Slide Background
Slide Background

UNDERSTANDING THE HYDROGEOLOGY OF BAUXITE RESIDUE DISPOSAL AREAS AT THE WORSLEY ALUMINA REFINERY, COLLIE, WESTERN AUSTRALIA

Wright, R.F. Davidge, S.C. Speechly, A.M. Johnston, P.B.

Detailed hydrogeological characterisation of a bauxite residue disposal area (BRDA) at Worsley Alumina’s Collie Refinery has been used to support closure design investigations. The investigations have included the drilling and installation of piezometers, water balance calculations, field and laboratory estimation of hydraulic parameters, and groundwater modelling.

Hydraulic parameter estimations are most important for the reasonable prediction of future underdrainage flow rates from the BRDA and the success of re-vegetation. These data have been estimated from a variety of field and laboratory methods and confirmed by water balance calculations and groundwater model calibration.

The water balance work indicated that the capillary fringe does not follow the BRDA phreatic surface fluctuations. The fringe stretches between winter (when it is close to the phreatic surface) and summer (when it is at its most distant).

The development of a satisfactory conceptual groundwater model was critical to the successful development of a predictive (mathematical) groundwater model.

Predictive groundwater modelling has been performed to estimate the likely future underdrainage flow from the BRDA. These predictions were necessary for planning of post-closure liquor collection and treatment (or other disposal method).