Getting revegetation off the ground

Mining has undergone major changes in the wake of the Great Boom.

It has become a forward looking industry, not just in terms of understanding their deposits and how best to ride the commodities waves, but also in terms of, inversely, what they leave behind.

The issues of mine rehabilitation and site remediation are becoming ever more critical in this era of the modern, socially responsible miner, which means planning for the end of the mine, and beyond.

This entails dealing with lingering issues related to excavation, regenerating flora, and making the land viable for other uses if possible.

In the NSW Hunter Valley miners have been trialling innovative grazing programs, introducing soil and vegetation into previously mined areas and turning the remediated land into an agriculturally viable site.

In the NSW Central Ranges, Ulan coal mine’s Bobadeen irrigation scheme is a unique solution to water management that uses surplus mine water to irrigate 242 hectares of land specially planted with perennial pastures.

Another miner has also been working with local wine producers, operating a mine underneath the vineyard.

The Northparkes copper mine, in NSW’s Central West, runs large local cropping operations.

“We farm about 3000 hectares around the mine with no till.  We grow wheat, barley, canola, field peas, and lupins.  The enterprise has been going since ‘97 and I believe the soil’s getting better,” Northparkes Mines farm manager Geoff McCallum said.

“We’ve planted 10,000 trees a year since I’ve been here, so that’s around two hundred thousand trees we’ve planted so far.”

In Canada, Vale has introduced site revegetation programs utilising bees as a method of re-pollinating the local flora, and covering the waste rock and slag left over from years of mining.

There are a myriad of different ways miners are attempting to remediate their old site, and native seeds are part of this process for BHP.

Last year BHP partnered with the Botanic Gardens and Parks Authority (BGPA) to hold an interactive ‘think thank’ as part of a multi-million dollar Restoration Seed Bank Initiative (RSB).

“WA is a global leader in restoration research and the think tank comes as an important time for ensuring the mining industry in WA is leading the world in rehabilitation practices,” BGPA CEO Mark Webb said at the time.

BHP Iron ore’s head of environment Gavin Price added that “a core principal of the RSB is that it is a collaborative, engaging, and locally practiced with global implications”.

The group will examined the latest methods in rehabilitation practices and work towards new solutions for native plant establishment as well as new approaches to the rehabilitation of mined areas.

Speaking to Dr. David Merritt, senior research scientist for BGPA Western Australia, he explained to Australian Mining the shifting views towards conservation and restoration, how miners are rehabilitating their land, and the important role an apparently ever diminishing seed stock is playing in this.

“We’re seeing a diminishing number of seeds and a problem with establishment,” Merritt said.

“We need research into seeds, as they are a finite resource…the seed supply is a limitary factor for restoration.

“We need to recognise earlier the role restoration will play in the long term.”

However the current methods for re-seeding regions are apparently ineffective, and stymieing restoration and remediation.

“With [the current method of] sowing seeds there is between zero to five per cent establishment, maybe ten per cent if we are lucky,” Merritt explained.

“Sowing practices vary, and some aren’t as effective, but it isn’t just about seeding, but also about adopting agricultural practices for seed enhancement and getting them to germinate; about priming them seeds to pollinate.”

Miners simply can’t spread seeds over a wide area and expect the task of remediation to finish there.

“It’s about treating the micro-environment around the seed and preparing it for soil that isn’t in the same state it was prior to mining.”

Despite the importance of the issue, Merritt said some miners are still dragging their feet.

However, “there are good examples, miners who are leading research and revegetation processes, who are redemonstrating both corporate and social responsibility.”

There are many ways for miners to not only fulfil their environmental responsibilities, but in terms of site revegetation “seeds are fundamental to this landscape restoration, and thousands of seeds are needed, but we don’t have enough,” Merritt said.

“We’re on a long journey…a continuous process.”

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