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°ÄÃÅÐþ»úͼ has supported the Department of Defence to complete detailed investigations of potential PFAS contamination at HMAS Stirling in Western Australia.

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Challenge

As a result of the historic use of fire-fighting foams containing per- and poly-fluoroalkyl substances (PFAS), the Department of Defence has initiated a nationwide program to review, investigate and comprehensively manage the impacts of PFAS on, and around Australian military bases.

One such site is HMAS Stirling located on Garden Island, WA, where environmental investigations were undertaken by our contamination, environment and water teams, with program coordination by our specialist environmental remediation project management team and community engagement by our major project communications team.Ìý

At HMAS Stirling, completion of the investigation was required within a 12-month timeframe and all works were undertaken to meet the requirements of National Environment Protection Measure (NEPM) 2013 and the PFAS National Environmental Management Plan (PFAS NEMP).

Solution

°ÄÃÅÐþ»úͼ undertook a Detailed Site Investigation (DSI) to evaluate contamination at HMAS Stirling, with initial phases of work including:

• A data gap analysis
• A Sampling and Analysis Quality Plan (SAQP)
• Detailed Site Investigation (DSI)
• Six-month groundwater monitoring program
• Preliminary Human Health and Ecological Risk Assessment
• Community consultation and subcontractor management in line with relevant legislative and policy compliance requirements.

Subsequent phases of work involved delivery of a contaminant fate and transport model and the completion of a Tier 2 Ecological Risk Assessment (ERA) including biota sampling, to determine risks to Garden Island’s ecology and the surrounding marine environment.ÌýÌý

To meet tight timeframes for delivery, °ÄÃÅÐþ»úͼ employed multiple drilling and sample collection teams to operate across the Island concurrently. This reduced the amount of time required for each mobilisation and helped the project to remain on schedule.

Through detailed risk assessment and informed by the latest emerging contaminant science, our team was able to confirm that the use of PFAS on the Island had resulted in a very limited impact, presenting no risk to human health and very limited risk to local ecological communities. Ìý

Understanding that emerging contamination issues are of concern to communities but aren’t always well understood, our environmental and communication teams worked together with Defence to ensure complex investigation data could be presented to stakeholders in an accessible, easy-to-understand manner through presentations, walk-in events and one-on-one Q&A sessions.

Evidence-based response

Based on the detailed assessments and studies conducted by °ÄÃÅÐþ»úͼ, a determination was made that a remediation program would not be required at HMAS Stirling.

Understanding that data is vital to our efforts to effectively manage emerging contaminants like PFAS, our team designed a site-specific program to confirm the findings of the initial investigation through comprehensive monitoring and sampling over a two-year period.

The results of all investigations have been presented to the local community in sessions facilitated by our communications and engagement team.

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