Soil Solidification and Stabilisation

Soil materials from a Defence site in preparation for testing.

Typical leaching setup which involves multiple leaching events of the undisturbed monolith sample.

Typical equipment used for the structural integrity procedure.

Solidification

Soil solidification involves mixing a binding agent with affected soil to bind the compounds in a solid block, trapping them in place. Defence first conducted solidification trials in 2016. Initial results were favourable, however further analysis is required to determine its viability.

Stabilisation

Stabilisation involves mixing particular materials into affected soil to cause a chemical reaction, which will ensure PFAS is bound and unable to spread. The aim of stabilisation trials was to test stabilising PFAS in soil to limit further migrating in the environment.

2017 Soil Solidification and Stabilisation Trials

The Department of Defence - in collaboration with environmental consultants - undertook a soil solidification and stabilisation trial, in February 2017. The objective of the trial was to assess the effectiveness of nine individual products in chemically immobilising PFAS in soil.

A review of the trial identified a number of products which showed the potential to reduce the ability for PFAS to migrate away from the source soil. However, a number of questions surrounding the long-term effectiveness of the respective processes were raised by both Defence and the regulators; namely, changes in soil structure and biology as well as the effects these processes may have on plant life. As such, additional testing would be required prior to any recommendations being made.

In November 2017, Defence conducted a ‘Request for Information’ process, for soil remediation technologies, which did not identify any solutions which could be implemented in the field immediately. However, it was identified that the industry is continuing to mature and develop technologies which may be applicable in the future.