An underground metals mine in New South Wales has made efforts to plug a hole made during exploration drilling that accidentally breached the tailings of an abandoned mine.
Workers were drilling towards the abandoned mine when water and tailings began rushing in from the drill hole.
About 6–9m of water flowed into the work area in total, prompting the team to work overnight to plug the sudden inrush, which was flowing at a rate of 15–20 litres per second at 40 pounds per square inch.
The area was excluded from access while an engineering solution was developed.
An investigation by the NSW Resources Regulator discovered drilling into the old workings struck unconsolidated tailings.
“There are many regions in NSW where abandoned mines interact with active mines,” the Regulator said.
“It is the duty of the mine operator to ensure that robust mine planning considers the likelihood of water bearing abandoned workings and develops systems to avoid those workings.”
There is an estimated 80,000 inactive mines in Australia waiting to be rehabilitated. Western Australia launched an abandoned mines program in 2015 following the enactment of the Mining Rehabilitation Fund Act.
Geological Survey of Western Australia (GSWA) developed an inventory of abandoned mine site features within Western Australia between 1999 and 2011, finding total of 189,530 mine site features throughout the state.
The program forms the state’s first dedicated and perpetual fund for the rehabilitation and management of historical abandoned mines.
NSW’s own legacy mines program is an initiative from the state Government that delivers and manages works to reduce significant risks from out-of-use mine sites.
Current mine operators are responsible for mine rehabilitation under the Mining Act 1992.
All current operating mines must lodge a security deposit for the full cost of rehabilitation at the commencement of operations. That security deposit is used to cover remediation costs if the mining lease holder fails to fulfil their rehabilitation obligations.
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