WA's environment regulator will not prosecute US miner Alcoa for secretly and illegally pumping toxic "forever chemical" PFAS over a drinking water dam in the state's South West.
Instead, in December 2024, the regulator sent Alcoa a warning letter for an action Water Corporation labelled "an unacceptable risk to drinking water quality."
In 2022, Alcoa built a pipeline over Water Corporation's Samson Brook Dam near Waroona to move PFAS-contaminated water from its Willowdale bauxite mine.
The regulator said there was "a real and not remote possibility" of PFAS-contaminated water leaking through pipeline joints or "through loss of pipeline integrity."
This was made more likely as Alcoa laid the pipeline along the edge of a road where it could easily be damaged by a vehicle.
A leak near the causeway crossing Samson Dam could allow the contaminated water to flow into the dam and then enter the integrated water supply system that serves the South West of WA.
Alcoa's bauxite mines in WA are contaminated by PFAS contained in firefighting foam that it no longer uses.
A DWER spokesman said its investigation concluded there was evidence Alcoa breached section 53(2)(a) of the Environmental Protection Act by constructing the pipeline without its approval.
He said its decision to send a letter rather than launch a prosecution was made in accordance with its Compliance and Enforcement Policy.
Considerations in the policy include the seriousness and environmental impact of the alleged offence and the behaviour of the alleged offender, such as cooperation with DWER, compliance with notices and implementation of mitigation measures.
DWER declined to supply a copy of the warning letter or give details on how consideration of its policy led to a decision not to prosecute.
Alcoa declined to comment on the pipeline it built. It has now been removed after a directive from DWER.
The miner now trucks the contaminated water to a treatment plant it has built.
An Alcoa spokesman said the plant was commissioned on January 31 and will produce water with PFAS levels more than 300 times lower than required by the Australian Drinking Water Guidelines.
These are the same guidelines that last week Boiling Cold revealed the WA government had abandoned when assessing Alcoa's mining in water catchments to avoid restricting its bauxite production.
The treated water is disposed of in McKnoes Brook.
Environment minister Reece Whitby was asked if he supported the decision of his department not to prosecute Alcoa.
His spokesman said a decision to prosecute was entirely for the agencies involved, and it would be inappropriate for him to comment.
I worked in oil & gas in commercial and engineering roles for 20 years. Since 2016 I have written for The West Australian, The Saturday Paper, RenewEconomy, Michael West, Boiling Cold and WAtoday.
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