YANCOAL’S troubled Austar underground coking coal mine is facing an uncertain future after the Resources Regulator said it was “not satisfied” workers were safe following repeated coal burst events in 2018 similar to an incident that killed two Austar mine workers in 2014.
Some Austar employees have been redeployed to other Yancoal Hunter sites in the past two weeks after the Regulator prohibited all underground longwall mining at the Paxton mine from May 18 after coal bursts in an area newly approved for mining. Yancoal is challenging the regulator’s action in court.
The prohibition followed a “significant” coal burst event on May 17 where 60 tonnes of material exploded from a longwall face at least 400 metres underground. No mine workers were injured.
Two months earlier the Regulator prohibited cutting at the longwall after a coal burst event on March 16. Six weeks before that a mine employee was treated in hospital for a hand injury after 50 tonnes of coal exploded from a longwall on February 2.
Yancoal was advised on May 18 that the prohibition order would remain in place until a detailed geotechnical assessment was completed and the Resources Regulator was satisfied workers would be protected from further coal bursts.
The Regulator issued a two-line statement on Friday in response to Newcastle Herald questions about Austar’s future.
“The prohibition notice issued on 18 May remains in effect. The Regulator is currently not satisfied that comprehensive risk controls have been implemented by the mine operator to protect workers against the threat of further and escalated coal burst events,” a spokesperson for the Regulator said.
A Mine Safety Inspectorate report after a 2016 coal burst “high potential incident” at Austar named the site as the only Australian mine where a coal burst had been identified. The report said the incident was the fatal coal burst on April 15, 2014 that killed Austar workers James Mitchell, 49, and Phillip Grant, 35.
They died when they were engulfed by coal and rock after a major side wall pressure burst in a longwall development road more than 550 metres underground.
In May this year underground coal operations at Appin were suspended when it became the second Australian mine to record coal bursts.
The prohibition notice issued on 18 May remains in effect. The Regulator is currently not satisfied that comprehensive risk controls have been implemented by the mine operator to protect workers against the threat of further and escalated coal burst events.Resources Regulator on Austar coal mine.
The 2016 Mine Safety Inspectorate report followed a coal burst at Austar on August 19, 2016 after a “pressure bump of significant intensity” which sent up to 12 tonnes of coal exploding from the B2 longwall face nearly 500 metres underground. The incident, in a part of the mine described as the first longwall panel in a “virgin” area of the Greta seam, knocked two workers to the ground with the force of the blast.
The inspectorate report described coal burst as “a sudden and dynamic failure of overstressed coal or rock resulting in the release of stored energy”.
An investigation of the 2016 event by University of NSW Emeritus Professor Jim Galvin, who also co-authored an investigation of the 2014 Austar double fatality, said anecdotal reports suggested coal bursts had occurred throughout the mine’s century of operations. This contradicted a coal burst plan prepared by the mine which said Austar “has not had a history of coal bursts in or around the longwall extraction district”.
Professor Galvin concluded that coal bursts “cannot be predicted” and “further coal bursts of unspecified but possibly greater magnitude during the extraction of longwall B2 cannot be ruled out”.
It was particularly concerning that the 2016 incident occurred in an area assessed as a moderate risk and after a seismic event linked to slippage in a nearby fault system, he said.
“If this is the case, it can have serious implications for managing the risk of coal bursts,” he said.
Standard risk assessments based on observations and behaviours of the longwall face “may be poor indicators of an elevated risk of a coal burst”, he said.
The May 17 incident occurred after the mine gained permission to undertake controlled cutting to test additional controls to mitigate a coal burst risk after the March 16 incident. The permission included maintenance of a 50-metre exclusion zone for workers.
In August, 2017 the Department of Planning approved a modification to the Austar mine allowing longwalls B4-B7 in an area surrounded by active and historic mine workings. Recent coal burst incidents have occurred in the B4 mining area.
The processing of an additional 3.65 million tonnes of coal from the area would “optimise resource recovery at the mine and would maintain Austar mine’s business continuity in the short-time”, and provide continued employment for 270 employees, the department said.
In a statement on Friday in response to questions, Yancoal confirmed it had initiated court action relating to Austar mine and the Resources Regulator’s actions, but declined to give details.
Longwall mining was “yet to recommence in the affected area, while development activity in other areas of the mine has continued”, a spokesperson said.
“We have redeployed a small number of Austar people to neighbouring operations in the interests of supporting our employees while the longwall is down.”
The company confirmed the coal bursts had occurred in the area approved for new mining on August 25, 2017. The employee injured during the February 2 incident “went to hospital to receive stitches to his hand and subsequently returned to work the next morning”.
Asked whether the mine could close once the last coal is mined in areas not connected to the new longwall areas, possibly by 2019, Yancoal said: “We have yet to make any decisions regarding the future of the Austar mine and continue to consider all options. No decisions have been made regarding the future operations of the Austar mine.”
Yancoal said it had previously redeployed teams to Singleton’s Ashton mine when longwall mining at Austar was suspended.
“As no decisions have been made regarding the future of the Austar mine, it would be inappropriate to speculate regarding future redeployment strategies,” the spokesperson said.