An alert over equipment which failed a standard safety test has sparked a review of testing and regulatory procedures. Special investigation by Stephen Bell and Marian Hookham

Australian coal producers — already facing price cuts of up to 18% from Japanese buyers — have been hit by a domestic power supply upheaval that is causing further heartache and financial losses.

The amount of production lost due to the discovery of allegedly unsafe power supply units in underground coal mines is still uncertain. However, government officials concede that more than 50 mines in New South Wales and Queensland have been affected by the disruption. On Christmas Eve, the Department of Mineral Resources in NSW ordered that two types of Austdac intrinsically safe (IS) power supply units be immediately removed from service in the state’s coal mines, due to worries about the risks of gas explosions. With the spectre of the Gretley coal disaster still hanging over the Inspectorate, the DMR argues it had no option but to quickly ban the offending units.

But the DMR’s action at the start of the holiday season threw the NSW industry into chaos, forcing many mines to shut production down while they frantically searched for alternative power supplies. Shell’s Dartbrook operation in the Hunter Valley and the West Wallsend mine near Newcastle appear to have been among the worst impacted.

Some coal miners have criticised the department for being heavy-handed, particularly in light of the more lenient approach taken by the Queensland authorities. Rather than a blanket ban, the Queensland Department of Mines and Energy allowed its coal mines to continue using the IS power supply units, provided they could prove there were no safety risks for employees.

“They (Queensland) gave them (miners) a period of time to do a risk assessment, which I think was a better alternative,” said Glen Lewis, mine manager at Cumnock. Cumnock endured a short stoppage in order to fit new power units. “These (IS power units) had been operating in the mines without incident. Had we been able to do an on-site risk assessment, I wouldn’t have stopped mining at all. This mine has no gas and never has had any, so the risk would be extremely low.”

The power supply scandal has come at a sensitive time for the NSW coal industry inspectorate, which has been criticised over the 1996 Gretley colliery disaster in which four miners died. According to industry sources, the Gretley-inspired sensitivity about safety issues is probably one reason why the DMR inspectorate acted so hastily over the IS power supply issue. But Neville Sneddon, the DMR’s assistant director of safety operations, was unrepentant about the department’s actions, instigated by one of the power units failing a standard “spark test” at Londonderry, an independent testing laboratory.

“Those IS power units are used in mine areas where there are potential exposures to explosive methane mixtures,” he told Australia’s Longwalls.

“If we find that they are not in compliance with the standards, we have a legal responsibility to have them removed. We are relieved, as much as anything, that we picked the thing up before there was some sort of an accident.”

Sneddon declined to comment on Queensland’s approach. “But I will say these power units are used in a position where they are most exposed to something going wrong. From my personal point of view, you wouldn’t forgive yourself if you had an apprehension of that and didn’t do something.”

In its safety alert to mine managers sent out on Christmas Eve, the DMR stated that an Austdac power supply unit failed a test at Londonderry on Wednesday, December 23. During the test, an “explosive mixture of gas was ignited with an output current significantly lower than 1 ampere”

“The apparatus cannot be considered intrinsically safe, and apparatus and cables connected to the power supplies may cause the ignition of flammable gases,” the notice said.

The DMR ordered that all Austdac PSU00018 and 00019 power supplies be immediately removed from service and de-energised.

According to some in the industry, the DMR badly misjudged the impact of its notice, which linked the Austdac power units to gas monitoring systems.

“They didn’t realise that these units supply power to many longwalls in Australia,” said Cumnock’s Lewis. At his mine, and many others, the units power the chock control units for longwall face supports. As such, they are a key part of the production cycle.

“They (DMR) thought they were dealing with a power supply for (gas) monitoring equipment. But when they sent out the notice saying we had to remove all these IS power supplies, it made my longwall and certainly many in NSW out of compliance,” Lewis said.

Sneddon denied the department had erred. “We made a judgement on the impact of continuing to use these units in circumstances where they weren’t safe. If we had an ignition of methane resulting from the use of things, after we’d found out that they didn’t comply with the standards, I think you’d have had a different story. That is the tough position we were in with this sort of thing.”

For some mines, the disruption was little more than an inconvenience. “We have only two of those IS power supplies in the mine,” said Lewis. “We were lucky enough to get hold of two other suppliers’ units and we changed them that afternoon.”

Ironically, some of the of the most modern mines were worst hit. “It has been the people with the most up-to-date equipment — the newest longwalls —that actually had the biggest problem,” said Sneddon. “Because they have put more automation into their systems, and automation requires power supplies.”

David Reece, mine manager at Dartbrook, said his mine used two of the revoked power supply units on every eight roof supports. “When that unit could not be used, we no longer had the electronic operation of the supports. We could have operated them manually, but that raises some safety issues, where people are physically on a roof support as it is moving.”

Reece said Dartbrook lost about a day-and-a-half of full production. At that stage, it managed to re-start operations on a reduced basis by installing alternative power systems.

“We were then able to maintain a limited operation of the face. That meant we could continue on a slower cycle time. That kept us going for about five weeks until they’d sorted the mess out.”

As of early March, the reduced power supplies were still restricting Dartbrook’s output, though mine officials declined to quantify the precise impact.