Western Australia's Department of Water and Environmental Regulation has issued an Environmental Protection Notice against the Mindarie Regional Council over catastrophic mismanagement at Tamala Park Waste Facility. The landfill, which opened 35 years ago in Perth's northern suburbs, is drowning in leachate—the toxic liquid that accumulates in decomposing rubbish—with data from October 2024 showing 167 Olympic-sized swimming pools worth of contaminated liquid pooling at the site's bottom.
The facility has accepted household waste from 800,000 Perth homes for three and a half decades. The council, composed of seven local governments, had expected the landfill to close around 2028. That timeline now appears impossible. Without active removal methods in place, leachate levels have only risen since last year's measurements.
A Regulatory Failure Years in the Making
On August 3, the regulator issued formal notice requiring the council to determine exact leachate levels and submit a removal plan within 30 days. The order also demands improved landfill gas management, updated closure planning, and additional technical investigations. This wasn't a surprise inspection—the council had already requested permission to install a containment liner and leachate management area in early August. DWER rejected it outright.
The regulator's reasoning is damning. A DWER spokesperson stated that "highly elevated leachate levels were a significant consideration during the assessment" and that the council's proposed works "would generate additional leachate and would not adequately address the existing leachate, odour and groundwater issues at the site." Translation: the council's solution would make things worse.
Western Sydney University science professor Ian Wright, a water scientist with 30 years of experience, explained what leachate actually is. "It's the liquid that builds up in rotting rubbish," he said. "It's often a tea-coloured liquid that stinks, and it's basically decomposing waste, and it's chemically full of lots and lots of contaminants." He called the 167 Olympic pools worth of accumulated leachate "a major issue" for groundwater health.
The Gnangara Aquifer at Risk
The real alarm bell here is the landfill's proximity to the Gnangara aquifer, which supplies almost half of all water used across the Perth metropolitan area annually. Wright expressed surprise that the facility—opened in 1991—was only partially lined. "It's easy for waste from something like this landfill to move through sand down to the aquifer, so as to contaminate the groundwater," he said.
DWER acknowledges ongoing investigations into groundwater contamination but claims current human health risk is "low." That's cold comfort when the infrastructure protecting Perth's water supply is demonstrably inadequate and leachate continues accumulating unchecked.
The Methane Problem Nobody's Talking About
Leachate isn't the only hazard. As organic waste breaks down in anaerobic conditions deep underground, it produces methane—a gas with three distinct dangers. It's a potent greenhouse gas. It stinks, creating nuisance conditions for surrounding suburbs. And it's explosive.
Wright warned that methane can rise through soil layers and even penetrate concrete slabs in nearby buildings. "It can build up to explosive levels," he said. The fact that residential suburbs have grown around this facility without adequate buffer zones is a planning failure that compounds the environmental problem.
The Council's Inadequate Response
A Mindarie Regional Council spokesperson said the organization is taking landfill management "extremely seriously" and that elevated leachate levels have been "aware of for some time." They claim they've worked with DWER for several years to monitor and manage risks. Yet they couldn't even quantify how much leachate sits at the bottom of their own facility until the regulator forced the issue.
The council says it's deploying measures to control leachate generation, prioritizing capping of open areas, and optimizing odor management. These are band-aid solutions to a structural crisis.
Resident Mary O'Byrne, who has been campaigning against odor and environmental concerns for years, cut to the heart of the issue: "My concern is the groundwater, what's happening to that, and how it affects residents." She's demanding a government inquiry into why the council failed to evaporate leachate for three and a half years.
Wright offered a sobering long-term assessment: managing the leachate issues will take many decades. "Grandchildren of people living in this area will still have to deal with this," he said.
Why This Matters:
This isn't merely an environmental embarrassment—it's a case study in institutional failure and misaligned incentives. A regional council charged with managing critical waste infrastructure allowed conditions to deteriorate for years before taking action. The regulator had to step in and reject the council's own proposed solution as inadequate. Meanwhile, the risk to Perth's primary water source remains under-addressed by government bodies that should have prevented this situation decades ago. The 35-year operational history of an only partially-lined landfill sitting atop a critical aquifer represents a fundamental failure of planning oversight and environmental stewardship. Residents now face potential long-term groundwater contamination, methane hazards, and odor nuisance—all consequences of public sector mismanagement that private industry would face immediate litigation for causing. The council's belated acknowledgment that it can't even quantify its own liability suggests deeper governance problems that extend beyond this single facility.