The Federal Government has started work to clean up the PFAS chemicals still leaking from the Tindal RAAF Base.
The Defence Department has begun installing the first of probably two water treatment plants at the base.
The plants will extract PFAS from the areas most contaminated, where the firefighting foams were used in training areas for 16 years from 1988.
Large scale soil remediation works have not started yet.
Defence, health and other government officials will be again briefing Katherine residents on PFAS at a meeting at Knotts Crossing on Monday.
Senior defence official, Steve Grzeskowiak, is again expected to lead the briefing.
Mr Grzeskowiak told a Senate hearing late last month the treatment plants will clean PFAS from groundwater, and then put the clean water back.
He told the hearing that defence would “need to run those plants for a long time”.
For an expected cost of $5 million for the first plant, it is expected to treat five million litres of water per day.
“On the base at Tindal we are installing the first of probably two water treatment plants that will start to draw water from the higher contaminated source area—the old firefighting training area,” Mr Grzeskowiak said.
“It will draw water from the ground, clean it and put it back. That's at the beginning of the remediation strategies for Tindal. That's going to be a long-term endeavour.”
He said defence had taken the “best advice we can from our experts in this field about where we should site those plants”.
“Intuitively, it will start to make a difference because, for every litre of water we take some PFAS out of, we are removing PFAS from the environment.
“We're not exactly sure how that will affect the flow of PFAS in the aquifer nearby. It will affect it in a positive way, in that there will be less contaminant in the ground.””
Katherine is still waiting for more information about its own town water treatment plant while it remains on water restrictions because of PFAS.
Power and Water officials want a big plant capable of cleaning PFAS from about 10 megalitres of contaminated water per day.