GEOCHEMICAL REACTIVE MODELING OF FLOW AND TRANSPORT PROCESS AT A MINE SITE IN NORTHERN TERRITORY, AUSTRALIA

Abstract

Subsurface contamination of metals and radionuclides are common problems in abandoned
mine sites. Metals and radionuclides are likely to occur in the mobile phase or may bind to soil particles and
geologic framework. The transport process for reactive contaminants also include chemical reactions in
groundwater aquifers, which are complex physical and biogeochemical processes. Accurate tools to reliably
predict the movement and changes in concentration of metals and their daughter products (radionuclides)
formations in the subsurface environment is important for decision makers to analyze impact, and to evaluate
the effectiveness of remediation strategies. An advanced numerical model can provide such useful direction
of predictions. A 3-D contaminant transport model for fluid flow, hydrogeologic transport, and
biogeochemical kinetic and equilibrium reactions in saturated and unsaturated media was calibrated,
validated and implemented to model the hydrogeochemical processes that occur in the subsurface at such a
complex contaminated site, consisting of waste rock dumps and flooded mine pits of this abandoned uranium
mine site. The developed flow and transport simulation model for no longer in use mine site in Northern
Territory of Australia is discussed.