INVESTIGATING AMENDMENT DELIVERY MECHANISMS FOR IN SITU STABILIZATION OF STRONTIUM-90 IN POROUS AND FRACTURED MEDIA UNDERLYING A FIELD RESEARCH CENTER AT THE IDAHO NATIONAL LABORATORY

Remediation of radionuclides in deep porous and fractured media is a primary concern throughout the Department of Energy (DOE) complex. The most promising stabilization technologies include mineralization via biochemical amendments. Practical application of these amendments requires accurate site characterization, optimal delivery, and detailed process monitoring. There are a variety of biochemical amendments being investigated at the INL, and across the scientific community. However, capitalizing on these advances will require the ability to design, deliver, and monitor the processes. We present an experimental plan for investigating application and delivery mechanisms for Strontium-90 in situ stabilization in porous media interspersed between layers of fractured basalt underlying the Idaho National Laboratory (INL) near Idaho Falls, Idaho. Additionally, we will present results of initial site characterization during which subsurface monitoring captured infiltration from a nearby ephemeral river that flowed for ten days in June 2005. The recharge event provides insight into the formation, redistribution, and longevity of perched water zones that form in complex, heterogeneous vadose zones. The transport behavior captured during this recharge event demonstrates the inherent challenges associated with delivering contaminant stabilization amendments to target regions of the vadose zone at the INL. Data collected during the characterization event included traditional hydrological data such as water potential, water content, and perched water pressures, in addition to three-dimensional time-lapsed electrical resistivity tomography. The experimental plan outlines the use of a joint inversion methodology developed at INL for coupled data analysis.