Beginning in the 1990s, the issue of VOC vapor intrusion (i.e. the transport of VOC vapors from the subsurface into buildings through foundation cracks) began gaining regulatory attention.  Since then, our understanding of vapor intrusion fate and transport has been largely advanced through the use of computational models.  As part of this research, we solved a 3-D finite element model to evaluate the role of effective gas-phase diffusivity on vapor intrusion rates for a range of heterogeneous geologies. Our results show that the moisture-filled porosity (i.e. soil moisture) is an important variable due to its impact on the overall effective diffusivity.  In fact, when considering a site with numerous contaminants, the soil moisture content itself appears to play a more important role than does the exact value of the pure-air chemical diffusivity for a given chemical (or suite of chemicals).

Moisture-filled porosity as a key parameter for accurate prediction of vapor intrusion rates

244th National Meeting (2012)

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