The environmental activist Erin Brockovich has welcomed a class action settlement over potentially hazardous chemicals used in firefighting foam at three Australian defence bases.

Shine Lawyers, which represents the actions at Oakey in Queensland and Katherine in the Northern Territory, said those affected were thrilled after a five-year wait for justice.

The agreement would compensate communities for extensive property value losses, said Shine’s Joshua Aylward.

Three federal court class actions have been launched over the PFAS chemicals (per-and polyfluoroalkyl substances) used in firefighting foam.

The third is related to contamination in Williamtown, New South Wales.

Brokovich said the settlement enabled affected communities to turn the page on a difficult chapter of their lives.

“I know better than most how gruelling and time-consuming class actions can be so I want to congratulate residents for never giving up hope,” she said.

Erin Brokovich has commented on the class action settlement over PFAS chemicals in Australia, saying ‘I want to congratulate residents for never giving up hope.’ Photograph: Jono Searle/EPA

Aylward said: “The people of Oakey and Katherine have been living in limbo for more than five years.

“We’re pleased to have achieved this outcome for these communities and to have helped affected property owners to move forward with their lives.”

The federal government said the parties were finalising detailed terms of the settlement. The terms are subject to federal court approval.

The government said it was committed to engaging with those affected by the contamination.

“Defence sees itself as part of the fabric of these communities,” the defence minister, Linda Reynolds, said in a joint statement with the defence personnel minister, Darren Chester.

“Reaching a settlement is not the end of Defence’s engagement in these communities, however, it does represent an important milestone on what has been a difficult journey for many people over the past few years.”

They said the government was committed to finishing environmental investigations into PFAS contamination around defence facilities, and to ongoing monitoring and engagement with communities.