A new future for former aluminium smelter site with PFAS contamination

In 2020, Ramboll assisted our client with the demolition of a former aluminium smelter, and the characterisation and remediation of the land to be made suitable for future commercial or industrial land use.

The facility operated at the site in the Hunter Valley, NSW, Australia for over 40 years with multiple complex waste streams present, including PFAS contaminated soil from a former fire training ground. Other contamination issues included asbestos, fluoride and illegal waste dumping by others.

Ramboll undertook Phase I and Phase II contaminated site investigations of the former fire training ground, including soil, groundwater and surface water sampling of on-site and off-site receptors, preparation of a Remedial Action Plan, completion of remediation and validation works, ecological risk assessment, and identifying suitable options for remediation of per- and polyfluoroalkyl substances (PFAS) contaminated soil, including onsite treatment, onsite containment, offsite disposal and thermal destruction.

The client chose thermal destruction as the most effective way to remediate highly contaminated PFAS soil in the source zone and disposed of remaining PFAS impacted soil offsite. The project scope included consideration and mitigation of onsite and offsite ecological risks from PFAS contamination in a nearby ephemeral creek and man-made dams.

Technical expertise and stakeholder liaison

The scope of work included:

• Review of historical site information
• Sampling
• Analytical and quality planning
• Field investigation of soil, groundwater and surface water for PFAS, including total oxidisable precursor (TOP) assay
• Development of a PFAS-specific conceptual site model
• Sampling of onsite and offsite surface water receptors
• Ecological risk assessment
• In situ PFAS waste classification
• Remediation and validation of PFAS contaminated soil
• Liaison with a NSW EPA Accredited Site Auditor and NSW EPA.

Our client was looking to achieve complete remediation of their site without the need for long-term management into the future. It was important for Ramboll to adequately assess the site and understand the fate and transport of PFAS from the former fire training ground including a comprehensive assessment of soil, surface water both on-site and off-site and groundwater.

Remediation via source removal was the most suitable remedial option to meet our client’s objective and the works were completed efficiently to allow the broader remediation and divestment project to remain on track. This part of the site will be divested following the successful completion of our work.