Mountain Journal has previously highlighted the potential environmental impacts of the Stockman project, which would see a major mine re-opened in the headwaters of the Tambo River.

In the following story, Scott Campbell-Smith outlines the economic cost of the previous mining operation and the risks associated with a major expansion of the mining operation.

The new minister for Energy and Resources will need to make a final decision on this project shortly.

Author: Scott Campbell-Smith

Mt Polley Mine tailings dam failure
Mt Polley Mine tailings dam failure

About two weeks ago, Saturday31/1, the Canadian Environmental Protection Agency released its report into the causes of the failure of a tailings dam at Mt Polley, British Columbia. The report concludes that failure was caused by subsidence in the foundations beneath the dam wall that were weaker than assumed during the design phase.   The mine operators had increased the size of the dam annually until this weakness became disastrously apparent on August 4th 2014.

Mt Polley was an open pit, copper and gold mine operated by Imperial Metals. The tailings dam contained 25 million tonnes of waste water contaminated with cobalt, nickel, antimony, arsenic, lead, selenium, mercury and cadmium. It’s failure is the biggest environmental disaster in the history of the province of British Columbia, destroying the drinking water of several towns and a fishery. It is uncertain when or if these will every recover owing to the tendency of heavy metals to accumulate in some parts of an ecosystem.

In identifying the underlying geology as the cause of the disaster the report says the mine engineers cannot be held accountable because they were not required to examine that geology in such detail. They are more critical of the way the mine and dam were planned, operated and maintained, which left no margin for safety, and the inability of regulators to ensure compliance with standards.   They also recommend that design standards for tailings dams and operation standards urgently need updating to be best practice. Commentary around the disaster has drawn attention to the political donations made by the majority shareholder of Imperial Metals to B.C.’s Liberal Party and the influence of the mining lobby over Canadian politics.

All of which might sound far away and irrelevant but in East Gippsland we have a very similar situation at Benambra.

The mine operated by Dehnurst Mining between 1992 and 1996 left behind a dangerous mess, demonstrated gross regulatory failures and unsafe operating practices, and enjoyed broad political support (as an interesting side note, MP and former Premier Ted Baillieu was a shareholder). The tailings dam still leaks and operates on a flow through system so it remains a source of heavy metals contamination into the Tambo River and hence the Gippsland Lakes.   Tailings of this type remain dangerous for approximately 1,000 years but may be stored in a chemically stable state under water. Cleaning up the mine and tailings dam after Denhurst declared bankruptcy cost Victorians $6.9 million. The State also invested $5.8 million in the mine, built a road for the mine costing $2.9 million, awarded the mine a royalty holiday valued at $ 1.2 million, and undertook ‘project facilitation’ valued at $.5 million (total cost to Victorian taxpayers $17.3 million, not including environmental costs).   It would not be difficult to think of better ways to spend $17.3 million taxpayer dollars in East Gippsland.

A proposal by Independence Group to re-open the mine and expand the tailings dam to ten times its current size (from 700,000 tonnes to 7 million tonnes) was approved in 2014 by the former State Planning Minister and Federal environment minister, and will soon go to the State’s new Mining minister for its final approval. The life of the mine is estimated to be 9 years. There remain significant questions, however, about the size and purpose of the bond required of Independence Group, the engineering adequacy of the proposed tailings dam and waste storage and the scale of tax-payer ‘investment’ in the mine.

During the proposal’s environmental effects study inquiry the Department of State Development, Business and Innovation calculated that a bond of $264 million would be required to monitor the site for a thousand years.   That figure does not include funds for maintenance of the dam wall, rehabilitation post-mine or in the event of disaster.   The former Planning Minister commented publically that the bond for the mine should be $5 million and the public funds should make up part of that figure. The mine proposal includes the possibility that some tailings will be stored in disused mine-shafts but whether the mine can afford this expensive and difficult process and how this will be done safely has not been established.   The existing tailings dam wall relies on part on a plastic lining with a maximum life of 30 years and a concrete lining with a life of 80 to 100 years. There is no known safe way to get underneath the existing 700,000 tonnes of toxic material to repair these dam membranes.   The proposed enlarged dam would rely in part on a plastic lining with a maximum life of 100 to 200 years.

The stage is set at Benambra to repeat dangerous, ecologically destructive – if not disastrous – and expensive mistakes of the past. The cost of the previous operation to the taxpayer was more than $17 million. How much will the new operation cost us? The engineering has at best a slim chance of being safe, the bond very likely to be utterly inadequate, and the enormous cost of Independence Group’s brief period of profit-making is likely to fall, sooner or later, on the pubic purse.

When the dam wall fails, as the engineering reports specify it sooner or later will, we can hope it’s a small, repairable leak rather than bursting. If it bursts or leaks very badly Swifts Creek will lose its water supply. Because heavy metals tend to accumulate, if it bursts then water from the Tambo will be unusable for agriculture, fish from the Tambo and the Gippsland Lakes will be unsafe for consumption for decades, at least. That is the current situation at Mt Polley.

The few jobs that will be produced, over a relatively brief period, and the profits Independence Group may make (if they don’t go bankrupt as Denhurst did) do not measure up to the risks.