❓ Question regarding Alcoa's PFAS contamination at Willowdale and Huntly Mines, focusing on the extent, impact, and management of the contamination. The answer provides some details, but defers on specifics regarding contaminant levels and reporting dates.
AnsweredQoN 188Legislative Council
QuestionView source ↗
I refer to licence L6465/1989/10 granted to Alcoa in
February 2024 to operate a per- and polyfluoroalkyl substances (PFAS) Treatment Unit in the Willowdale Mine, with the
capacity to treat up to 350 million litres of PFAS contaminated water per year.
Alcoa has also applied for a Works Approval to operate a PFAS Treatment Unit at the Huntly Mine, which is within the Serpentine Dam
Catchment Area. This unit will have capacity to treat up to 2.5 billion litres of
PFAS contaminated water per year. I ask, in relation to each of the Willowdale and Huntly Mines respectively: (a) what specific materials have been contaminated, and where are they located; (b) which dams, areas or water courses do the contaminated areas
drain into; (c) have any of the contaminated areas been identified as potentially impacting drinking water supply infrastructure; (d) if yes to (c), which ones; (e) please provide details of all the contaminants (including PFAS, PFAS derivatives and any
other chemicals) identified by testing at each
mine site, and the respective levels at which they were found to be present; (f) when was each contamination incident first reported; (g) what measures were taken following each report of contamination; (h) what chemicals containing PFAS were used by Alcoa at each
mine site, and for what purpose where they each used for; (i) to the Government's knowledge, has Alcoa ever used chemicals containing PFAS for dust suppression purposes at
its Western Australian mine sites; (j) what chemicals has Alcoa used, or is using at its mine sites now for dust
suppression purposes; (k) what other chemicals has Alcoa used, or is it currently using at each mine
site; (l) in reference to (k), what purpose were, or are, those chemicals used for; and (m) when will the results of the investigations under the Contaminated Sites Act 2003 on the above be made publicly available?
February 2024 to operate a per- and polyfluoroalkyl substances (PFAS) Treatment Unit in the Willowdale Mine, with the
capacity to treat up to 350 million litres of PFAS contaminated water per year.
Alcoa has also applied for a Works Approval to operate a PFAS Treatment Unit at the Huntly Mine, which is within the Serpentine Dam
Catchment Area. This unit will have capacity to treat up to 2.5 billion litres of
PFAS contaminated water per year. I ask, in relation to each of the Willowdale and Huntly Mines respectively: (a) what specific materials have been contaminated, and where are they located; (b) which dams, areas or water courses do the contaminated areas
drain into; (c) have any of the contaminated areas been identified as potentially impacting drinking water supply infrastructure; (d) if yes to (c), which ones; (e) please provide details of all the contaminants (including PFAS, PFAS derivatives and any
other chemicals) identified by testing at each
mine site, and the respective levels at which they were found to be present; (f) when was each contamination incident first reported; (g) what measures were taken following each report of contamination; (h) what chemicals containing PFAS were used by Alcoa at each
mine site, and for what purpose where they each used for; (i) to the Government's knowledge, has Alcoa ever used chemicals containing PFAS for dust suppression purposes at
its Western Australian mine sites; (j) what chemicals has Alcoa used, or is using at its mine sites now for dust
suppression purposes; (k) what other chemicals has Alcoa used, or is it currently using at each mine
site; (l) in reference to (k), what purpose were, or are, those chemicals used for; and (m) when will the results of the investigations under the Contaminated Sites Act 2003 on the above be made publicly available?
AnswerView source ↗
Answered
25 June 2025
Responded by
Minister for the Environment
Response time
8 days
(a) The contaminated materials are mainly stormwater and process water contained within storage dams and sumps, along with isolated areas of soil at Alcoa of Australia’s Huntly and Willowdale mines.
(b) The contaminated water is within operational process dams, sumps and other water bodies, fully contained within Alcoa’s Huntly and Willowdale mine premises.
(c)-(d) No.
(e)-(f) Due to the complexity of the information required, an answer will be provided in the next week of sitting.
(g) The Department of Water and Environmental Regulation (DWER) investigated the incidents however there was insufficient evidence to establish a breach of the EP Act. In September 2020, Alcoa advised DWER that they had ceased the use or discharge of PFAS-contaminated process water and chemicals onsite.
(h) Alcoa has informed DWER that PFAS-containing fire-fighting foam was historically used at the Huntly and Willowdale mines.
(i) Alcoa has advised DWER that, prior to Alcoa becoming aware of the contamination, Alcoa used water containing low levels of PFAS for dust suppression at both mine sites. DWER has not, at any time, given Alcoa approval to use materials containing PFAS for dust suppression.
(j) DWER has only approved Alcoa to use water for dust suppression and is not aware of Alcoa using any other chemicals for dust suppression.
(k)-(l) DWER understands that Alcoa uses fuels, oils and other hydrocarbons at the mine sites as part of their day-to-day operations (such as vehicle refuelling and servicing).
(m) In accordance with the Contaminated Sites Act 2003, all contamination investigation reports held by DWER can be accessed by requesting a detailed summary of records in the prescribed manner.
(b) The contaminated water is within operational process dams, sumps and other water bodies, fully contained within Alcoa’s Huntly and Willowdale mine premises.
(c)-(d) No.
(e)-(f) Due to the complexity of the information required, an answer will be provided in the next week of sitting.
(g) The Department of Water and Environmental Regulation (DWER) investigated the incidents however there was insufficient evidence to establish a breach of the EP Act. In September 2020, Alcoa advised DWER that they had ceased the use or discharge of PFAS-contaminated process water and chemicals onsite.
(h) Alcoa has informed DWER that PFAS-containing fire-fighting foam was historically used at the Huntly and Willowdale mines.
(i) Alcoa has advised DWER that, prior to Alcoa becoming aware of the contamination, Alcoa used water containing low levels of PFAS for dust suppression at both mine sites. DWER has not, at any time, given Alcoa approval to use materials containing PFAS for dust suppression.
(j) DWER has only approved Alcoa to use water for dust suppression and is not aware of Alcoa using any other chemicals for dust suppression.
(k)-(l) DWER understands that Alcoa uses fuels, oils and other hydrocarbons at the mine sites as part of their day-to-day operations (such as vehicle refuelling and servicing).
(m) In accordance with the Contaminated Sites Act 2003, all contamination investigation reports held by DWER can be accessed by requesting a detailed summary of records in the prescribed manner.
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