Harold E Holt Naval Communications Station site soil investigation

Client Name
Georgiou Group
Exmouth, Western Australia, Australia


SLR were engaged by Georgiou Group to undertake a soil investigation at the the Harold E Holt Naval Communications Station in Exmouth as part of the Deep Space Advanced Radar Capability (DARC) Project. The purpose of the soil investigation was to determine the contamination status of soils with areas proposed for excavation within the construction footprint and inform the potential for onsite beneficial re-use or offsite disposal. It was determined that soils within the project footprint were impacted by PFAS due to legacy fire training. Due to the levels of PFAS in the soil, offsite disposal to landfill was cost prohibitive due to the distance (1,600 km) to the only landfill in WA that could accept the material. In accordance with Defence PFAS Framework, re-use of PFAS impacted soils at the concentrations reported could only be undertaken if supported by a detailed risk assessment considering risks to human health and the environment.


Georgiou and SLR developed a design solution to beneficially re-use the material in another part of the site to achieve the required design levels. The design solution involved capping the material in-situ with clean material and a geotextile membrane to limit infiltration through the soil profile from surface and subsequent leaching to groundwater. SLR completed a source -pathway -receptor analysis and a tier 1 PFAS Risk assessment including calculating the PFAS Mass in the soil to be excavated and soils in the receiving area to evaluate potential risks to human health and the environment. Based on the risk assessment undertaken, the re-use of surplus PFAS impacted soil was not expected to adversely impact on the environmental or human health risk profile provided that the risk management actions and recommendations developed by SLR are implemented in accordance with the design solution.


The PFAS risk assessment was approved by Defence PFAS branch and SLR provided a cost effective (saving Defence $0.5M) and sustainable (avoiding disposal to landfill) solution to allow the beneficial onsite re-use of the material within the project footprint to achieve the desired design levels.