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Mineral Resources Tasmania

Drainage and Subsidence Repairs at Rossarden

Drainage and subsidence repairs, funded through the Rehabilitation Trust Fund, were completed at the former Aberfoyle Mine near Rossarden, Tasmania.

During mining operations at the Aberfoyle mine (1931-1982), coarse rejects were placed in a large dump near the crest of the slope down to Aberfoyle Creek. A recent erosion assessment determined that the coarse rejects dump continues to erode and requires a geotechnical management solution to limit potential impacts on Aberfoyle Creek.

To improve the stability and limit future erosion of the course rejects dump, a geotextile lined diversion drain was constructed to divert water around the course rejects dump along a defined and controlled flow path.

Additionally, ground subsidence was observed at two locations corresponding with the historic Northern Prospecting Shaft and Searles Shaft.

As part of the rehabilitation works, these areas of subsidence were repaired in order to reduce risks to public safety. The hole at the Northern Prospecting Shafts was backfilled with material from the coarse rejects dump and covered with a concrete cap. The sink at the Searles Shaft was tested for stability to determine if further subsidence would occur. Since no additional material was lost, the area was backfilled, compacted, and levelled out.

All works will be inspected regularly as part of ongoing rehabilitation management of the Rossarden site.

Drone imagery of diversion drain construction.