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“Experts estimate there is more than four tonnes of PFAS sludge contaminating the groundwater and soils in the Katherine region.
The information was contained in a little heralded supplementary investigation report released on September 24.
Consultants to the Department of Defence confirmed in this updated report the majority of PFAS is transported off the Tindal RAAF Base by PFAS impacted groundwater.
‘A small percentage of this is directly from surface water run-off from drains on RAAF Base Tindal,’ the report says.
The PFAS contamination through the Katherine investigation area was estimated to be more than 3000 kilograms, the consultants said.
‘A further 1000kg of PFAS is potentially accessible for removal from the key source areas on RAAF Base Tindal.
‘Removing this residual mass will significantly reduce the ongoing leaching from the base and shorten the time for PFAS to flush from the environment.
‘The removal of PFAS from the source areas is unlikely to have a short-term impact on the concentrations of PFAS in groundwater and the Katherine River.’
The report also suggests 100kg of PFAS may be leaching from the base each year.
‘The estimate of dispersed mass in the system (3500 kg) is also similar to the mass that would be estimated based on 30 years since the start of source release at a flux of 100 kg/year leaving the Base.’ ”