Contamination shock: Report warns of old Pasadena dump explosion danger

Residents living near a former dump in Adelaide’s south could be at risk of asphyxiation or exploding gas, a previously secret review warned.

Residents living near and on a former dump in Adelaide’s south could be at risk of asphyxiation or explosion from leaking gas, the state’s environmental watchdog has been told.

But Mitcham Council has sought to play down any dangers to human health from a historic landfill in Pasadena.

The council and Environment Protection Authority are investigating potential offsite contamination from the former dump which received council collected waste between 1959 and 1962 and was used as a private dump up until the late 1960s.

The large parcel of Pasadena land between the houses is the site of a former dump which is now centre of a major environmental investigation. Picture: Metromap

The majority of the 1.5ha site is owned by Hahndorf developer Warren Masters who paid $2.3m for his 1.4ha block at Port Lincoln Boulevard in 2008.

But he claims it would cost him at least $12m to rehabilitate his land and wants the council to buy the site and turn it into a park, claiming it should “clean up the mess”.

Two houses on neighbouring Quinton Court were also built within the footprint of the former of the dump in the late 1980s.

Work started this month to drill 15 groundwater wells and landfill gas bores to test for potential offsite groundwater and landfill gas contamination with investigations expected to take up to 12 months.

A map showing historic landfill gas bores. The green dots denote the most recent tests conducted in 2018.

It comes as Mr Masters obtained this month, through Freedom of Information, an independent review of the contamination status of the former landfill.

In an April 2020 report, Dr Ruth Keogh, principal environmental scientist for Fyfe, wrote there was potential risk to human health and groundwater from chemicals including cadmium, carbon dioxide and methane.

“Chemical substances (i.e. the landfill gases …) have been detected within the subsurface at concentrations above background and, despite its age, the landfill was still found to be producing these gases during recent monitoring events,” she wrote to EPA’s acting contamination manager Wendy Boyce.

“The presence of the chemical substances in those concentrations has resulted in potential harm to the health and safety of human beings that is not trivial taking into account the current or proposed land uses …”

She said the chemical substances were present “as a result of the historical landfill activities undertaken at the site”.

She wrote that residents 20m to the southwest of the landfill could be at risk with “respect to asphyxiation and/or explosion”.

Dr Keogh said 2018 testing of three wells in the southwestern corner of Mr Master’s site identified “elevated concentrations” of methane within an “explosive range”.

Warren Masters wants Mitcham Council to buy his portion of a former dump at Pasadena. He says it would cost him $12m to rehabilitate the property. Picture: Roy VanDerVegt

The council voted in confidence at its March 23 meeting against approaching Mr Masters “at this time” to buy his property.

The council’s chief executive Matthew Pears said that “to date” no risks to human health had been identified from the landfill.

“Once these (latest) investigations are completed, they will help to more fully understand the potential environmental issues so that appropriate management and remediation measures, if required, can be developed,” he said in a statement.

“If potential health risks are identified during the course of testing, these will be urgently and proactively addressed in collaboration with the EPA, SA Health and private land owners.”

An EPA spokeswoman said a voluntary site contamination assessment proposal was initiated in August 2019 to “understand any risks posed off-site by potentially impacted groundwater as well as landfill gas generation and migration”.

“The EPA needs to understand the results of the assessment to determine if any further assessment may be required by Mitcham Council, including if remediation is necessary to mitigate any off-site risks posed by the historic landfill,” she said.

“The responsibility for remediation arising from a change in use of the land would normally rest with the developer.”