<p>The spill of petroleum-derived contaminants, commonly referred to non-aqueous phase liquids (NAPL), in the subsurface can generate widespread contamination throughout infiltration into the subsoil, and partitioning into one or more phases (gaseous, dissolved, free NAPL, residual NAPL, and entrapped NAPL). Since the movement of NAPL through the vadose zone and saturated zone involves various processes and is affected by many factors, numerical modeling of fate and transport of NAPL including the characteristics of the porous media, the properties of NAPL, as well as the estimation of spilled volume and its distribution in heterogeneous subsurface systems is very complex. Thus, in this study, numerical modeling of NAPL using lumped kinetic parameter approach representing the mean value over the representative elementary volume were evaluated for multicomponent components in NAPL. Modeling predictions with lumped kinetic parameter approach for multicomponent components were validated by comparing to those with literature kinetic parameter for single component. From the results, numerical modeling of NAPL using lumped kinetic parameter approach can predict the multicomponent fate and transport with minimum mass balance error in some cases. Those mass balance errors were clearly dependent on the composition and mole fractions of NAPL, and mass transfer for the soluble compounds under conditions of low NAPL saturation is rate-limited. However, numerical modeling of NAPL using lumped kinetic parameter approach can provide rough insight on fate and transport of multicomponent components in NAPL with reduced effort and time without the need of kinetic and interaction parameters of all components in NAPL.&#160;</p>
Analysis of vadose zone tritium transport from an underground storage tank release using numerical modeling and geostatistics