The model presented in the study describes solute transport in soil columns by considering aggregate size distribution. An iterative numerical scheme is introduced to implement the model. The work clearly demonstrates the importance of including increasingly more detail in modeling solute-soil interactions and suggests that for certain spherical packing material sites, previous analyses of packed beds that ignore aggregate size distribution may be inadequate. Failure to include effects of aggregate size can lead to substantially different breakthrough curves and may incorrectly represent solute movement in contaminated soils or treatment systems.