Tamala Park Waste Facility in Perth’s northern suburbs is sitting on a massive buildup of leachate, and Western Australia’s Department of Water and Environmental Regulation has hit the Mindarie Regional Council with an Environmental Protection Notice over the site. The liquid from rotting rubbish has piled up under a landfill that has taken household waste from 800,000 Perth homes for 35 years, and the mess is now threatening the council’s closure plans around 2028.
Who Pays for the Dump
The people at the bottom of this arrangement are the ones living near the tip, while the council and regulator trade notices, assessments and technical language. As of October 2024, data showed 167 Olympic-sized swimming pools worth of leachate sitting at the bottom of the landfill. Without removal methods in place, that number was expected to rise. That’s not a small leak. It’s a buried flood of decomposing waste, left to fester under a system built to keep the city’s trash out of sight.
The landfill opened in 1991 and is run by the Mindarie Regional Council, which is made up of seven local governments. The site was expected to reach the end of its operational life around 2028, but the excessive buildup of liquid waste is now threatening those closure plans. The Department of Water and Environmental Regulation issued the notice on August 3, requiring the council to provide a detailed and accurate determination of the leachate levels and a leachate removal plan within 30 days. It also ordered improved landfill gas management, updated landfill closure planning and additional technical investigations.
What the Experts Said
Western Sydney University science professor Ian Wright, who said he has been a water scientist for 30 years, described leachate as the liquid often seen at the bottom of household bins. He said: “Leachate is the liquid that builds up in rotting rubbish. So a lot of people might have seen it if your garbage bin with lots of food and kitchen scraps has been left in the house, and you perhaps went away for a few days.” He added: “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.”
Wright said the 167 Olympic pools worth of leachate was a significant amount to be accumulated at the bottom of any tip and that it was “a major issue” for groundwater health. He said he was “very surprised” the landfill hadn’t been fully lined to prevent groundwater contamination of the nearby Gnangara aquifer, which provides almost half of all the water used in the Perth metropolitan area each year. He said: “As soon as I heard about this case study, my mind went straight to: could this be in any way a threat or a risk to Perth’s groundwater? Because the Gnangara sand aquifer is right on the edge of this area.” He also said: “It’s easy for waste from something like this landfill to move through sand down to the aquifer, so as to contaminate the groundwater.”
The landfill is only partially lined, and the Mindarie Regional Council’s recent request to install a piggyback liner and create a leachate management area in the northern portion of the tip, closest to nearby residential homes, was rejected by DWER at the beginning of August. A DWER spokesperson said highly elevated leachate levels were a significant consideration during the assessment. The spokesperson said: “Following detailed technical assessment, DWER concluded that the proposed works would generate additional leachate and would not adequately address the existing leachate, odour and groundwater issues at the site.” The regulator also said there are ongoing investigations into groundwater contamination at the site, but that there is currently a “low” risk to human health and the broader environment.
What Residents Want
Resident Mary O’Byrne, who has been campaigning against the odour and environmental concerns at Tamala Park Waste Facility, said: “My concern is the groundwater, what’s happening to that, and how it affects residents.” She also said: “I want a government inquiry into how this place is run. I want to know why, for three and a half years, they didn’t evaporate the leachate.” That demand lands in the middle of a system where the council says it’s managing the site, the regulator says it’s watching it, and the people living nearby are left to deal with the stink, the risk and the uncertainty.
Wright said he felt the council was trying to do its best to mitigate problems that likely began long before most councillors were in their roles. A spokesperson for the Mindarie Regional Council said it was taking the management of the landfill and the protection of the surrounding environment “extremely seriously.” The spokesperson said: “Elevated levels of leachate within the landfill is an issue that both MRC and the regulator have been aware of for some time. We share DWER’s concerns on this matter and are committed to finding a viable and lasting solution.” The spokesperson said the council had presented the information to the regulator voluntarily and had worked with the department for several years to monitor and manage the site’s environmental risks and to ensure the landfill could be safely and successfully rehabilitated.
The council said it couldn’t quantify the amount of leachate contained within the landfill and that this was a focus of its work in the coming months. It said: “We continue to deploy measures on site to control the amount of leachate generated, to prioritise the capping of open landfill areas, and to optimise odour management.” Wright warned that it would take many decades to manage the leachate issues on the site. “Grandchildren of people living in this area will still have to deal with this,” he said. The landfill’s buried waste keeps working long after the officials move on.