Consideration of Vadose Zone Moisture Dynamics in Remediation of PFAS-Impacted Soils

Oilfield brines are soluble, non-volatile, and recalcitrant contaminants that are vulnerable to capillary effects and evapoconcentration and have been known to recontaminate clean fill soils emplaced after excavations. This problem may also occur for some poly- and perfluoroalkyl substances (PFAS) at PFAS sites. In this paper, we consider the soil moisture characteristic curve, wetting front dynamics, and the moisture redistribution cycle to understand the potential behavior of different PFAS in the vadose zone. Drawing on experience with remediation of soils impacted by brine spills, we provide recommendations on the design and implementation of soil excavation and cover remedies such as capillary barriers to prevent recontamination.