Evaluation of mass flux to and from ground water using a vertical flux model (VFLUX): Application to the soil vacuum extraction closure problem

Site closure for soil vacuum extraction (SVE) application typically requires attainment of specified soil concentration standards based on the premise that mass flux from the vadose zone to groundwater does not result in levels exceeding maximum contaminant levels (MCL). However, realization of MCLs may not be attainable in many sites. A strategy based on the evaluation of site characterization, design, performance monitoring, rate-limited vapor transport, and mass flux to and from groundwater is discussed, focusing on the last component. A plant based on monitoring of three subsurface zones is presented and an analytical one-dimensional vertical flux model, called VFLUX is developed.