2021: School Drive, Tomago “PFAS were detected in groundwater wells within and downgradient of the site, with much lower concentrations in the two upgradient wells, indicating the source of PFAS impact was historically on site.
The source is unknown, however JME considers it possible that PFAS was either previously used on site or was due to a previous bush fire. As no significant PFAS concentrations were detected in site soils, JME considered the primary source has been removed from site and groundwater concentrations of PFAS should naturally attenuate with time. Concentrations of PFAS compounds were generally below assessment criteria except for PFOS exceeding the 99% species protection ecological guideline value (which is very conservative, and based on the potential for PFOS to bioaccumulate or biomagnify), and the sum of PFOS and PFHxS exceeding the adopted DGV (drinking water) in MW4 in the second monitoring round.
JME notes that the site is within the Tomago Aluminium Company (TAC) buffer zone, which is a special environmental management zone defined in the TAC conditions of consent and derived from the ambient fluoride levels associated with TAC operations. Fluoride and aluminium concentrations in groundwater were highest in the upgradient wells and diminish with distance from TAC. JME considered aluminium to be the highest ecological risk to downgradient receptors.”