Longwall mine plan a threat to water supply

Sydney Morning Herald
10th June 2009

SYDNEY’S drinking water supply in and around the historic Cataract Dam is about to be undercut by multistorey longwall coalmines, in a case that will test the NSW Government’s willingness to apply its own environmental guidelines.

Packed beneath the pristine reservoir, near Appin, lie tens of millions of tonnes of high-quality coking coal, greatly desired by the Indian steel industry.

Ambitious new plans submitted to the Government from the mining corporation Gujarat NRE would intensify mining in the area for decades to come, tripling the mine’s output.

Advertisement: Story continues below

But cutting out the coal would cause the drinking water catchment, which supplies Sydney and the Illawarra, to crack and tilt due to subsidence, with unknown – though almost certainly negative – effects on the water supply.

The company may have to seriously modify its plans to counter environmental concerns. Government sources told the Herald there was no choice but to try to rein in the company in the face of clear evidence of potential damage to the water catchment area.

As well as foreshadowing damage to waterways, the company’s initial proposal also conceded that there was a “high level of risk” to Telstra fibre optic cables, electricity and water pipelines and roads in the area. “Detailed assessment is warranted to address this high risk rating,” its report said.

The company said it was working out what level of environmental damage could be tolerated, after being told by the Director-General of the Planning Department that it would take into account recommendations of a landmark inquiry into coal mining.

The independent southern coalfields inquiry, released last year, found that mining was causing serious damage in the water catchment and the Government should require a reverse onus of proof on companies seeking to mine in sensitive areas.

Longwall mining, in which broad panels of coal a few metres high and hundreds of metres wide are bored out of the earth, causes ground above the mines to subside.

Above other multi-level mines in NSW, such as the Newstan Colliery near Lake Macquarie, the surface has dropped by as much as five metres in places.

Gujarat NRE’s head of technical services said there was no evidence yet that earlier mining beneath the dam had led to cracking and loss of water, though there could be some undetected “microcracking”.

“If there will be subsidence of a nature that would cause catastrophic damage to a significant surface feature, then we would consider not extracting that,” said Chris Harvey, Gujarat’s head of technical services.

Gujarat NRE has hired consultants to prepare a new report on the environmental impacts of the mine expansion and said it may submit the research for peer review if required.

A spokesman for the planning department said inquiry findings would “form a key part of the department’s assessment of these projects”.

Environment groups and the NSW Opposition believe that mining under the drinking water supply should be stopped or more closely controlled.

“The Gujarat proposal is up there at the extreme end of longwall mining proposals and we know from experiences that there will be serious damage,” said Dave Burgess, a spokesman for the Total Environment Centre.

The NSW Liberal MP, Michael Richardson, said a number of subsidence problems had been “created by single-seam longwall coalmines where reasonable predictions could be made but no such predictions are possible with multi-seam mines”.

“Any damage under Cataract reservoir would be invisible but the water loss would be ongoing and the damage almost certainly irreparable,” Mr Richardson said.

This entry was posted in Newspaper articles or other media. Bookmark the permalink.

Leave a Reply

Your email address will not be published. Required fields are marked *