A mammoth mothballed goldmine in Reefton is starting to disappear under a new forest canopy.
Around three quarters of the former Globe Progress mine has undergone restoration work so far, as part of meeting consent requirements.
It’s the first large scale modern open pit mine in the South Island to move into closure and rehabilitation and mining company OceanaGold hopes the project will be a model for others to follow.
“When we first started, there was very little knowledge about large scale beech forest restorations. So during the course of the operation we've had to do a lot of adaptive management and learning from our own research,” explains Restoration and Environmental Coordinator Steph Hayton.
More than 600,000 seedlings have been planted so far on the 250 hectare area, with hundreds of thousands more to come.
As part of its access agreement with the Department of Conservation, the company must meet certain criteria. That includes having more than 75 per cent canopy cover of the ground area, a dominance of native species, and evidence of natural regeneration taking place.
OceanaGold is also treating water in the Globe Progress pit, which is being turned into a lake. The aim is to get mineral concentration levels lower than the required downstream limits.
Canterbury University Professor David Norton has been involved with the project from the beginning, writing the original restoration plan for the site and keeping tabs on its progress.
He says mine sites “are particularly challenging for restoration”.
“The whole environment's been altered. You've dug up a big hole in the ground, you've created these big rock stacks and the land forms are totally different to what you would have had originally."
But Professor Norton believes the work is progressing well.
“I've seen a lot of old mine sites on the West Coast that have been abandoned. They've gone into gorse and not much else. There's been no soil spread, they've done very poorly."
He says the Reefton site is “looking really healthy”, with some areas achieving 100 per cent canopy closure and “a real nice forest understorey environment, lots of regeneration”.
But he points out that it is the “minimum” that should be expected if there is to be future mining activity in the country.
“Restoration shouldn't be an excuse for destroying nature, it should be the last part of the process."
Forest and Bird agrees, stressing what is lost during an operation cannot be overlooked.
“When you remove a forest, you remove all life. And then when you're starting again, you’ve got to talk about hundreds of years before you can bring something back that was there before,” says Top of the South Island Regional Manager Debs Martin.
“So that can be large old trees with hollows in or burrows underneath. There might be kiwi or long-tailed bats roosting in the hollows of the trees."
So far OceanaGold has spent tens of millions of dollars on the restoration work.
Steph Hayton says while the mine can’t be put it back to what it was, “you can probably put it back to something as good, it's just slightly different”.
Full restoration is estimated to take at least three more years.
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