This research was initiated in response to the establishment of an Independent Expert Panel at the Williamtown RAAF base following the acknowledgement that PFAS chemicals were recorded across the air force base as well as at off-base locations. The research focused on developing a Conceptual Site Model with limited understanding of the pollutants distribution but with the aim of ensuring that the investigation area would encompass all of the potentially impacted community and associated risks. The establishment of the Conceptual Site Model was hampered by complex surface and groundwater interactions across the region.
A detailed knowledge review was undertaken to examine the migration potential of PFAS contaminants across the Williamtown and Salt Ash region. This was supported by local understanding of the aquifer properties and selected field investigations to highlight the role of surface and groundwater interactions. This method resulted in the establishment of detailed investigation area risk maps.
A range of historic data was available to integrate with international reports on PFAS chemical properties to estimate transport rates and risk factors. The resultant risk maps are currently in the process of being validated by extensive field work campaigns.
The development of an independent expert group with a broad understanding of various hydro-geochemical processes has led to the establishment of an investigation area risk map and Conceptual Site Model for the Williamtown and Salt Ash area. This has guided extensive on-ground investigations and appears well supported by preliminary field data. The unique influence of gaining and losing flood mitigation drains has been critical in understanding risk across the large area. Future locations with emergent pollutants may benefit from the established approach undertaken at this site.