Setting the bar high with rehabilitation works at George Fisher Mine

There has been a significant transformation of two former waste rock storage facilities at George Fisher Mine, near Mount Isa, as part of essential rehabilitation works.

The final stages of works are underway on capping 230 hectares of mining land at the Handlebar Hill and Magazine waste rock storage facilities.

These were used during the mining of lead-silver-zinc at the Handlebar Hill open cut mine between 2007 and 2014. During that time, the two facilities received approximately 76 million tonnes of waste rock from the mine.

Glencore's Mount Isa Mines began work on rehabilitating the sites in 2017. Since then, almost six million tonnes of earth has been moved as part of reshaping and creating a 1.5 metre thick cover layer of non-acid forming (NAF) capping material over the sites.

Queensland Metals Superintendent - HSEC Environmental Long Term Planning, Sarah McConnell, says rehabilitation works are an essential part of life of mine planning and our social licence to operate in our communities.

"We're committed to minimising environmental impacts from our operations and are undertaking about $50 million worth of work in 2020 and 2021 to restore mined land across our Queensland operations."

We will be looking at the success of this project to set the benchmark for other rehabilitation works across our Queensland Metals business," says Sarah.

The project is being undertaken in collaboration with construction management team Infra-Struct and contractor QBC (Queensland Building & Civil).

Queensland Metals Technical Services Manager, Jody Todd, says almost 230 hectares of shaping and capping has been completed.

"This is a complex project and incorporates much more than just earthworks, with a detailed geochemical and geotechnical field investigation project undertaken to provide input into the design," says Jody.

"With this information, and using both internal and external consultants, a finalised landform shape was modelled to provide a protective NAF capping and a final surface to design the 26 drainage channels (4.1 kilometres) used to protect the final cap from water run-off during storm events."

"The seasonal runoff water will be directed into the site's sedimentation dams, which were expanded by an additional 550 megalitres as part of the project," Jody says.

"A very detailed quality assurance and quality control program ensures the project delivers on the design expectations by using the latest drone surveying technology and machine guided GPS."

"By using landform evolution modelling and dynamic storm water modelling we will ensure the capping works effectively into the future."

"The project is progressing well with drainage to be completed across the site over the next six months," Jody says.

In late 2018, the Queensland Government introduced legislation requiring mining companies to progressively rehabilitate land disturbed by mining activities as it becomes available and is no longer needed.