Tailings Dam and Sink Holes
Is the tailings dam safe?
The dam is continuously monitored by a specialist mine tailings consultancy working to established ANCOLD (Australian National Committee on Large Dams) guidelines, and is regularly inspected by ERR.
Favourable local environment conditions for the long term stability of the dam include low rainfall and low seismic activity.
Could the tailings dam overflow?
It is unlikely the dam would overflow as the walls have been raised incrementally since initial construction to safely increase and manage storage capacity.
Stawell Gold Mine (SGM) are required to maintain the dam level 0.6m below full capacity.The tailings level of the dam is reported to Earth Resources Regulation (ERR) every two months and provided at ERC meetings. The most recent readings identified that the tailings level was 1.8m below full capacity; well within the 0.6m requirements.
Is there a risk of collapse due to underground mines?
In 2015 ERR initiated a technical review of Stawell Gold Mine operations including community consultation.
The Review of Environmental Performance by Dr Peter Beck stated:
'While there does not appear to be a study that assessed the risk of sinkholes developing in response to blasting by SGM, no records of such events were provided for the review.
Therefore, while the potential for sinkholes developing as a result of collapse of underground workings cannot be discounted, the risk appears relatively low and can be addressed by an appropriate assessment in areas affected by blasting where historical mine workings are underlying residential areas.'
In response to Dr Beck's report, ERR issued a Remedial Notice (BA01160002) requiring SGM to engage a geotechnical engineer to assess the potential risk for a sinkhole developing.