Remediation and rehabilitation project at Metalloys manganese alloy smelter

Working closely with the Department of Forestry, Fisheries and the Environment, the aim of the project was to reduce the risk of contamination of local waterways and remediate over 72,000 cubic metres of waste. The historic phosphate and phosphorous WSFs cover an area of approximately 3.5 hectares (nearly nine football fields) and were open with no liners, as they were not a requirement at the time of construction. Liners are used in storage facilities to prevent groundwater contamination.  

A capping and closure design was adopted for the WSFs, with construction works commencing in late 2023. The design included a slope at the top of the WSFs to enable effective stormwater runoff and they were lined with an impenetrable liner. Metalloys was able to reuse more than 30,000 cubic metres of coarse and fine slag for use in the shaping of the slope in their WSFs. Slag is waste created during the ferroalloy-smelting process.  

Progressive rehabilitation activities included re-spreading 300mm topsoil over the area and revegetating with local native species through hydroseeding, a process that enables emerging vegetation’s root systems to develop quickly. A monitoring system will assist Metalloys to measure rehabilitation effectiveness using specific success and completion criteria.  

The project took over 66,000 combined work hours from South32 employees and contractors. Of the 89 employees and contractors involved in the project, 40 were recruited from the local community. As well as supporting the local community through employment opportunities, Metalloys sourced goods and services from local providers where possible.  

The remediation and rehabilitation of the historical phosphate and phosphorous WSFs at Metalloys demonstrates our focus on the safe management of waste and contamination risks.  

Footnote: 

1. Metalloys was placed on care and maintenance in March 2020.