CASE STUDIES

What can we learn from elsewhere?

Experiences from other major projects can reveal questions worth asking before impacts occur and while environmental assessment is still underway.

These case studies examine documented environmental, regulatory and community experiences and consider what lessons they may hold for the proposed Gonneville Project.

CASE STUDY 01 — PINJARRA

THE BASELINE YOU CAN'T COLLECT AFTERWARDS

Dust, air quality and residential rainwater

Western Australia already has a real world example of why comprehensive baseline monitoring matters before a major industrial development begins.

Residents around Alcoa's Pinjarra Alumina Refinery raised concerns about dust, health and possible contamination. Over time, those concerns led to residential sampling, Department of Health investigation and increasingly detailed air quality monitoring by DWER.

One investigation followed the detection of elevated lead and mercury in a resident's rainwater tank. DWER investigated whether airborne refinery dust was responsible but did not establish Alcoa dust as the source.

That outcome highlights an important problem:

Detecting something after an industrial operation is established does not necessarily tell investigators where it came from or whether concentrations have changed.

THE HISTORICAL EVIDENCE GAP

When the WA Department of Health investigated community health concerns around Pinjarra, it identified an important limitation: there were very few historical monitoring data showing actual concentrations of particles and gases in surrounding communities.

Later monitoring could measure current conditions.

It could not recreate the environmental baseline that had never been measured.

This distinction matters.

Predictive modelling can estimate what concentrations may occur. Baseline monitoring records what was actually present before conditions changed. Operational monitoring records what is present after development begins.

Without suitable pre development measurements, determining whether environmental conditions have changed and potentially identifying the source of that change can become much more difficult.

THE RAINWATER TANK INVESTIGATION

The Pinjarra case became particularly relevant to rural households when elevated lead and mercury were detected in water collected from a resident's rainwater tank in late 2021 and again in 2022.

DWER investigated whether airborne dust associated with Alcoa's operations could have been responsible. Dust samples were collected from the property, including locations closer to the refinery than the rainwater tank.

The investigation did not establish Alcoa dust as the source of the detected lead and mercury.

That finding is important, but so is the difficulty the investigation illustrates.

Once something is detected in a rainwater tank, investigators must determine where it came from. Potential sources can include natural soil and dust, smoke, roads, roofing or plumbing materials, agriculture, industry, or a combination of sources.

Without suitable pre-development measurements, a fundamental question can become difficult to answer:

Was it there before the industrial development began?

WHEN A DUST EVENT IS ALREADY OVER

The Pinjarra investigations also exposed another practical problem with retrospective monitoring.

In December 2023, DWER returned to investigate further reported dust impacts at a residential property. However, insufficient dust could be collected for laboratory analysis, and the investigation was therefore inconclusive.

This illustrates why responding to complaints after a dust event is not necessarily enough.

By the time investigators arrive, the material needed to determine what occurred and potentially where it came from may no longer be available.

WHAT HAPPENED NEXT

As community concerns continued, government monitoring became progressively more detailed.

DWER undertook ambient air monitoring around Pinjarra during 2023–24, followed by a six-month monitoring campaign from November 2024 to April 2025. The later campaign deliberately covered the warmer period, including conditions with frequent easterly winds when dust impacts could be greater.

Monitoring went beyond simply measuring “dust”. It included PM₁₀, PM₂.₅, deposited dust, metals, respirable crystalline silica, gases and meteorological conditions, with comparison against background conditions.

The Department of Health reviewed the results and advised that the concentrations measured during the campaign did not represent a public health risk.

But the later monitoring could only establish conditions at the time it was undertaken.

It could not recreate the historical baseline that had never been measured.

That is the important lesson for a project like Gonneville where the opportunity to establish that baseline still exists.

WHAT PINJARRA MEANS FOR GONNEVILLE

Pinjarra does not prove that Gonneville will cause harmful dust exposure or contaminate rainwater.

It demonstrates something different: how difficult environmental questions can become to answer retrospectively when the historical measurements needed to answer them do not exist.

Gonneville has not yet commenced mining. The opportunity still exists to establish robust baseline conditions before large scale operations begin.

If concerns arise in the future, that evidence could help determine what changed, when it changed and whether the project is a plausible source.

Pinjarra's lesson is simple:

THE BASELINE CANNOT BE COLLECTED AFTERWARDS.

Status: Ongoing case study. This page will be updated as new information becomes available.

SOURCES

https://www.wa.gov.au/government/publications/pinjarra-air-quality

https://www.wa.gov.au/government/publications/ambient-dust-monitoring-campaign-pinjarra

https://www.health.wa.gov.au/~/media/Corp/Documents/Reports-and-publications/Shire-of-Murray/Evaluation-of-Cancers-and-Other-Health-Conditions-in-Shire-of-Murray.pdf

CASE STUDY 02 — ECONOMICS

THE TRUE COST OF A MINE

The billion-dollar question behind Gonneville

$820 million.

That is Chalice Mining's estimated Stage 1 development capital for Gonneville in its December 2025 Pre-Feasibility Study.

It sounds like the price of building the mine.

But it isn't the whole capital story.

The same PFS estimates:

$820 million Stage 1 development capital,

$840 million Stage 2 development capital,

$30 million Stage 1 sustaining capital,

$570 million Stage 2 sustaining capital.

Together, those published estimates amount to approximately:

$2.26 BILLION

in nominal development and sustaining capital across the modelled two-stage open-pit operation.

That does not mean $2.26 billion is required upfront. Stage 2 occurs later, and sustaining capital is spent progressively during operations.

But it does raise an important question:

When the economic benefits of Gonneville are discussed, are we seeing the complete economic picture?

Gonneville is a proposed greenfield development requiring not only a mine and processing plant, but substantial supporting infrastructure.

Power.

Water.

Roads and transport.

Off-site infrastructure connections.

Land access.

And potentially infrastructure involving third parties or government.

At the same time, major economic benefits are being attributed to Gonneville through economic modelling whose headline findings have been publicised, while the complete underlying economic impact study has not been made publicly available for independent examination.

So we decided to look beyond the headline numbers.

What will Gonneville actually require to build and operate — what is included in the published capital estimates, what sits outside them, and who ultimately pays?

THE $95 MILLION QUESTION

Buried inside Gonneville's Stage 1 capital estimate is a figure that deserves a closer look.

Infrastructure: $95 million.

According to Chalice's Pre-Feasibility Study, the $820 million Stage 1 development capital is divided across mining, the processing plant, tailings storage, infrastructure, indirect and owner's costs, and contingency.

The Stage 1 infrastructure allowance is $95 million.

But Gonneville requires substantial infrastructure to operate.

Chalice's own project information describes:

a new approximately 63 km water pipeline from the Alkimos wastewater treatment plant

a new approximately 27 km dual transmission line connecting the project towards the South West Interconnected System

onsite hybrid solar-battery generation with diesel peaking

transport of processed materials to ports

upgrades to local roads

Earlier project disclosures have also stated that Chalice was engaging with the WA and Commonwealth Governments about potential common-user infrastructure options and funding support.

None of this proves that infrastructure expenditure has been omitted from the PFS.

But it creates an obvious question.

WHAT EXACTLY DOES THE $95 MILLION INCLUDE?

Does it include the complete cost of constructing the proposed off-site power connection?

Does it include the complete water pipeline?

Does it include land access and corridor establishment?

What road upgrades are included?

What infrastructure would instead be constructed, owned or funded by utilities or other third parties?

And is any infrastructure required by Gonneville expected to involve government funding, co-investment or other public expenditure?

Those distinctions matter.

If infrastructure required to enable a mine is funded outside the mine's own development capital estimate, that does not make the infrastructure cost disappear.

It changes where the cost sits, and potentially who pays it.

A QUESTION THAT DESERVES A CLEAR ANSWER

Before the economic benefits of Gonneville are weighed against its costs, the community should be able to see a clear breakdown of:

what infrastructure Gonneville requires, what it will cost, where those costs appear in the project's financial estimates, and who is expected to fund them.

Until that information is clear, the $95 million infrastructure line raises more questions than it answers.

THE COST HAS CHANGED

Gonneville has not always carried an $820 million starting price.

The 2023 Scoping Study considered development options with initial capital estimates of approximately $1.6 billion to $2.3 billion, with further expansion capital of $1.1 billion to $1.9 billion.

The project has changed significantly since then, including a simplified processing flowsheet, so these figures cannot be directly compared with today's PFS.

But they demonstrate something important:

Gonneville's design and its cost has continued to evolve.

With the full Feasibility Study still to come, the current $820 million Stage 1 estimate should not be mistaken for a final construction price.

THE REPORT YOU CAN'T SEE

In June 2026, Lawrence Consulting completed a new Economic Impact Study for Gonneville using inputs from the project's PFS.

Its headline findings have been promoted publicly, including:

$24.1 billion contribution to WA's economy

3,761 direct and indirect jobs supported on average

$7.7 billion in purchases from more than 1,200 local businesses

But the complete study has not been publicly released for independent scrutiny.

That matters.

Without the full report, it is difficult to examine the assumptions and methodology behind those numbers, including what “local” means, where expenditure is expected to occur, what infrastructure assumptions were used and what costs were considered.

If these figures are being used to demonstrate Gonneville's economic benefit, the community should be able to see how they were calculated.

DO THE NUMBERS ADD UP?

Gonneville is being promoted with some very big economic numbers.

But the $820 million Stage 1 figure is only one part of a much larger capital picture.

The PFS identifies further Stage 2 and sustaining capital. Major infrastructure is still being planned. Funding arrangements are still developing. And the final Feasibility Study is yet to come.

Meanwhile, billions of dollars in economic benefits are being attributed to the project through modelling that the public cannot fully examine because the complete Economic Impact Study has not been released.

That doesn't mean the economic claims are wrong.

It means we cannot yet see the whole equation.

Before Gonneville's economic benefits are accepted at face value, the community deserves to know the full cost of the project, what sits inside and outside the published estimates, whether public or third-party funding will be required, and the assumptions behind the benefits being claimed.

**The benefits are being publicised.

The full picture should be too.**