Hole Truth: After the coal is gone

Coalfields in the Hunter.
Coalfields in the Hunter.
Coalfields in the Hunter.

Coalfields in the Hunter.

Pepe Clarke, chief executive NSW Nature Conservation Council.

Pepe Clarke, chief executive NSW Nature Conservation Council.

THE Hunter Region has had its focus in the air in the past few years when considering the cumulative impact of coalmining on communities and the environment.

Dust exceedances and the impact of dust on people's health have dominated the headlines.

But it's from up in the air that possibly a bigger problem - and certainly a much longer term one - is apparent: the impact of digging up billions of cubic metres of soil in a concentrated area over just a few decades.

There's the barren voids created by active open-cut mines and knowledge that even 1000 years from now, according to NSW government estimates, more than 1200 hectares will still be that way, complete with saline "lakes".

Increasingly scientists are also raising concerns about the long-term impact underground, at aquifer level. And it's the "never-never" nature of responsibility for those impacts, despite the march of coalmine approvals, that has environmentalists taking extreme steps to sound the alarm.

Large open-cut mines depressurise aquifers and cause millions of litres of groundwater to seep into the voids they leave long after mining ends. But governments have accepted mining industry arguments that backfilling voids, which can be 200 metres deep and kilometres long, would be financially crippling.

These voids differ from natural lakes in a significant way, caused by the steep walls and depths of open-cut mines.

Natural lakes have a ratio of depth to surface area of about 5 per cent. Post-mining voids range from 10 to 40 per cent.

THESE "post-mining voids", complete with projected saline "lakes", are recognised as part of the mine approval process. They are as a legacy of the Hunter coal boom.

But at what cost to the environment?

In an important study in 2004, which was the first of its kind, Long-term final void salinity prediction for a post-mining landscape in the Hunter Valley, Newcastle University Associate Professor Greg Hancock painted a disturbing picture of the region's future, long after coal.

It was what he couldn't predict - the future unknown impacts - that was of most concern.

"The long-term water-quality implications for these final voids and their impact on the surrounding hydrological system are largely unknown," Hancock said in 2004.

"There has been very little research into the long-term [in this study hundreds of years] water-quality issues that arise from opencast mining and no risk assessment has been conducted."

His research attempted to predict some of the unknowns based on figures at the state's largest mine, Mount Arthur on Muswellbrook's outskirts, where about 1.9 billion cubic metres of disturbed material, including coal, will be produced over the life of the mine.

What Hancock's modelling could predict was that high saline levels will increase over centuries so that 500 years from now salinity levels at Mount Arthur will peak at 13,250mg/litre, where seawater is about 35,000mg/litre. On current definitions 13,250mg/litre is unsuitable for any uses.

The Mount Arthur final void, according to an environmental impact statement produced in the year 2000, will be 4 kilometres long, 680 metres wide at its broadest point, and about 180 metres deep. Water will only reach 120 metres deep.

Hancock and others have concluded that "it is likely that the void will continue to be a net sink for groundwater in the long-term and will impact upon the Hunter River by reducing the annual flow".

And that's just one mine.

In November last year Anglo American's 4000-page environmental impact statement for the proposed Drayton South mine, about 10 kilometres outside Muswellbrook, was put on public exhibition.

In a 265-page section on groundwater, consultants said the 214-hectare surface area of the Drayton South final voids would act as a "sink" for groundwater for 700 years, and have an impact on the Hunter River.

After 120 years, water in its "lake" is expected to have 5600mg of dissolved solids including salts per litre, which is regarded as being suitable for industrial use.

The acceptance of long-term projections like these to inform decision-making by politicians and bureaucrats, based on modelling alone, astounds environmentalists like NSW Nature Conservation Council chief executive Pepe Clarke.

"It's just considered normal to leave these voids for centuries, and that's a relatively new thing based on the kind of mining we're seeing and its concentration in the Hunter Valley," Clarke said.

"The lasting impact of these mining voids is exceptional, and yet there's been no public discussion with the community by government about whether this is acceptable.

"Each mine approval lasts for, say, 25 years, but it leaves a giant hole filled with a toxic lake that lasts for centuries. Each new mine talks about the impact of its activities, but where is the government looking at the impact of these decisions on the environment as a whole and waterways like the Hunter River?

"And when the mine closes, what happens then? It's the people of the Hunter who are left to live with this problem for centuries to come. Our children. Their children, and their children, and generations after them. Not the mining companies. Not the government."

Newcastle environmentalist Jonathan Moylan's controversial ANZ Bank hoax to highlight the proposed Maules Creek coalmine in part of the Leard State Forest included his strong objection to a final void more than 300 metres deep, Clarke said.

"What we are seeing is that the number and size of these things is increasing exponentially with the number and size of the mine proposals," he said.

IT IS the responsibility of the NSW Division of Resources and Energy to ensure that coalmine land "is returned to a sustainable post-mine land use".

Under the Mining Act 1992 it is responsible for managing environmental security bonds lodged by mining companies, which can be used if companies fail, or fail to meet their obligations. Coalmine agreements require companies to accept responsibility in perpetuity.

But as the Hunter has seen as recently as November last year with the case of a Gillieston Heights family and subsidence from an old mine, the more time that passes after a mine closes, the more likely that lines of responsibility for negative mine impacts are obscured.

The Neale family has lodged an appeal with the Land and Environment Court after the Mine Subsidence Board refused to pay compensation when their $800,000 home was declared unsafe because of damage from the old East Greta coalmine that closed in the 1920s.

During drilling in 2009 to determine the extent of the old mine workings a geyser of water shot from a drill hole.

When it rains water bubbles to the surface from the drill holes at the Gillieston Heights property, about 100 millimetres wide, and pools around the house.

"The old mine workings are filled with water, when you drop a rock down one of the dozen or so drill holes, you eventually hear it splash at the bottom," Andrew Neale said.

"The whole yard is sinking."

A Mine Subsidence Board spokesman said the board had done "everything we can under the act".

That kind of response makes a mockery of government decisions where environmental outcomes like salinity levels in final voids aren't peaking until centuries later, Pepe Clarke said.

"Anything that's said or put in place now is meaningless when we're talking about consequences 1000 years in the future."

Dr Daniel Franks is senior research fellow with the University of Queensland's centre for social responsibility in mining.

He is familiar with mining issues in the Hunter Region, and included Hunter initiatives in a 2012 study about how governments should manage cumulative impacts of mining on local and regional communities.

The Hunter River Salinity Trading Scheme, which allows coalmines to purchase credits to release saline discharges into waterways depending on river flow conditions, was an example of a government initiative that appeared to be working, Dr Franks said.

The concentration and expansion of mining in the Hunter, compared with Queensland's Bowen Basin, which is about 10 times larger in size, meant the community was much more aware of the negative impacts of mining, he said.

One of the biggest problems for the mining industry and the NSW Government, which relies on mine royalties to keep the economy moving, is that the economic benefits argument for mining is under serious challenge because of the obvious negative social and environmental impacts of mining in the Hunter region.

Dust exceedances, mine-related road deaths, final voids with toxic lakes and threats to other industries were being seen as too high a price to pay for keeping people in jobs.

"The value proposition for further expansion of mining in the Hunter Valley is changing, as many of the positive impacts for local communities - such as employment and business development - are reaching saturation, while negative amenity and environmental impacts continue to be generated," Dr Franks said.

He argued that the environmental legacies of mining could be managed better. But he said a considerable percentage of the population still accepted the negative impacts "in exchange for economic benefit and access to the resources we all consume".

The negative impacts included surface and groundwater.

"There needs to be a shift in how we think about the value of resources and the balance between who experiences costs and benefits," he said.

In its submission to the Drayton South proposal, Muswellbrook Shire Council, headed by mayor Martin Rush, objected to the mine, in part because the proposal "falls well short of best practice" relating to final landform, including having three final voids, and rehabilitation.

"Council submits that the final landform voids represent a substantial and permanent environmental detriment and the project makes no sensible attempt to minimise its voids," the council argued.

"It is legitimate to refuse development consent, in conjunction with other principles of public interest, for that reason."

Anglo American this week said it would complete a mine closure plan for the Drayton mine "in line with completion and rehabilitation criteria agreed by key stakeholders and regulatory authorities".

"It is our priority to meet the agreed criteria and then safely relinquish the lease," a spokeswoman said.

"Our mine closure plan will demonstrate the area is safe, stable and without pollutants, and meets the agreed post mining land use.

"Our rehabilitation commitments for the Drayton mine voids include regrading highwalls to sustainable levels and protecting groundwater. Voids will be backfilled, used for tailings from Drayton South or used for water storage."

In its submission to the Drayton South assessment process being undertaken by the NSW Department of Planning, the NSW Office of Environment and Heritage included comment about Saddlers Creek, a section of which is upstream from the proposed Drayton South mine, and downstream from Mount Arthur mine.

It is covered by the Saddlers Creek Conservation Area, which "protects threatened biodiversity on the Mount Arthur Coal Complex Mine Lease".

Drayton South will "reduce the Saddlers Creek catchment by 14 per cent over the life of the project", and nearby Saltwater Creek by 11 per cent. After restoration, Saddlers Creek's catchment would be permanently reduced by 10 per cent.

The Office of Environment and Heritage submission noted: "Interestingly, the assessment of poor water quality and low biological activity in Saddlers Creek downstream of areas of rehabilitation from the Mount Arthur lease suggests that restoration of this aquatic ecosystem and riparian corridor will take considerable time and effort".

But it did not oppose the Drayton South project.


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