Background
SGME was engaged to be responsible for the construction, monitoring and reporting of cover column trials (the trials) to meet the requirements of an environmental licence and inform closure planning strategies for a tailings storage facility (TSF). The mine is an underground operation located in north-west Queensland on Roseby Station pastoral leases. Its TSF is valley fill with two discharge locations to the north and south.
Objective
The mine is constructed, fully commissioned and has commenced depositing potentially acid forming tailings into the valley fill TSF. The mine’s environmental licence states cover trials must start shortly after tailings deposition begins. SGME were asked to undertake works which would meet the obligations described in the environmental licence and inform closure planning.
Solution
The project included two stages: a desktop assessment and the design and delivery of cover trials. The purpose of the desktop assessment was to determine a range of suitable cover options to progress to trials. An environmental risk assessment was prepared to define the design criteria for the covers.
Prior to delivering the trials, SGME developed a trial design specification that considered trial location needs, efficiencies, space for leachate capture and the use of artificial rainfall. Six columns were constructed and instrumented with volumetric water content and matric suction sensors to measure a maximum water balance. The maximum water balance was used to build a semi-calibrated one-dimensional numerical model. The model was then used to predict the performance of each cover under wet, average and dry scenarios.
The outcome of the project was a preferred cover composition and thickness to reduce tailings seepage potential. The early conceptual design of the cover paves the way for successful closure of the mine that is financially profitable, environmentally sound and socially responsible. SGME enhances cover and landform design through expertise in soil chemistry, physics, unsaturated soil mechanics and environmental engineering. Our innovative use of growth media amendments, revegetation strategies and engineering solutions improves cover and landform performance, reduces environmental risks and ensures long-term stability. We take a holistic approach that considers safety, stability, sustainability, cost-effectiveness and post-mining land use capacity to develop solutions that meet regulatory requirements and support sustainable practices. SGME’s commitment to continuous improvement through ongoing learning about technological advancements, regulatory changes and industry best practices ensures our designs remain innovative and sustainable, and ensures effective solutions for mine waste management are delivered that contribute to enduring environmental protection and responsible post-mining land uses.
