Water, oil and gases leaking into Maltby Colliery disrupted work on a new face and could cut profits for owners Hargreaves Services by up to £16 million.
Hargreaves says the volume of water and other substances leaking in rose after miners had driven an underground roadway just over a mile into a new area of the pit so that work could start on extracting the next panel of coal.
The company said: “Following careful consideration of the health and safety and operational risks, a decision has been taken to abandon further development on the tailgate and to pull the face back to a safe point.
“Maltby has never encountered such conditions before and the issue appears to be localised to this section of the mine.”
Hargreaves chief executive Gordon Banham said: “Whilst we are bitterly disappointed by this development, health and safety concerns far outweigh those of operational or financial performance.
“I am confident that this was the right decision and also that there was nothing that could have been done by the mining team to foresee or avoid this situation.”
Production division director Gerry Huitson added that what had happened at Maltby was very unusual and had never happened before in the pit’s 100 year history.
“No one on the mining team, including our independent expert geologist with 32 years experience at many different UK mines, has come across these conditions before. We will revise the mining plans to avoid this locality and it is highly unlikely that these conditions will be found again in any subsequent panels,” said Mr Huitson.
Hargreaves says there could be a gap of between 12 and 16 weeks between completing coal extraction from the current face and production starting on the new face. The delay will cost the company around £1 million a week in profits.
The company adds that it is continuing to review the short and medium term plans for Maltby, but the gap in production should not affect the pit’s longer term viability.