By Dr. Gavin Mudd (MPI/Monash University)
In early February, the Mineral Policy Institute (MPi) and the Tasmanian Public & Environmental Health Network (TPEHN) co-hosted a tour of abandoned and legacy mines in western and north-eastern Tasmania. The tour was led by Isla Macgregor from TPEHN and Dr Gavin Mudd, the Chair of MPi, as well members of the public and two PhD students from Monash University.
Tasmania has a rich history of mining, including famous projects such as the Mt Lyell field at Queenstown – more infamous for its extreme pollution of the Queen and King Rivers and the tailings delta on the mouth of King River as it enters Macquarie Harbour – as well as Rosebery, the Zeehan and Dundas fields, Mt Bischoff, and lots of others. While sites like Mt Lyell are vast in their scale of impacts and well known, the numerous smaller sites are often never recognised for their ongoing impacts – with the most common impact being caused by acid mine drainage or AMD. The generation of AMD is caused by sulfide minerals in rock being bought to the surface environment and allowed to react with large amounts of water and oxygen – causing the sulfide to chemically change to sulfuric acid, which in turn dissolves lots of salts and heavy metals to form a toxic leachate which is lethal to aquatic ecosystems.
The joint MPi-TPEHN tour visited about two dozen mines across western and north-eastern Tasmania – with most being long abandoned and a few still operating. The extent of AMD problems was pervasive, with every site on the west coast showing some signs of AMD getting into the local environment – from very small scales but regularly repeated in the Dundas fields, to flowing down urban drains and streams in the town of Zeehan to whole rivers being biologically dead at Queenstown. Given the trend of growing mine wastes being produced every year by the mining industry, the various sites highlighted the importance of detailed long-term risk assessments of mine waste and its management.
The north-east of Tasmania was once a great alluvial tin mining field, where large dredges and sluicing operations would carve up valleys to extract tin. In this areas the scars in the landscape are extensive, sometimes with lakes left behind instead (although the extent of water quality impacts remain unclear and poorly assessed).
Overall, the trip has provided valuable insights into mining legacies in Tasmania – and real field evidence of ongoing problems from long abadonded mines as well as operating mines. In the near future, the photographs from the numerous sites will be added in detail to the Mining Legacies website, providing for a more informed understanding of the extent of mining legacies and the debate about mining – and, as always, it remains MPi’s position that the long-term environmental legacies mining can leave are still being under-estimated by government and industry.