When coal, rock or mineral ore is removed from an underground mine, the overlying earth can sink, which is called mine subsidence. The extent of mine subsidence depends on the mining method, local geology, depth of mining and amount of material extracted.
Mines are designed to manage and minimise the potential impacts of mine subsidence. For example, longwall coal mines can vary the width of coal extracted to reduce subsidence, avoid mining near sensitive features, or change the original layout of the mine. In other cases, the impacts of mine subsidence can be repaired or rehabilitated once mining is complete. The type of management measures used will depend on what features are present and what level of protection they require.
We’ve built upon years of experience to manage subsidence and there are many examples of mines successfully operating beneath infrastructure and alternate land uses – like under the Hume Highway and the Southern Rail Link
, mining under vineyards
and olive groves
Mine subsidence can sometimes affect built features, like homes or roads, or environmental features like rivers, cliffs and aquifers. Sometimes subsidence is unnoticeable, while in other cases it can cause visible cracks in building walls or the ground.
Mine subsidence is tightly regulated in NSW. When an underground mine is proposed the potential impacts of subsidence are assessed and are only approved if the government accepts that the proposed management measures will reduce potential impacts to acceptable levels.
The NSW Mine Subsidence Board
provides compensation or repair services where properties, such as houses, are damaged by coal mine subsidence.