Department of Defence PFAS Remediation Soil Trials

Challenge

SLR was commissioned by CPB Contractors on behalf of The Department of Defence to undertake a bench scale per- and poly-fluoroalkyl substances (PFAS) remediation trial for soil.

SLR designed and led the remediation trial which involved blending different percentages of high grade activated carbon with PFAS impacted soil to immobilise the PFAS and limit the leaching potential. The objective of the trial was to provide The Department of Defence with a cost effective and sustainable approach to the management and onsite beneficial re-use of soil for construction purposes on base while reducing the volumes of waste to landfill.

Solution

Our team provided technical oversight for the trial which involved leaching the post treatment soils using United States Environmental Protection Agency Multiple Extraction Procedure, designed to simulate the leaching from repetitive precipitation. The repetitive extractions reveal the highest concentrations likely to leach in a natural environment.

Impact

The results of the trial indicated the percentage of leaching from soils was noted to decrease with an increase in powdered activated carbon (PAC) ratios with 3% PAC achieving the highest reduction. Immobilisation efficiency is directly related to the percentage of PAC added to the soil with 3% PAC demonstrating an efficiency of 526%. The client adopted 1% PAC treatment for 60,000 tons of PFAS impacted soil which resulted in a significant cost saving for The Department of Defence.