Reactive Soil Mixes for Enhanced PFAS Adsorption in Stormwater Infiltration Basins: Mechanisms and Field Assessment

Abstract

Per- and polyfluoroalkyl substances PFAS have emerged as persistent contaminants of concern in urban stormwater systems due to their chemical stability, mobility, and resistance to conventional treatment processes. Stormwater infiltration basins, while effective for hydrologic control, may facilitate PFAS migration into subsurface environments if not properly engineered. This study investigates the effectiveness of reactive soil mixes incorporating biochar, zeolite, and iron oxide as amendment media for enhanced PFAS adsorption in stormwater infiltration basins. Laboratory-scale adsorption assessments were combined with field-scale demonstration and pre- and post-infiltration monitoring to evaluate retention performance and dominant adsorption mechanisms. Results indicate that blended reactive media significantly improve PFAS attenuation compared to native soils, with adsorption governed by a combination of electrostatic interactions, hydrophobic partitioning, and surface complexation. Field observations confirm sustained PFAS reduction under operational stormwater loading, supporting the integration of reactive soil amendments as a practical strategy for mitigating PFAS transport in infiltration-based stormwater management systems.