MINE subsidence of up to 3.1 metres is predicted if Chinese company Yancoal wins approval to expand its Abel underground coalmine at Black Hill.
Yancoal wants approval to lift production at Abel from 4.5million tonnes a year to 6.1 million tonnes and to extend its operations from 2028 to 2030.
Abel began in 2008 under different owners as a bord-and-pillar mine but Yancoal wants to introduce longwall mining to cut costs and increase the amount of coal recovered.
Yancoal plans to close its adjacent Donaldson open-cut mine later this year but is also seeking approval to lift production at the nearby Tasman underground from 1million tonnes to 1.5million tonnes a year.
The Abel lease runs under Black Hill and Stockrington across 2750hectares bordered by the Hunter Expressway, John Renshaw Drive and the F3 Freeway.
An environmental assessment on display with the NSW Department of Planning says the new Abel plans would meet the mine’s ‘‘existing subsidence commitments’’.
As well as the longwalls, Yancoal is also planning narrower, 120-metre ‘‘shortwall’’ panels.
Most of the subsidence is expected to be between 300millimetres and 1.7metres but the impacts could be substantially greater where the longwall goes under the long-closed Stockrington No.2 mine.
Yancoal’s experts say this ‘‘multi-seam’’ arrangement could result in 3.1metres of surface subsidence, or about three-quarters of the combined thicknesses of the two seams.
Although this would be in an area of the mine closest to the Hunter Expressway, Yancoal says subsidence impacts on the road would be ‘‘negligible’’.
It says existing subsidence impacts – including the ‘‘apparent sag of power lines’’ between power poles and surface cracks up to 375 millimetres wide – have been dealt with under a subsidence management plan.
Yancoal says the expansion would add another 10million tonnes of run-of-mine coal production, taking the remaining output to 65million tonnes.
Employment would increase at peak from 375 to 400, with about another 20 people employed at the Bloomfield coal preparation plant, which washes the coal on contract, taking its workforce to more than 50. The Abel plans are on display until March 19.