VOC emission fluxes as a function of lateral distance from the source

Abstract

AbstractThere has been a great deal of recent interest in evaluating the potential for vapor transport from subsurface contamination into nearby buildings. There does not exist, however, any method for calculating whether buildings that are not directly over the source of contamination may be impacted. For simplicity, typical modeling approaches for estimating vapor migration through soil into buildings assume that the contaminated plume or soil lies directly underneath the building. The models do not take into account the lateral distance, if any, between the source of VOC emissions and the indoor space. This paper presents an approach to calculate diffusion‐limited emission fluxes as a function of lateral distance and evaluates the significance of these emissions over relatively short lateral distances from the source. A theoretical, mathematical approach was used. The results show that soil‐gas concentration and emission flux are both a decreasing exponential function of the lateral distance from the edge of the contaminant plume. Based on our calculations, the emission flux and the soil‐gas concentration are insignificant within a relatively short lateral distance from the source (e.g., 30 m). © 2004 American Institute of Chemical Engineers Environ Prog, 23: 52–58, 2004