Preliminary hydraulic characterization of a fractured schist aquifer at the Koongarra uranium deposit, Northern Territory, Australia

• Main Author: Norris, James, 1953-
• Other Authors: Davis, Stanley N.
• Language: en_US
• Published: The University of Arizona. 1989
• Subjects: Uranium ores > Geology > Australia > Alligator Rivers Region.; Radioactive waste disposal > Research.; Hydrogeology > Australia > Alligator Rivers Region.; Anisotropy.; Schists > Australia > Alligator Rivers Region (N.T.).
• Online Access: http://hdl.handle.net/10150/291720

The Koongarra uranium deposit is hosted by quartz-chlorite schists. A conceptual model for the hydrogeology of the deposit is proposed on the basis of lithologic criteria and limited hydraulic testing. Water-level and aquifer-test data are presented that indicate the deposit lies within a partially confined, heterogeneous, anisotropic fractured-rock aquifer. The aquifer is dynamic with annual, diurnal, and semidiurnal water-level fluctuations. The results of aquifer tests indicate a high degree of connectivity in the aquifer. Fracture-dominated flow is observed in some tests, but the overall aquifer response appears to be that of an equivalent porous medium. A homogeneous, anisotropic model is used to estimate the transmissivity tensor for subregions of the aquifer. Anisotropy is well-developed with north- to east-northeast-oriented principal transmissivities. Northeast directions represent large-scale drawdown patterns and are subparallel to bedrock structure and the Koongarra fault. Northerly directions are localized and may reflect a less extensive fracture fabric or a flexure in the bedrock foliation.