SEBS-amended in-situ mixed wall material for diesel-contaminated groundwater management

Diesel contamination in groundwater poses significant risks to environmental safety and human health, necessitating innovative containment solutions. A novel in-situ mixed wall material used in vertical barriers, composed of styrene-ethylene-butylene-styrene (SEBS)-amended bentonite slurry and aged diesel-contaminated sand, was proposed to mitigate the lateral migration of diesel in groundwater at industrial contaminated sites. Flexible-wall hydraulic conductivity test results revealed that SEBS amendment significantly reduced hydraulic conductivity to diesel (kdiesel), achieving an average kdiesel of 8.7 x 10-12 m/s at 25 % SEBS content (dry weight of bentonite), compared to 1.8 x 10- 8 m/s for unamended specimens. X-Ray micro-computed tomography (micro-CT) analyses demonstrated reduced pore channel connectivity, with the ratio of diesel-filled connected porosity to disconnected porosity decreasing from 3.0 to 0.6. The superior swelling, gelation, and diesel absorption properties of SEBS contributed to the enhanced hydraulic performance of the material. This research highlights the potential of SEBS-amended bentonite as an efficient alternative to conventional modifiers (organoclay) for managing non- aqueous phase liquid (NAPL) contamination in groundwater.