking of the 8820 north drain hole and the adhoc use of inflatable stope bags to block the drain hole
• identification of the 8820 north sump overflowing into adjacent roadways
• attempts to unblock the sump during the day shift before the incident
• identification of safe work methods to remove the water from the sump and unblock it which were not documented or communicated to the service crew
• a history of workers entering sumps to unblock drain holes and undertake sump maintenance at the mine
• the provision of waders to mine workers to undertake work in sumps at the mine.
Accordingly, greater emphasis should have been given to managing the risks associated with the task being undertaken by Mr Hern and the work associated with the mine’s dewatering program using the mine’s risk management system.
1.4 Safety observations
The implementation of the hierarchy of controls is a well-known and legislated tool to control risks to health and safety. The following risk management controls could have been implemented to control the risks to health and safety in relation to the work undertaken by Mr Hern.
Hierarchy of controls
Elimination
Elimination of the hazard is the best hard barrier (control) that can be applied to reduce or eliminate a risk to health and safety. A foreman at CSA mine reported that production could have ceased and the dewatering system turned off to prevent water flowing to the 8820 north sump. This would have eliminated the need to block the sump in the first place, which would have
meant that Mr Hern would never have been required to undertake the task of unblocking the drain hole.
The removal of the water from the 8820 north sump would also have eliminated the risk. It is clear that the submersible pump that was in the 8820 north sump was either not working or ineffective. This is because the pump was plumbed into the dewatering system so water would recirculate. Several supervisors at the CSA mine suggested that an air diaphragm pump could
have been installed so water could be pumped down the decline.
Substitution
By substituting the system of work it is possible to reduce the risk to health and safety and reduce the consequence of risk to health and safety. Many alternate systems of work have been identified that may have reduced the risk to health and safety.
They include:
• unblocking the drain hole earlier in the work program before excessive water accumulated in the sump
• using an air lance or explosive device inserted into the drain hole from the level below which may have unblocked the drain hole and would have negated the need to enter the 8820 north sump either on foot or in the basket of an IT.
Engineering
Engineering controls represent the lowest hard barrier in the hierarchy of controls. Through consultation with a plumbing equipment supply company, investigators identified an engineering solution for deliberately blocking drain holes. The system includes a fit-for-purpose rubber bladder that can be anchored in a drain hole and inflated and deflated remotely, negating the
need to enter a sump in either an IT or on foot to block or unblock a sump drain hole. A picture of the engineering solution is depicted within the report at figure 16.
Another engineering solution identified is appropriate guarding around the drain hole. The strainer that was in the hole before the incident constituted a guard that would have reduced the risk of Mr Hern becoming stuck in the drain hole. Further, a steel mesh grate securely installed over the drain hole would have been an effective hard barrier.
Administrative
Administrative controls are considered soft controls and require a degree of compliance by the workforce, which in turn means that there has to be a higher degree of compliance monitoring by management. They are considered one of the lowest forms of control and should be used in conjunction with hard controls listed above.
The mine’s safety management plan (MSMP) is a legislated overarching administrative control that should minimise risks to health and safety. In this incident it was not applied correctly and failed to reduce the risk to Mr Hern. Risk assessments and safe work procedures should have been created using the MSMP. However, these documents were not created.
The following is a non-exhaustive list of administrative controls that have been suggested to reduce the likelihood of the incident occurring:
• A broad brush risk assessment should have been conducted during the planning phase of the dewatering activities
• The change management system should have been implemented as soon as the change to the dewatering system was identified
• A safe work method should have been created and communicated to Mr Hern before the task was undertaken
• A Job Safety Analysis should have been insisted on by supervisors before work began in the 8820 north sump
• CSAfes should have been completed by every person working in the 8820 north sump (note this included CSAfes by shift supervisors and foremen)
• Adequate work instructions should have been provided to people that were to work in the 8820 north sump in the days before the incident
• Active supervision, including pre-shift inspections of the 8820 north sump should have been undertaken to ensure that the work place was safe for workers
• Specific directives to all workers not to enter sumps and water bodies at CSA mine should have been clearly articulated to all mine workers.
Personal Protective Equipment (PPE)
PPE is the last line of defence and is not an adequate control for hazards on its own. As with administrative controls mentioned above they are classified as soft controls and require compliance by workers to be effective. Mr Hern removed most of his clothing and PPE before entering the sump. However, due to the nature of this incident, it is unlikely that the PPE available to Mr Hern would have prevented this incident from occurring.
The following non-exhaustive list of PPE is suggested to reduce the risk of drowning in and around water bodies at mines:
• Provide personal flotation devices (life jackets) for anyone working near water bodies.
• Position flotation rings at every water body that presents a risk to a worker.
Note the use of waders is not considered appropriate PPE to prevent the risk of drowning.
1.5 Recommendations
This incident highlights the importance of an effective risk management program in relation to works in and around Underground sumps and water bodies. The following recommendations are advanced to improve industry safety and in turn reduce the likelihood of similar incidents reoccurring.
When considering the recommendations below, mine operators are reminded of their obligation to take a combination of measures to minimise the risk, if no single measure is sufficient for that purpose.
Recommended practice for industry
• Mine operators must identify and control the risks associated with work in and around underground sumps and water bodies.
• The risks associated with underground sumps and water bodies must be managed using the hierarchy of controls.
• Elimination, substitution and engineering controls should be used where reasonably practicable.
• All underground sump drain holes should be appropriately guarded and adequately identified.
• All work involving underground sumps should be appropriately planned, risk assessed, documented and supervised.
• Fit for purpose equipment should be used to block and unblock sump drain holes.
• Mine operators should conduct regular reviews of their mine’s safety management plan to verify critical controls are in place for major hazards.
• Company officers are reminded of the importance of their responsibilities and obligations in regard to section 27 of the Work Health and Safety Act 2011 (NSW) (WHSA).
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