2017/19 – Army Aviation Centre Oakey (Queensland) – PFHxS, PFOS, PFAS

http://www.defence.gov.au/Environment/PFAS/Docs/Oakey/Reports/201907OakeyGME.pdf

The higher PFAS concentrations in groundwater beneath AACO are generally adjacent to the nine potential source area previously identified, consistent with the results of previous monitoring events. PFAS concentrations in a groundwater monitoring well (MW202) which is located down-hydraulic gradient of the former fire station had the highest PFAS concentrations reported at AACO (715 μg/L sum of PFHxS and PFOS). A groundwater treatment plant has been operational since 2017 and by June 2019 has treated 58 ML of groundwater from the former fire station area.It is noted that the sum of PFHxS and PFOS concentrations in MW204, located down-hydraulic gradient of the former fire station, were approximately 40% lower in April 2019 compared to the sum of PFHxS and PFOS concentration recorded in January 2018. This monitoring well has only been monitored on four occasions. The reduction may be associated with remediation operations in this area where groundwater is extracted for treatment. Future data from monitoring wells in this area will inform longer term trends in relation to changes in PFAS concentrations in groundwater as a result of the remediation…

Monitoring wells at AACO:· A total of 33 out of 34 groundwater samples collected from on-Site wells exceeded the adopted human health guideline value for drinking water for sum of PFHxS and PFOS. The maximum sum of PFHxS and PFOS concentration was 715 μg/L at MW202 located in Area B3 close to the former fire station.· A total of 17 groundwater samples collected from on-Site monitoring wells exceeded the adopted human health guideline value for drinking water for PFOA. The maximum PFOA concentration was 20.5 μg/L at MW202 in Area B3.· A total of 30 groundwater samples exceeded the adopted human health guideline value for recreational use for sum of PFHxS and PFOS. There were two exceedances of the adopted human health guideline value for recreational use for PFOA.· The PFOS guideline value for 99% level for the protection of freshwater species is 0.00023 μg/L which is below the limit of reporting, resulting in exceedance of this guideline value for all samples where PFOS was detected (total of 33 PFOS detections). Since the guideline value is above the limit of reporting, it is not possible to ascertain if the other groundwater sample exceeded the guideline value.· Two on-Site groundwater samples exceeded the PFOA ecological guideline value of 19 μg/L.These were from MW202 and MW204 located near the former fire station in Area B3

Monitoring wells and residential bores in MA· In Management Zone 1, 14 out of 15 groundwater samples exceeded the adopted human health guideline value for drinking water for sum of PFHxS and PFOS, with the maximum concentration detected at GW20 (47.4 μg/L). There was one exceedance of the adopted human health guideline value for recreational use for PFOA.

· In Zone 2, 16 out of 23 groundwater samples exceeded the adopted human health guideline value for drinking water for sum of PFHxS and PFOS, with the maximum concentration detected atGW21 (4.5 μg/L). There were no exceedances of the adopted guideline value for recreational use for PFOA.

· In Zone 3 and beyond, seven of the 34 groundwater samples exceeded the adopted human health guideline value for drinking water for sum of PFHxS and PFOS. The maximum concentration detected was 0.5 μg/L (bore not identified for privacy reasons). There were no exceedances of the adopted guideline value for recreational use for PFOA.· The PFOS guideline value for 99% level for the protection of freshwater species was exceeded in 45 groundwater samples. As the limit of reporting is greater than the PFOS guideline value, the there is the potential for other samples to also exceed the guideline value.· The PFOA guideline value for 99% level for the protection of freshwater species was not exceeded in the groundwater samples from the MA.