Modeling Contaminant Transport in a Large-Scale Groundwater Tank with Media Heterogeneity

A state-of-the-art physical groundwater flow and transport model was developed. The physical model consists of a large tank (approximately 10' x 14' x 8') filled with six feet of layered sand and silt media, and a fine sand lens within one layer. A dense, three-dimensional sampling matrix consisting of 105 time domain reflectometry (TDR) probes, pressure transducers, and thermocouples was multiplexed and connected to a data acquisition system. In addition, 105 sampling tubes and 84 screened-wells for pumping were located within the tank. One of the primary objectives of this research was to characterize flow and transport within the tank, determine characteristics of media packing, and system performance. K-field determinations from slug and tracer tests, including kriged K-fields from tracer tests, were performed. A nonpoint-source tracer test was used to calibrate a physics-based flow and a transport model (MODFLOW 2000 and MT3DMS). The calibrated model can now be applied to other studies at UVM or in collaboration with interested researchers.