A subsurface line source of volatile organic compounds (VOCs) such as soil fumigants injected through a shank or applied through subsurface drip irrigation is subjected to transport in a two-dimensional domain perpendicular to the line source. Because a volatile chemical will have a significant portion in the vapor phase, its fate and transport in a porous media would simultaneously occur in both the gaseous and liquid phases. Adsorption and desorption with the solid phase or soil particles would make the transport process more transient. Temperature can also affect the transport parameters and processes, especially for the vapor phase diffusion and vapor to liquid phase partition. A mechanistic-type of modeling should consider all these process factors. The focus of this study was to model the two-dimensional lateral transport of a fumigant chemical and assess potential environmental impact on nearby water bodies. Specific objectives of this modeling effort were (1) to provide predicted environmental concentrations in a ditch 100-cm wide by 120-cm deep that is filled with 30-cm water and the ditch could be located at any horizontal distance from the field boundary, and (2) to determine the maximum VOC concentrations in the upper 30-cm soil profile beyond a threshold distance from the source. Results indicated that predicted cumulative total VOC concentrations in ditch water decreased rapidly with distance from the source. The concentration, cumulative up to 120 days after model run, decreased to very small values at more than 3 m from the source. The predicted instantaneous (every 5 cm increment) and 30-cm average total VOC soil concentrations (sum of liquid, vapor, and absorbed phases) also decreased rapidly with distance.