Characterisation of Uranium Mining and Tailings Pond Areas by Integrated Remote Sensing, Geophysical, Geological and Hydrogeological Methods

Abstract

Remote sensing, geophysical, geological and hydrogeological methods were used to characterise the aquifer of a proposed uranium mining and tailings pond area in India. Examination of lithologs show uranium occurrence at the Eparchaean unconformity at a depth of about 50 to 60 m below the surface. Resistivity studies showed four distinct zones-top soil, highly weathered, moderately weathered/fractured rock and massive rock. Wells tap groundwater from the weathered and fractured zones. Highly weathered nature of the intrusives, dykes and faults do not allow them to act as barriers to groundwater flow. Rainfall is the major source of groundwater recharge apart from irrigation return flow. Recharge to unconfined aquifers is primarily by downward seepage of rainfall through the unsaturated zone. Groundwater flows towards southeast. Pumping tests resulted in hydraulic conductivity of this aquifer ranging from 5.4 to 19.3 m/d. Infiltration rates were obtained at 1.5 and 2.3 m/d for clayey residual unconsolidated materials and 3.7 and 5.2 m/d for sandy residual unconsolidated materials. Secondary data were used to verify the results of field tests and investigations. Results from this study were also successfully used in radionuclide and geochemical modelling of the effects of leaching from the tailings pond on groundwater quality and its impact on human health. This detailed study provides a wider understanding of the sub-surface characteristics of the proposed uranium mining and tailings pond area which offers useful information for future research and development activities.