In Canada, the sale of AFFF-containing PFOS &gt; 0.5 ppm was banned in 2008. Firefighting training areas at Canadian miltary bases were initially investigated for the presence of traditional contaminants, such as petroleum hydrocarbons and metals. However, recent changes to regulatory and environmental quality guidelines have required federal custodians to return to their sites and re-evaluate them for potential AFFF impacts, often after site remediation has taken place for other contaminants.This further complicates the evaluation of the environmental fate of certain perfluorinated and poly-fluorinated alkyl substances (PFAS; found in AFFF) which is already difficult, given their unique physical and chemical characteristics, and the additional complexities associated with synergistic and competitive interactions in an uncontrolled environment (such as a groundwater plume).Data gaps for contaminants of potential concern (including PFASs, petroleum hydrocarbons (PHCs) and metals) were identified from previous Environmental Site Assessments and Investigations (1986 – 2011). Field investigations and laboratory analysis of over 40 soil, groundwater, surface water and sediment samples was completed for PFASs and their co-contaminants in a well-characterized geological setting. Using the historical and current data, we demonstrate the effect of co-contaminant impacts and the importance of the hydrogeological setting on evaluating the fate and transport of twelve PFASs (PFUnA, PFPeA, PFOS, PFOSA, PFNA, PFOA, PFHxA, PHxS, PFHpA, PFDoA, PFDA, PFBA) in groundwater/surface-water systems. In particular, we note the presence and importance of a ‘smear zone’, associated with rising and falling water table elevations, and the identification of lateral and vertical pathways associated with co-contaminant migration. Fate and transport pathways are evaluated using chemical fingerprinting, geostatistical and, hydrogeological approaches. Results from this work may provide better guidance for site assessment and management practices for PFAS-impacted sites, and provide insights to appropriate remedial approaches and protection of drinking water aquifers and freshwater aquatic systems.

Investigating historical impacts of AFFF and co-contaminants

251st National Meeting (2016)

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