Data tabled in parliament showed there were higher levels of groundwater contamination at off-site properties in Vasse than the former waste disposal facility.
It is understood the contamination started and an old unlined landfill on Rendezvous Road which spread to 18 residential properties nearby.
The affected residents were notified last year that it was no longer safe to use their bore water because of the contamination levels.
According to the Additional PFAS-impacted sites regulated under the Contaminated Sites Act 2003 there were a further 23 contaminated sites found in WA.
Most sites were former or are fire and rescue facilities, including the former Bunbury Career Fire and Rescue Service and the Bridgetown Volunteer Fire and Rescue Service Fire Station.
The data revealed levels in Vasse of perfluorooctane sulfonate (PFOS), perfluorooctanesulfonic acid (PFOA) and perfluorohexane sulfonic acid (PFHsX) were higher at the adjoining properties near the former waste disposal facility.
Groundwater contamination on the source site was found to be up to 0.0168 (ug/L) in PFOS, 0.023 in PFOA and 0.0284 in PFHxS levels.
Off-site the groundwater contamination levels were up to 0.35 (ug/L) in PFOS, 0.29 in PFOA and 0.62 in PFHxS.
A Department of Water and Environmental Regulation spokesperson said the concentrations at and near the former waste disposal facility were from a single monitoring event at select monitoring locations.
The spokesperson said the on-site monitoring wells tested meant they would not show the highest on-site concentrations because the wells were up hydraulic gradient (upstream) or cross gradient of the former landfill.
“By contrast, the off-site locations tested were immediately down hydraulic gradient (down-stream) of the former landfill,” the spokesperson said.
“Considering all available information (rather than the limited data in the answer) there was no evidence to suggest that contaminant concentrations generally were ‘intensifying’ at off-site locations.”
South West MLC Dr Steve Thomas said more information was needed on the immediate soil impacts from groundwater, which was a significant concern.
Dr Thomas said he expected more contaminated sites would be found all around WA making it a statewide issue and the government would have no choice but to come up with a statewide strategy.
“At this stage no level of government has developed a good long-term plan to manage this particular issue, all three levels of government will need to get together to come up with a plan,” he said.
The City of Busselton are currently investigating the situation and will be in a position to prepare a remediation plan after they complete this process, which is not likely to happen until mid 2019.
Sign up for our newsletter to stay up to date.