Strict safety controls have been enforced by the state’s resources regulator as an investigation into what caused methane levels in an underground section of Appin mine to reach near-explosive levels earlier this month continues.
Elevated gas levels were detected at the mine on May 7 – for the second time in seven months – prompting the NSW Resources Regulator to slap a prohibition notice on its operator, South32.
The notice prohibited normal mining operations and prevented miners going underground, except to carry out safety-related inspections and maintenance work.
The incident, related to the withdrawal of workers after a “methane gas exceedance event” that occurred between 10pm and 11pm.
The CFMEU claimed the gas level hit a dangerously-high reading of 4.3 per cent – just 0.7 per cent below the “explosive range”.
A spokesman for the NSW Resources Regulator said the prohibition notice was amended on Thursday last week to allow the longwall to operate for a further 18 metres with “strict controls” in place.
The controls included extra resources in the control room with “specific responsibility for receiving and responding to alarms”, the spokesman said.
“This followed an application from the mine which identified roof stability issues in the location of the stopped longwall, which the regulator considered a significant developing safety issue,” he said.
“Once the new location is reached, the mine will be prohibited from continuing to mine without implementing additional control measures to the satisfaction of inspectors that ensure workers are not exposed to elevated concentrations of methane gas.
“The regulator will continue to work with Appin staff and senior management, as well as the Industry Safety and Health representatives, to resolve the issues.”
South32 last week flagged its overall production of coal would drop substantially due the gas incident.
In a statement to the Australian Stock Exchange (ASX) on May 10, the miner said the amount of production in its Illawarra Metallurgical Coal sector – which is made up of Appin and Dendrobium mines – would be 10 per cent below earlier expectations of 7.9 megatonnes.
Mining at Appin’s Area 7 and 8 longwalls has been suspended, pending an investigation by South32.
“A revised production forecast for Financial Year 2017 will be provided in due course, with the decrease expected to translate directly to sales given low inventory levels,” the ASX statement said.
In late October, operations at the Appin Colliery ceased after a ventilation fan cut out, resulting in a peak methane reading of 4.73 per cent.