In a couple of weeks scores of half-size shipping containers filled with tonnes of toxic soil will begin making the 3,500-kilometre journey from northern Australia to Victoria.
Defence has begun tackling the toxic legacy of the firefighting foam that was used for decades at the Tindal Royal Australian Air Force Base and other sites around Australia.
It has been more than six years since residents in Katherine were told that persistently high levels of toxic compounds, known collectively as perfluoroalkyl and polyfluoroalkyl substances, PFAS, had been found in their only drinking source.
Every year since, roughly 40 kilograms of the chemical has leached into the groundwater from the RAAF base, where large areas of contaminated soil have been left to seep.
Defence has conceded there is "no silver bullet" that would effectively destroy all traces of the "forever chemical" from the base, but it is committed to solving the problem.
"It's a complex chemical and it's a very complex remedial challenge," Defence's remediation advisor Amanda Lee said.
"What we've done here today is come up with the best solution available to us today with proven technology to try and address this problem."
Despite explicit warnings dating back to 1987 that the product must not enter the environment, many thousands of litres of the firefighting foam were discarded onto bare earth or washed into stormwater systems and evaporation ponds.
'Big reduction in mass'
Now two large areas at Tindal, where RAAF firefighters would wash their equipment and where firefighting foams were used in practice scenarios, have been identified as high priority for remediation.
This week the massive effort to dig up the estimated 60,000 tonnes of contaminated soil and crushed concrete from the two areas began.
Over the next few weeks, a series of logistical steps, including testing the contamination levels at laboratories, will see the earth set on two different paths.
About 13,500 tonnes of highly-contaminated soil is expected to be taken to Melbourne in sealed containers to be incinerated.
At the old fire training area, levels of PFAS were recorded as high as 500 milligrams per kilogram.
The rest, with PFAS readings between 1mg and 7mg per kg, will be remediated on the base with powdered activated carbon and put back into the ground or buried in old evaporation sites and capped.
Ms Lee says activated carbon essentially binds with PFAS and reduces the amount that can leach out.
"The fire training ground and the fire station, they contribute the biggest amount of mass that leaves the base," she said.
"With the soils being locked up with the stabilising material, it's going to reduce significantly, straight away.
"We expect to see a big reduction in the mass that's leaving the base this coming wet season."
Ms Lee said it had taken a number of years for Defence to gather enough information to address the chemical contamination, and more sites would need to be remediated in the near future.
'Poisoned the waterhole'
More than a year since a landmark class action suing the Australian government for allowing PFAS chemicals to escape Defence bases, many residents are still grappling with the challenges of living with contamination.
Peter John Spafford was Katherine's GP for over a decade and is troubled by the fact that "the polluter is cleaning up the problem".
"We know PFAS was already seeped into the system — it's already leached out," he said.
"So taking a small quantity that's probably remaining there and exporting it is really not cleaning up the problem at all.
"It is a minuscule part of the amount that has already escaped into the environment to which [Defence is] doing very little about.
"It's called the forever chemical and the problem is here in Katherine."
He said despite compensation finally reaching affected families last year, Defence should have bought back a lot of the land.
"We should be sitting here on free land, free water, because they poisoned the waterhole — it's as simple as that," he said.
"My patients came in more and more concerned about the fact that the banks wouldn't provide them with loans to expand their businesses, that they had moved to Katherine to escape from pollution elsewhere, had bought a bore property with pristine water coming out of the ground, and had effectively poisoned their children."
Resident Samantha Phelan said Defence's attempt to clean up PFAS pollution from its military bases was encouraging, but in her eyes too much time had passed for it to be commended.
"We are now in our sixth year — we still don't have a water treatment plant," she said.
"It is not good enough spending six years trying to work out what you're going to do with a problem.
"Our town, as is Oakey and Williamtown, are being used as experiments for how to get rid of PFAS from an aquifer and from soil."
Dr Phelan said since the contamination was first discovered many residents felt they had been kept in the dark.
"There's been no transparency … but everyone in this town has realised this is a forever chemical, and if we want to live in this town, we're kind of stuck with it," she said.
"We hope that the consequences for our kids aren't too bad — we cross our fingers and keep on rolling."
