Comparison of field and laboratory data in relation to cover design on TSF closure

Abstract

Developing designs for closure covers of tailings storage facilities is challenging and typically requires modelling using various climatic and material-specific assumptions. In many cases, data for the site are limited and the designer must make assumptions in order to carry out the design analyses. This can lead to overly conservative modelling, which in turn results in conservative, more expensive solutions. Closure models rely on climate data and unsaturated material parameters as the key inputs and there can be considerable errors if the climate data or unsaturated parameters are inaccurate. In order to provide site-specific climate information, as well as unsaturated parameters, field moisture content and matric suction measurements of the desiccation and resaturation cycles of sulphide nickel tailings located in an arid climate have been collected over a period of two years, along with climate data from a weather station installed at the site. These data are compared with a numerical model calibrated against data collected during a laboratory column test carried out under controlled conditions, which showed close agreement with the field data. This paper presents a comparison of the field data collected to a model that was calibrated against laboratory column data. The calibrated model data showed good agreement with the field data and suggest that the results of predictive modelling are likely to be reasonable for closure cover design purposes.