The effects of preferential flow and soil texture on risk assessments of a NORM waste disposal site

作者：Pontedeiro E M; van Genuchten M Th^*; Cotta R M; Simunek J

来源：Journal of Hazardous Materials, 2010, 174(1-3): 648-655.

DOI：10.1016/j.jhazmat.2009.09.100

• Radionuclide transport
• NORM wastes
• Preferential flow
• Risk assessment
• Solid waste disposal

This paper investigates the environmental fate of radionuclide decay chains (specially the (238)U and (232)Th series) being released from a conventional mining installation processing ore containing natural occurring radioactive materials (NORMs). Contaminated waste at the site is being disposed off in an industrial landfill on top of a base of earth material to ensure integrity of the deposit over relatively long geologic times (thousands of years). Brazilian regulations, like those of many other countries, require a performance assessment of the disposal facility using a leaching and off-site transport scenario. We used for this purpose the HYDRUS-1D software package to predict long-term radionuclide transport vertically through both the landfill and the underlying unsaturated zone, and then laterally in groundwater. We assumed that a downgradient well intercepting groundwater was the only source of water for a resident farmer, and that all contaminated water from the well was somehow used in the biosphere. The risk assessment was carried out for both a best-case scenario assuming equilibrium transport in a fine-textured (clay) subsurface, and a worst-case scenario involving preferential flow through a more coarse-textured subsurface. Results show that preferential flow and soil texture both can have a major effect on the results, depending upon the specific radionuclide involved.

• 出版日期2010-2-15