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A tailings dam near the head of the Tambo River in Victoria’s east would be dramatically expanded under plans for a new copper and zinc mine, prompting fears from environmentalists about potential long-term impacts on waterways.
The proposed mine is expected to produce 850,000 tonnes of tailings – waste from mining – a year, with at least half to be put into an expanded dam and covered with water. The dam will need to exist into perpetuity to stop oxidisation of the tailings, which can cause water and soil pollution.
The expansion of the old tailings dam – which would be at least 37 metres high – comes after the state government spent millions of dollars to rehabilitate the site last decade after an earlier mine went out of business in the 1990s.
Under the project – about 60 kilometres north-east from Omeo – a million tonnes of ore will be extracted annually for nine years. The mine's proponent – the Independence Group – said 250 jobs would be created at its peak. It said more than $1 billion would be invested and almost $900 million in economic value generated for the Gippsland region.
Planning Panels Victoria is reviewing the Independence Group’s environment effects statement for the mine, with its report expected this month.
Environmentalists have told panel hearings the size and lifespan of the tailings dam means the project is too risky at the headwaters of a major river. The Tambo River runs from the Victorian Alps into the Gippsland Lakes.
Louise Crisp from the Gippsland Environment Group pointed to ongoing seepage of acidic water from the existing dam and the likelihood the expanded dam’s membrane would break down in coming decades as reasons for concern.
"There is no way the community can be confident that the dam wall will not fail sometime in the future or the water levels will be maintained for the next 1000 years," she said.
A report by consultant GHD for the Department of State Development, Business and Innovation said the detailed design work for the tailings dam had not yet been carried out and there were many areas of missing data in the plans, but the preliminary objectives were in accordance with best-available practices.
Independence Group project manager Rod Jacobs said it had done further work since the GHD report. He said detailed design work would occur at a later approval point for the mine as was standard practice.
He said the company did not believe there would be substantial leaking from the tailings dam and it would consider GHD’s suggestion of a solar power pump as a contingency if man-made material at the site weakened or broke down in the future.
"While the mine life will be nine years, the government will supervise a fund that will ensure safe environmental management of the tailings dam for as long as required."
Environment editor, The Age