Ground Truthing a PFAS Model

Aslan Perwick, Nerena Rhodes, James Conway, Alan Pattle  - (Pattle Delamore Partners Ltd)

Understanding the fate and transport of PFAS in affected groundwater aquifers is
fundamental to managing the risk associated with these contaminant plumes.
Pattle Delamore Partners Ltd has been involved in an ongoing assessment of the
(likely) future behaviour of an existing, large scale PFAS groundwater plume. The
initial project objectives were to predict, as far as reasonably practical, the existing
extent and concentration distribution of the plume, and how the plume could
evolve in the short to long-term future. Quantitative 3D numerical groundwater
flow modelling (MODFLOW) and contaminant transport modelling (MT3DMS) was
utilised to assist with these complex predictions.
The project has now moved into a validation phase. Additional drilling and
groundwater monitoring has addressed areas of the aquifer/hydrological system
with previous knowledge gaps, which posed key uncertainties for the regional
groundwater resource. The additional data has provided a basis for further
validation of the conceptual model, and the predictions of the plume and it’s likely
future behaviour. This paper will cover the relevant history of the plume, the
original plume predictions, as well as presenting results and interpretations from
the recent gap filling and validation work .e.g. have we got it ‘right’ so far?, what
are the ongoing risks?