Advanced remedial methods for metals and radionuclides in vadose zone environments

The results of an integrated laboratory/intermediate-scale investigation using advanced geophysical techniques and natural marker monitoring to simulate, develop, demonstrate, and monitor foam-based delivery of remedial amendments to stabilize metals and radionuclides in vadose zone environments is presented. Two-dimensional flow cell systems were used to develop and optimize foam-based delivery technology. The flow cell was 100 cm long, 90 cm high, and 15 cm wide, and contained approximately 255 kg of sediment. The total and leachable concentrations of uranium indicated that the bulk of the uranium had remained within the original zone, suggesting potential in-situ stabilization. Time-Domain Reflectometer (TDR) and radar methods were used to measure electromagnetic wave propagation characteristics over the approximately 100- to 1000-MHz range at the laboratory and field scales, respectively. Introduction of remedial and delivery agents will likely cause short-term community changes that can be monitored and assessed concomitant with contaminant fate and transport.