A one-dimensional, steady-state model used to predict the concentration of contaminants migrating from a waste disposal facility via the subsurface, surface water, and air pathways to receptor sites. One module simulates the effects of precipitation, runoff, infiltration, evapotranspiration, barrier layers, and lateral drainage. Other modules simulate water saturation as a function of depth and simulate transient vertical transport in the unsaturated zone (taking into account longitudinal dispersion, linear adsorption, and first-order decay). A surface water module simulates surface stream contamination due to the complete interception of a steady-state saturated-zone plume. Air emission and atmospheric dispersion modules simulate the movement of chemicals into the atmosphere.