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HMAS Stirling PFAS Investigation Detailed Site Investigation FindingsPFAS Investigation and Management Program
Defending Australia and its National Interestswww.defence.gov.auMay 2018
About the InvestigationIn May 2017, Defence commenced a detailed environmental investigation to identify the nature and extent of per- and poly-fluoroalkyl substances (PFAS) on, and in the vicinity of, HMAS Stirling, Garden Island (the Base), as a result of the historical use of legacy firefighting foams at the Base.
The investigation is identifying whether the use of these foams has resulted in risks of exposure to humans or ecosystems, and will help develop strategies to minimise exposure, should these be required.
Investigation update The first stage of the investigation, the Preliminary Site Investigation, was completed with outcomes provided to the local community in July 2017.
The second stage of the investigation, the Detailed Site Investigation, commenced in July 2017 and was completed in April 2018. The Detailed Site Investigation involved sampling of soil, sediment, pore water, surface and ground water to collect information and better understand how PFAS moves through the environment.
A draft report, including the sampling results, has been prepared and the final report will be published in May 2018 at the following link:
http://www.defence.gov.au/Environment/PFAS/ Stirling/publications.asp
The third stage of the Investigation, the Ecological Risk Assessment (ERA), commenced in October 2017 and will be completed in mid 2018.
Overview• Primary soil, sediment, pore water, surface water
and six rounds of groundwater sampling completed.
• The Detailed Site Investigation report will be published in May 2018.
• ERA – Sampling and Analysis Quality Plan (SAQP) developed and endorsed by the Contaminated Sites Auditor.
• Biota sampling (sandworms, filter-feeders, seagrass and sea lettuce) to support the ERA commenced in March 2018 and was completed in April 2018.
• ERA to be delivered mid 2018.
• In the absence of a significant human exposure pathway there is currently no requirement to complete a Human Health Risk Assessment (HHRA).
In order to investigate these areas, the following sampling program was completed in accordance with the Contaminated Sites Auditor endorsed SAQP. See sampling table overleaf.
PFAS Source Areas
402
9
4556
4552
4551
Fire training area
InvestigationArea
HelicopterSupport Facility
Demolition Ground
AVCATStorage
WastewaterTreatment Plant
Fuel Farmand Infiltration Basin
DredgeSediments
Fire Station
Detailed Site Investigation Summary The initial phases of work identified potential PFAS Source Locations on Garden Island as presented in the figure below.
Soil and water sampling on Garden Island
HMAS Stirling PFAS Investigation Detailed Site Investigation FindingsPFAS Investigation and Management Program
Defending Australia and its National Interestswww.defence.gov.auMay 2018
Watertable
Lateralgroundwater
flow
Site users – exposure pathways– Soil ingestion/dermal contact (FTA only)– Dust inhalation of soil (FTA only)– Groundwater dermal contact (construction workers only)
Recreational users – Ingestion of aquatic organisms (to be assessed in ERA)
Source area – fire training area (FTA)– drainage swales– demolition ground– wastewater treatment plant– dredged sediments– helicopter support facility– fuel storage– firestation
Source areawaste water
treatment plantseepage ponds
Fresh groundwater
Saline groundwater
Groundwatermonitoring wells
Freshwater/saltwater interface
Vertical migrationof PFAS into groundwater
(recepter)
Vertical migrationof PFAS intogroundwater
(recepter)
Potential migration ofPFAS into saltwater
Groundwaterdischarge into
marine sediments
Seagrass/Benthic Habitats –Potential uptake of PFAS from
groundwater, sediments, and surfacewater(recepter)
(to be assessed in ERA)
Bioaccumulation andbiomagnification in the
marine foodchain(to be assessed in ERA)
Leederville Formation
Kardinya Shale (North)/Rockingham Sand (South)
Tamala Limestone
Safety Bay Sand
Indian Ocean Cockburn Sound
~20 - 27 MBGL
~35 - 37 MBGL
~154 - 157 MBGL
ERA: Ecological Risk Assessment
Not to scale
MBGL: Metres below ground level
HMAS Stirling – Revised Conceptual Site Model
HMAS Stirling PFAS Investigation Detailed Site Investigation FindingsPFAS Investigation and Management Program
Defending Australia and its National Interestswww.defence.gov.auMay 2018
Based on the findings of the DSI sampling program the PFAS exposure risk presented by the site is considered low because:
• Groundwater on Garden Island is not used for drinking, irrigation or recreational purposes.
• Soil contamination which presents a potential risk of PFAS exposure is limited to the base of a contained fire pit within the Fire Training Area.
The initial findings from the Detailed Site Investigation indicate the absence of a significant human health risk. This is because all water for potable use on Garden Island is brought in from the mainland. In the absence of a significant human exposure pathway there is currently no requirement to complete a HHRA. An ERA is currently underway and following completion of the ERA the requirement for a HHRA will be reassessed.
Potential risks have been identified to the local ecology in terms of:
• Leaching of PFAS from soils into the underlying groundwater.
• Migration of PFAS impacted groundwater into the local marine environment.
• Bioaccumulation and biomagnification within the food chain.
The risks to the local ecology will be assessed as part of an ERA.
Matrix
Total number of Samples Analysed
Total number of PFAS Detections
Total samples that exceed guidelines*
Soil 215 174 33
Groundwater 474 448 386
Surface Water 34 16 15
Sediment 36 15 1
Pore Water 27 11 10
*Water 99% Fresh and Marine Water Guideline: 0.00023 µg/L, Soil/ Sediment Ecological Guideline Value – Indirect Exposure: 0.14 mg/kg
Ecological Risk Assessment Based on the initial investigation findings, Defence commenced an ERA in October 2017. The aim of the ERA is to better understand potential risks of PFAS exposure to the environment.
• An ERA SAQP has been approved by the Contaminated Sites Auditor and reviewed by local regulators.
• Biota sampling to inform the ERA commenced in March 2018 and was completed in April 2018.
• Samples of sand worms, filter feeders, sea grass and sea lettuce will be analysed at an accredited laboratory.
• Contaminant fate and transport modelling was completed in April 2018.
The ERA will be completed in mid 2018. Findings from the ERA will be used to inform further management decisions.
HMAS Stirling PFAS Investigation Detailed Site Investigation FindingsPFAS Investigation and Management Program
Defending Australia and its National Interestswww.defence.gov.auMay 2018
Next stepsFollowing completion of the ERA, a PFAS Management Area Plan (PMAP) will be developed for HMAS Stirling and Garden Island. This document will identify areas of PFAS impact, and detail the management measures required to reduce the risks of exposure to PFAS in these areas including the requirement for remediation if appropriate.
Keeping the community informedDefence is committed to regularly updating the community throughout the investigation. As well as community information sessions, updates are provided through the project website, direct mail and factsheets as new information becomes available.
Useful LinksHealth Based Guidance Values:
http://www.health.gov.au/internet/main/publishing.nsf/content/ohp-pfas-hbgv.htm
Western Australia Department of Water and Environmental Regulation:
https://www.der.wa.gov.au/our-work/community-updates/416-pfas-investigations-in-western-australia
Cockburn Sound Management Council, PFAS Water Quality Sampling Fact Sheet:
https://www.der.wa.gov.au/images/documents/about/csmc/PFAS_Factsheet.pdf
Contact the HMAS Stirling Investigation Team
Media enquiries should be directed to Defence Media on (02) 6127 1999 or [email protected]
1800 852 160
http://defence.gov.au/environment/pfas/stirling/
RPS Australia West Pty Ltd, PO Box 170, West Perth, WA 6872
