PFAS forensic source differentiation achieves 94% reduction in remediation liability

Overview

A newly published technical case study demonstrates how PFAS forensic source differentiation can dramatically reduce a landowner’s remediation liability. At a bulk petroleum storage facility in the United States, environmental consultants used advanced chemical fingerprinting techniques to distinguish site-derived PFAS contamination from off-site sources, ultimately reducing the client’s remediation footprint by 94 per cent. Published in Waste Advantage Magazine, the study provides a detailed methodology that is directly applicable to Australian contaminated sites where multiple potential PFAS sources complicate liability allocation and remediation planning.

Key details

The case study centred on a bulk petroleum storage facility where groundwater monitoring had detected PFAS contamination across a broad area. Without source differentiation, the site owner faced potential liability for remediating the entire plume. The consultants applied a forensic chemical fingerprinting approach with the following key elements:

• PFAS congener profiling: Rather than relying solely on total PFAS concentrations, the investigation analysed the specific ratios of individual PFAS compounds, particularly the relative proportions of perfluoroalkane sulfonic acids (PFSAs) and perfluorocarboxylic acids (PFCAs) across multiple groundwater monitoring wells.
• Source signature matching: Different PFAS sources produce distinct chemical fingerprints. Legacy aqueous film-forming foam (AFFF) formulations, for example, contain characteristic ratios of precursor compounds that differ from those found in landfill leachate, industrial discharges or atmospheric deposition. By comparing the congener profiles in groundwater against the known signatures of potential sources, the consultants could attribute contamination to specific origins.
• Fresh versus weathered AFFF signatures: The analysis distinguished between fresh AFFF signatures (indicating recent or ongoing release) and oxidised or weathered signatures (indicating historical contamination that has undergone environmental transformation). This temporal differentiation provided additional evidence for source attribution.
• Spatial delineation: By mapping the forensic data against the plume geometry, the consultants demonstrated that the majority of the PFAS plume originated from off-site sources. Only a discrete portion of the contamination was attributable to the client’s operations.
• Liability reduction: The forensic evidence supported a 94 per cent reduction in the client’s remediation footprint, with corresponding reductions in investigation, remediation and long-term monitoring costs.

Australian context

PFAS forensic source differentiation is highly relevant to the Australian contaminated land sector, where overlapping contamination plumes from multiple sources are common, particularly in industrial precincts, former defence sites and areas with historical firefighting training activities.

The Australian regulatory framework supports and, in many cases, necessitates this level of forensic investigation:

• NEPM 2013 Schedule B2: The National Environment Protection (Assessment of Site Contamination) Measure 2013 requires site characterisation to identify all potential sources and develop a robust Conceptual Site Model (CSM). Where multiple potential sources exist, the CSM must differentiate between on-site and off-site contributions to contamination.
• PFAS NEMP 3.0: The PFAS National Environmental Management Plan Version 3.0 provides guidance on source identification and liability allocation, recognising that PFAS contamination frequently crosses property boundaries and involves multiple responsible parties.
• State legislation: Regulatory clean-up notices issued under instruments such as the NSW Contaminated Land Management Act 1997, the Victorian Environment Protection Act 2017, or the Queensland Environmental Protection Act 1994 can impose broad remediation obligations on landowners. Without defensible forensic evidence, challenging the scope of such notices is extremely difficult.
• Cost recovery and apportionment: In multi-party contamination scenarios, forensic evidence is essential for cost recovery proceedings and for negotiating voluntary remediation agreements that fairly apportion liability.

Australian sites where this approach has direct application include RAAF Base Williamtown, where PFAS plumes from multiple historical AFFF use areas overlap with industrial and agricultural land uses, and numerous urban sites where former service stations, dry cleaners, and industrial premises have contributed to mixed contamination plumes.

Practical implications

For contaminated land practitioners, site auditors and legal professionals, this case study reinforces several critical practice points:

• Beyond total PFAS concentration: Basic PFAS concentration data (sum of PFOS and PFOA, or sum of 28 PFAS analytes) is insufficient for sites with multiple potential sources. Forensic congener profiling should be incorporated into investigation work plans from the outset where source differentiation is likely to be an issue.
• Conceptual Site Model quality: A CSM that does not address potential off-site PFAS sources is incomplete and may expose clients to unnecessary remediation liability. Desktop reviews should systematically identify all potential PFAS sources within and upgradient of the site.
• Laboratory capability: Forensic PFAS analysis requires laboratories capable of reporting a broad suite of PFAS analytes at low detection limits. Standard commercial PFAS panels may not provide sufficient congener resolution for forensic differentiation. Consultants should specify analytical suites that include precursor compounds and transformation products.
• Legal strategy alignment: Forensic source differentiation data should be collected and managed with the expectation that it may be used in legal proceedings. Chain of custody, quality assurance/quality control protocols and data interpretation must be defensible under cross-examination.
• Proactive investigation: Landowners and their consultants should not wait for a regulatory notice before investing in forensic source differentiation. Early identification of off-site contributions can inform negotiation strategies and reduce long-term liability exposure.

References and related sources

• Waste Advantage Magazine: Case study of a groundwater PFAS plume forensic source differentiation technique (primary source)
• NEPM 2013: National Environment Protection (Assessment of Site Contamination) Measure
• PFAS National Environmental Management Plan
• View the iEnvi LinkedIn post

How iEnvi can help

iEnvi’s contaminated land team has extensive experience in PFAS site investigation, forensic source differentiation and liability assessment. We design investigation programmes that go beyond standard compliance monitoring to provide the forensic evidence needed to accurately allocate remediation responsibility. Our remediation specialists develop cost-effective remediation strategies informed by robust source attribution, and our expert witness professionals provide defensible technical evidence in contaminated land disputes and cost recovery proceedings.

This is an iEnvi Machete news summary. Prepared by iEnvi to summarise the source article for contaminated land, groundwater, remediation, approvals and site risk professionals.

Need advice on this topic? Speak to an iEnvi expert at hello@ienvi.com.au or 1300 043 684, or contact us online.