In 1951, 6.7 liters of an aqueous acidic solution of irradiated uranium (360 GBq) leaked from a buried storage tank into unsaturated prairie soil, where it has remained, undisturbed. In October 2001, sonic drilling was conducted to recover core samples around and below the tank location. This paper describes the measurements and investigative approaches being pursued to determine the transport properties of the various fission and daughter products and actinides. Separate effects laboratory experiments are also being conducted involving both inert and radioactive samples in similar soil, to examine the effects on transport properties (diffusion and sorption) of temperature, recharge and discharge rates, concentration and soil porosity. Finally, transport modeling approaches are discussed.