Take a look inside the rehabilitation work of one of the world’s largest bauxite mines

In the ongoing expansion of Alcoa Australia the mining giant is working to extract 27 million tonnes of bauxite ore from its Huntly mine on the outskirts of Pinjarra and another 10 million tonnes from its Willowdale site only a short drive from Waroona.

When established in 1976, Huntly was the second mine of its type in Western Australia, and in under 60 years, it has become not only the largest bauxite mine in the State but one of the largest in the world.

Through its expansion, Alcoa has made an ongoing effort to restore the jarrah forest to the levels required by the State Government, a benchmark which has shifted through the years.

Before the push for bauxite, the forests were harvested for timber, with tuart, jarrah and marri trees felled across 95 per cent of the northern jarrah forests since the days of European colonisation.

Forest restoration existed when the mines began, but were managed as a timber resource, with predominantly eastern tree species planted in distinct rows for later harvesting.

It wasn’t until after 1988 the Department of Conservation and Land Management, now the Department of Biodiversity, Conservation and Attractions, shifted the required rehabilitation targets to focus on biodiversity.

Alcoa environment manager Luke Gossage said the company was at the forefront of watching science evolve as they began looking at species’ richness and biodiversity.

A major advancement in Alcoa’s rehabilitation work was the retention of topsoil salvaged before bauxite was excavated.

“Topsoil is gold to Alcoa,” Mr Gossage said.

He said the first 300mm of soil removed contained an abundance of resources critical in restoring forests, with 60 per cent of the species found in restored forests coming from seeds and bulbs contained in the preserved topsoil.

He said the gathered topsoil could be stockpiled for three months before being returned to an area for rehabilitation.

The remaining 40 per cent of forests are replanted by hand as seeds and seedlings in rehabilitation areas.

Mr Gossage said ongoing efforts had shown signs of success with native animals also, with a 100 per cent mammal return rate in rehabilitated forests and a 90 per cent return rate for reptiles and birds.

He said if trees showed evidence they could be used as habitat for the three endangered species of endemic black cockatoos it would be entirely avoided by mining operations.

Despite the ongoing rehabilitation efforts, some have called for an immediate end to the expansion of forest mining due to concerns about the wider ecological community.

The WA Forest Alliance, working as part of the End Forest Mining Expansion campaign, in a statement said “to date, none of Alcoa’s rehabilitation has been signed off by the WA Government as successfully completed in their 60 years of mining”.

Alcoa environmental scientist Amber Pattinson said while that may be the case, an area not being handed back did not mean it had not been rehabilitated.

She said 75 per cent of cleared land had been rehabilitated, with the company working with the DBCA to manage the forest and some of Alcoa’s rehabilitation area was being utilised within a dirt bike trail in Dwellingup managed by the department.

“The complexity we’ve got at Alcoa is because we’re mining in pods and the DBCA manage forest in lots, we have to wait for an entire area to be rehabilitated,” she said.

She said an area could not be handed back until the rehabilitation was at least 12 years old, often leading to an overlap with new development.

Despite this the WAFA points to a recent independent study published in the Journal of the Society for Ecological Restoration, which states based on more than 35 years of data the mining giant’s restoration efforts are sub-par, only scoring two out of five stars in the study’s restoration targets.

The study claimed returning mined pods to a functional jarrah forest may not be possible due to the removal of the essential bauxitic substrate.

“These substandard restoration outcomes may result from removing the deep, multi-layered bauxitic substrate on which the ecosystem evolved,” the study states.

WAFA senior campaigner Jason Fowler said the State Government needed to halt bauxite mining expansion.

“The forest that remains must be protected if we want to have safe drinking water, climate, nature and continued access to Perth residents’ favourite weekend destination,” he said.