Evaluation of flow characteristics of a sand column using magnetic resonance imaging

Magnetic resonance imaging (MRI) was used to evaluate a column designed to conduct contaminant retardation tests on geological materials under saturated conditions. MRI procedures revealed sediment heterogeneities and preferential flow pathways inherent in the sediments as well as those created in the packing of the column. Sequential MRI images were also used to estimate tracer flow velocities and to detect density flows driven by density differences of as little as 0.0013 g/ml. Interpretation of the images emphasized the importance of small changes in hydraulic conductivity and of column orientation in experiments with fluids of different densities. MRI analysis during column flow experiments holds promise as a measurement technique to estimate retardation factors for selected solutes.