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Bauxite miner Alcoa’s plans to drill more than 100,000 holes a year as it explores the Darling Ranges have raised the hackle of WA’s mining department, with documents revealing concerns with issues including the impact on native black cockatoos and a lack of communication with stakeholders.
A Department of Mines, Petroleum and Exploration review – released under freedom of information laws and requested by independent news site Boiling Cold – revealed concerns raised during an assessment of environmental review documents for exploration spanning from 2023 to 2027.
Carnaby’s black cockatoos near a pine plantation in Perth.Credit: Miles Tweedie Photography
Those documents stated that there were significant concerns for black cockatoos nesting and feeding in the area.
“Black cockatoos do use (Alcoa’s Mineral Lease 1SA areas) as demonstrated by hundreds of records including roosting and nesting trees identified in the environmental review documents,” DMPE comments revealed.
“Those records are not shown in the Department of Biodiversity, Conservation and Attractions’ dataset.
“To gain an agreed, shared understanding of impacts and longer-term population dynamics, data sharing is required yet this is not happening for the three black cockatoo threatened species.
“Conservation advice and feedback are compromised if data is not being shared with regulators.”
In the documents, the DMPE also said while Alcoa was retaining trees with hollows suitable for black cockatoos and significant trees, assumptions had been made about how the birds would use those trees.
“It is not correct to assume that there are plenty of suitable hollows in the areas surrounding the development envelope and that they are not in use,” the feedback reads.
“Why would the cockatoos observed breeding adjacent to mining areas move out of the way for the now displaced breeding pair (from the retained nest trees while mining is occurring)?
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“The impact assessment ignores the loss of future hollows (from the ones not identified as known/ potential nest trees) from the clearing of 6200 hectares of forest habitat.”
Another concern raised was related to Alcoa’s on-ground actions, including increased feral predator controls and installation of black cockatoo drinking water points, which the US company had stated would provide benefits within around five years.
But the DMPE said those proposed actions “do not address the gradual loss of hollows and breeding habitat over time”.
Alcoa director of regulatory approvals Kane Moyle said the company was increasing its work with stakeholders, including government representatives, to guide the company’s approach to mine planning.
“While exploration drilling is a low-impact activity and does not indicate an intention to mine an area, but rather to broaden geological knowledge of the region, we agree environmental factors must always be considered and responsibly managed to avoid and minimise impacts,” he said.
“Publicly available information submitted to the Environmental Protection Authority as part of our approvals process includes details on the mitigation hierarchy for managing potential impacts on black cockatoos,” he said.
“We have measures in place to protect areas of high conservation value including nesting trees, rocky outcrops and stream zones that provide valuable fauna habitat.
“We are continuing to prepare our responses to submissions as part of the EPA’s formal assessment process, and these will be made available to the public in due course.”
Effect of drilling vibrations on bats called into question
Bats inhabiting the area could also be impacted by Alcoa’s plans, given vibrations from the drilling have not been adequately considered, according to the review.
It was stated vibrations from drilling and mining had impacted cave dwelling bats in the Pilbara, but that it was “unaware of such impacts to fauna in the southwest of WA”.
The DMPE suggested that the Department of Biodiversity, Conservation and Attractions would be better placed to comment.
But later in the review, they noted there was a “noticeable lack of data sharing with DBCA which makes it more difficult than not to have a publicly available and agreed to understanding of population dynamics and trends.”
Another concern was that Alcoa had suggested that “after approximately 12 months, the drill rig path and drill hole location are difficult to identify due to minimal disturbance and natural recovery”.
But the DMPE suggested it would be useful for Alcoa to “provide measurable evidence of that minimal disturbance and natural recovery process”.
The proposal allows for a maximum of 105,000 drill holes per year at 4.5 to 7.5 centimetres in diameter and an average depth of 6 metres.
The comments from the DMPE come after Alcoa’s plans to mine the jarrah forest attracted more than 59,000 submissions to WA’s independent environment watchdog amid a widening public backlash against its activities.
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