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Important information for communities around RAAF Base Darwin.

Investigations and findings

In November 2018, Defence completed detailed investigations into per- and poly-fluoroalkyl substances (PFAS) contamination on and around RAAF Base Darwin. Defence recognises that PFAS contamination from RAAF Base Darwin is a significant issue for the local community. Defence is committed to working with other Commonwealth agencies and the Northern Territory Government to manage, remediate and monitor PFAS contamination in the area.

The investigations found that PFAS are mostly concentrated in areas where firefighting foams were previously used, stored or disposed. These are called source areas. PFAS at these locations can be found in soil and in water flowing through the source areas. PFAS moves in surface water flowing through drains and creeks or groundwater that flows underground through soil and rock.

Eleven source areas were identified on the base where PFAS were found in soil or groundwater at levels that required further study or action:

  • former aircraft rescue and firefighting fire station
  • current fire training area
  • former fire training area 1
  • former fire training area 2
  • former fuel farm 1
  • former fuel farm 4
  • former fuel farm 5
  • former fuel farm 6
  • hangar 31
  • aqueous film forming foam contaminated soil stockpiles
  • former aviation rescue firefighting station.

Human Health Risk Assessment

As part of the investigations, Defence conducted a Human Health Risk Assessment. This assessment measured the PFAS exposure risks to people living, working and undertaking recreational activities within the management area.

The assessment found a low risk for the majority of common activities and scenarios assessed. However, to support communities reduce their exposure to PFAS, the Northern Territory Environment Protection Authority has issued precautionary advice. More details on Defence’s risk assessments can be found in the Human Health Risk Assessment factsheet under the recent reports and factsheets section.

Additional investigations

Defence conducted a PFAS movement assessment that tracks how and where PFAS are moving from source areas and how much PFAS are leaving the base. This study helps determine the best management and remediation actions to reduce the amount of PFAS leaving RAAF Base Darwin.

At RAAF Base Darwin, PFAS were found to be primarily moving through surface water.

Groundwater discharge to Rapid Creek also contributes to some of the PFAS moving off base. To prevent PFAS moving from the source areas on base, the remedial works focus on treating PFAS in soils and other surfaces such as concrete.

Remediation and management

The aim of remediation is to minimise PFAS leaving the base by focusing on the remediation and management of the source areas. Over time this will contribute to the reduction of PFAS in the management area. Defence has a PFAS Management Area Plan setting out the proposed remedial works and other management actions to manage potential risks presented by PFAS.

Remediation actions to address the major PFAS source areas at RAAF Base Darwin are now complete.

At the majority of the major source areas, Defence undertook remedial works using a process called soil stabilisation. This involved mixing activated carbon with PFAS impacted soil. This causes the PFAS to bind to the carbon and prevents it from moving during rainfall. The treated soil was returned to the source areas and covered with a clean topsoil layer to protect it from erosion. Soil with the highest PFAS concentrations was transported and disposed at a licensed facility.

Remediation at some source areas included removal of the fuel tank and construction of new drainage infrastructure.

Overall, the remediation works are significantly reducing the amount of PFAS leaving the base. PFAS contamination at these source areas is monitored under Defence’s Ongoing Monitoring Program. Investigations also found that low concentrations of PFAS are moving from some minor source areas. Existing management actions are effectively minimising risks in these areas, and no remediation is planned at this time.

Ongoing monitoring

Defence routinely monitors PFAS on and around RAAF Base Darwin through sampling of surface water and groundwater, and fish, shellfish and crustaceans. Monitoring helps Defence understand if PFAS contamination is changing over time.

The results are published in an Ongoing Monitoring Report and factsheet. Defence will inform the community if changes to the management approach are required.

Monitoring results to date have found no significant changes to how PFAS are moving in the management area. The remedial works are expected to reduce PFAS from leaving the base, and over time this will contribute to the reduction of PFAS in the management area.

Recent reports and factsheets

Detailed reports from the PFAS Investigation and Management Program are available for download. Appendices to these reports can be found in the document archive. To discuss these reports, contact pfas.enquiry@defence.gov.au.

Document archive

The RAAF Base Darwin document archive contains information that Defence has published about the management of PFAS, including older community presentations, investigation reports, risk assessments and factsheets.

Some archived information has been superseded by recent reports and factsheets.

Documents Archive - Darwin (PDF, 352.15 KB)

Last review: 31 August 2025