"May 1994." "RG-91."

Introduction to risk assessment for leaking storage tank sites -- Contaminant distribution in soils -- Bulk movement of hydrocarbons in soil -- Contaminant concentration in the unsaturated zone -- Equilibrium relations between the phases -- Estimating contaminant mass in soil -- Relevant fate and transport models -- Processes simulated by fate and transport models -- Advection -- Molecular diffusion -- Mechanical dispersion -- Hydrodynamic dispersion -- Sorption -- Biochemical transformations -- Analytical models -- Numerical models -- Available models -- Process of model application -- Typical data required by models. Appendices: The Sesoil model -- Jury's unsaturated zone model -- Analytical transport: one, two and three dimensional (AT123D) model -- The Summers model -- Bioplume II model -- Domenico's model -- Thibodeaux-hwang model -- Farmer's vapor emission model -- The Box model -- Gaussian dispersion model -- Examples of estimation of mass transport due to different transport mechanisms -- Conversion table.