THE Department of Defence (DoD) held a community walk-in session last week to update the community on its investigation into per- and poly-fluoroalkyl substances (PFAS) at and around RAAF Base Richmond.
Defence discussed the findings of the investigation and the recommendations of the PFAS Management Area Plan, with members of the Hawkesbury community.
Luke McLeod, Assistant Secretary PFAS Investigation and Management Program, told the Gazette that Defence is looking at "a couple of actions to reduce the source [of PFAS] at the [Richmond RAAF] base".
"In the absence of any technology that allows us to stop the migration, what we're looking at doing at Richmond - as we've been doing at other bases - is removing high concentration source areas which would otherwise be able to migrate."
Defence has been investigating the migration of PFAS into waterways and land around the RAAF base, after the chemical - which was used for a number of years for firefighting training on the base - contaminated the groundwater.
PFAS build-up in humans has been linked to cancer and other illnesses in the United States.
Mr McLeod said Defence wanted to keep the Hawkesbury community informed about its actions to "mitigate [PFAS] migration, and part of that included implementing an ongoing monitoring program" now that the investigation and risk assessments had been completed.
"Principally it's soil, typically from the former fire training areas. We know the concentration [of PFAS] in those source areas," he said.
"So we have two options. The first is to excavate, and dispose of the dirt in properly-licenced disposal facilities, and where we can't do that we will stockpile the dirt on base.
"The other option is to cap them, putting a non-permeable layer over the top of the source area which stops surface water interacting with that surface area and therefore stops PFAS chemicals being able to migrate into the surface water."
He said there were three PFAS source areas on the RAAF Base Richmond site, as well as one on the "northern portion of the site that is near Baker's Lagoon near where a sewerage treatment plant is located".
To work out which option they will use to stop migration of PFAS, Defence will continue doing research to understand the "lateral and vertical sense of the contamination and we need to work out what we need to dig up", Mr McLeod said.
He said the ongoing monitoring program will be implemented for an initial period of three years and would allow Defence to understand the extent to which PFAS continued to migrate off-site during that period.
"We will also judge whether excavation in the area will have an ongoing impact on migration," he said.
"We would expect to be continuously monitoring for PFAS as we monitor for a range of contaminants on site, ongoing.
"[There is] no end date [for monitoring] at this stage. We'll continue to do it until such time as we think the issue has been resolved."
Mr McLeod invited members of the community to engage with Defence about the effect PFAS might have on them via 1800 789 291, firstname.lastname@example.org or www.defence.gov.au/environment/pfas/Richmond.