Sharp Interface Modeling of LNAPL Spreading and Migration on the Water Table

A common problem associated with subsurface contamination is the leaking of light nonaqueous phase liquids (LNAPLs) such as gasoline from underground storage tanks and other facilities. A model developed by Corapcioglu et al. (1996) to describe LNAPL transport on the water table was solved numerically, by accounting for residual NAPL retained by capillary forces. The model was exercised to simulate LNAPL mound formation and migration of an established mound. The results show that the ambient groundwater velocity has major effects on both the formation and migration of LNAPL mounds, although the degree of residual saturation affected only migration. Model results provide distributions of the NAPL phase and contaminated soil. The model and the solution method developed in this study can be used as a screening tool to assess the impact of NAPL contamination and to estimate remediation costs.