Soil Vapor Diffusion at the Site of a Former Gas Station
This model calculates air concentrations of BTEX (benzene, toluene, ethylene and xylene) at the site of a former gas station which leaked fuel to the ground. The subsurface fuel is not moving, but it is supplying vapor which is diffusing up towards the ground surface. The model estimates vapor concentrations, by simulating vapor diffusion through the soil column in gas and water phases, in two locations: above the ground surface, and within a building that may be constructed on the site.
Measured soil-gas concentrations of BTEX compounds in the deep soil layer are assumed to be constant. This model calculates upwards diffusion through both soil gas and water phases to the foundation soil beneath the building using different effective tortuosity values for air phase and water phase diffusive fluxes.