Latest updates
Important information for communities around RAAF Base Darwin.
RAAF Base Darwin Community information session Factsheet – October 2024 (PDF, 1.64 MB)
RAAF Base Darwin Community information session Posters – October 2024 (PDF, 6.31 MB)
RAAF Base Darwin Community information session Presentation – October 2024 (PDF, 6.14 MB)
Investigations and findings
In November 2018, Defence completed initial 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 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 in 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 was found in soil or groundwater at levels that required further study or action:
- Former aircraft rescue and firefighting (ARFF) 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
- Wrapped stockpiles, also known as 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, The Northern Territory Environment Protection Authority has issued precautionary advice.
More detail on Defence’s risk assessments can be found in the Human Health Risk Assessment factsheet.
Additional investigations
Defence conducted a mass flux 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 remediation actions to reduce the amount of PFAS leaving RAAF Base Darwin.
At RAAF Base Darwin, PFAS was 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.
The following provides an update for each of the major PFAS source areas identified in the investigations:
Former fire training area 1
Investigations at the former fire training area 1 found the area was the largest source of PFAS at RAAF Base Darwin. The soil in this area contained approximately 34 kg of PFAS. A remediation action plan was prepared and implemented to reduce the ability for PFAS to move through groundwater, drains and creeks in this area.
Defence completed remediation works at this source area in November 2023 using a process called soil stabilisation. The process treated the PFAS impacted soils with activated carbon. This makes the PFAS stick to the product within the soil and stops it from moving when it rains. The treated soil was then placed back and covered with a clean layer of topsoil to prevent erosion.
Some of this treated soil was relocated to local landfills. Some soils with the highest concentrations of PFAS were sent interstate for disposal at a licenced thermal destruction facility. These works are reducing the amount of PFAS moving off the base. The area continues to be monitored as part of Defence’s ongoing monitoring program.
Current fire training area
Investigations at the current fire training area found this area contains approximately 11 kg of PFAS. A remediation action plan is currently being implemented to reduce the ability for PFAS to move from this PFAS source area into the management area.
Former aviation rescue firefighting station
Investigations at the former aviation rescue firefighting station found this area contains approximately 28 kg of PFAS. A remediation action plan is currently being developed to reduce the ability for PFAS to move through groundwater, drains and creeks into the management area.
Former fuel farms 4 and 6
Investigations at former fuel farms 4 and 6 found this area contains approximately 6.5 kg of PFAS. A remediation action plan is currently being implemented to reduce the ability for PFAS to move from this PFAS source area into the management area.
Hangar 31 and former fuel farm 1
Defence recently completed remediation works at Hangar 31 and former fuel farm 1. These works included removing the fuel tank and construction of new drains. These works removed approximately 90% of PFAS found in the source area. The area continues to be monitored as part of Defence’s ongoing monitoring program.
Former RAAF fire station and former fuel farm 5
A review of the investigation data found that the amount and movement of PFAS from the former RAAF fire station and former fuel farm 5 are low in comparison to other source areas. Management actions are minimising PFAS risks in this area.
Ongoing monitoring
Monitoring of PFAS continues 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.
Reports, presentations and factsheets
Detailed reports from the PFAS investigation and management 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.
Darwin Ongoing Monitoring Report 2023 - 2024 (PDF, 44.63 MB)
Darwin Ongoing Monitoring Report 2023 - 2024 Factsheet (PDF, 1.15 MB)
- PFAS Management Area Plan - Nov 2018 factsheet (PDF 921 KB)
- PFAS Management Area Plan - Jul 2019 report (PDF 9 MB)
- Human Health Risk Assessment Findings - Jun 2018 factsheet (PDF 1 MB)
- Human Health Risk Assessment - Jun 2018 report (PDF 809 KB)
- Ecological Risk Assessment Findings Nov 2018 factsheet (PDF 376 KB)
- Ecological Risk Assessment - Nov 2018 report (PDF 486 KB)
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, 735.58 KB)
Last review: 12 December 2024.