New West Wall infrastructure at the Mount Isa Mines tailings dam

Mount Isa Mines is continuing to build major West Wall infrastructure at the Mount Isa Mines tailings dam.

The designs are aligned with industry guidelines and the timing of each stage is based on a deposition model of tailings from the concentrators, in order to maintain capacity.

Design and construction reports are submitted to the government as part of Glencore’s compliance requirement.

The West Wall comprises a 1.4-kilometre-long and 15-metre-high wall and spillway. The dam wall construction involved significant earthworks using around 500,000 cubic metres of material.

Construction activities in 2023 will raise the dam wall by 2.5 metres to maintain the freeboard and comply with the design storage elements of the system.          

The first phase commenced in 2019 when an embankment was built and later commissioned in January 2020.

The West Wall raise in 2023 incorporates an upgrade to the seepage collection system including trenches, pipes, drains and sumps.

The project is due for completion in late 2023.

For the initial project, large equipment was used, including 777 dump trucks, dozers and excavators.

Dry vacuum trucks were used to clean sediments and rocks from the cut-off trench. The use of these trucks eliminated the manual handling risks, saved time and reduced costs.

Naren Ramachandran, Superintendent - Engineering Regulated Dams says the project team has implemented leading industry practice by establishing a grout curtain.

“A successful wet season in late 2022 and early 2023 helped us to better design the seepage system for the West Wall. It helped us to understand the depth of the trenches to completely intercept any sub-surface seepage, making it a more effective system”, says Naren.

In conjunction with the project, the Environmental Water Studies and Projects team installed groundwater monitoring, observation and extraction bores within Black Star Open Cut, the Waste Rock Dump, Tailings Dam and West Wall footprints.