Swan River toxin claims disputed
Swan River toxin claims disputed

The Metropolitan Redevelopment Authority has contradicted claims by WA’s water watchdog that toxins from one of Perth’s most polluted sites are leaching into the Swan River.

In a report commissioned by the MRA and prepared by consultancy Greencap, the authority said a so-called containment cell above Mardalup Park in East Perth was working effectively.

The report flies in the face of research carried out by the Department of Water and its experts on behalf of the Swan River Trust which found the barrier was faulty.

The cell, consisting mainly of clay, was constructed in the 1990s as part of efforts to remediate the old East Perth gasworks site.

It was designed to prevent rainfall from topping up groundwater under Mardalup Park and overflowing into the Swan Estuary, which borders the site.

As reported in The Weekend West, the Trust report found the barrier had become “compromised” in places since being built in the 1990s.

The Trust also found the containment cell never fully covered the site, while not enough trees had been planted to keep groundwater levels suppressed.

This meant contaminated groundwater that was laced with toxins including hydrocarbons and heavy metals was likely to be leaching into the Swan, the report found.

“The direction of groundwater flow suggests offshore migration of this contaminated groundwater, despite attempts to contain it,” the Trust report notes.

“(This and other factors) supports the potential for contaminated groundwater at the gasworks site to be a current or recent contributor to the contamination that currently exists in the estuary.”

Although it did not respond to requests to provide a copy of the Greencap report, the MRA, which is responsible for the containment cell, cited the work to insist it was still working as intended.

MRA chief executive Kieran Kinsella said the report also showed no pollution from Mardalup Park had flowed into the Swan.

“Greencap environmental consultants were recently appointed by the MRA to undertake additional investigations including the testing of the quality of groundwater located both within and outside the containment cell as well as the river water,” he said.

“The results of these investigations confirm that the cell is operating effectively and that there are no traces of (hydrocarbons) in the water or evidence that contaminated groundwater or soil from within the cell is leaking into the Swan River.”

The West Australian

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