Because miners cannot leave final voids in America the industry has developed methods that make backfilling economic.
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The US they passed a federal law in 1977 called the Surface Mining Control Reclamation Act (SMCRA), which in simple terms says surface mines (their version of open cut mines) must return the land to its pre-mining landform.
US miners must have plans that include returning the land to its Approximate Original Contour (AOC) according to Rod Eckels from Landforma who spoke to The Argus about his experience of working in that country at the Mine Rehab Conference.
Mr Eckels said before mining starts a surface map of the site is prepared and from that a plan is developed to return the land post-mining to that AOC.
“The AOC is at the heart of the mine plan from start to finish,” he said.
The AOC is at the heart of the mine plan from start to finish.
- Rod Eckels
“They do it successfully in the US and we should should look at doing the same in Australia.”
Mr Eckels said our way of mine planning and design is way too cost prohibitive to develop an AOC policy – we have to transport the backfill too far with our mine methods.
But in the US they design their mines differently and reshape as they go by cutting half the mine to start with and having the backfill adjacent to that void, he said.
“It works in the US simply through the mine design and how they operate the mine because it removes the double handling of the backfill,” Mr Eckels said.
Also attending the conference was University of Newcastle project officer Nigel Stace who wants to see all the vital information about the region’s voids such as size and depth and location made readily available to the public. He also wants mining practices modified to ensure no voids remain post-mining.
“The industry says its too expensive here to backfill but we know from overseas experience in particular in the US they have mines plans that result in no voids,” he said.
“Voids mean we as a community are subsidising the mining industry – our governments are giving miners a de facto subsidy.”