Dendrobium mine ‘cracks’ surface in Area 3B, report finds

WATER WORRIES: The front gates of the Dendrobium mine at Mt Kembla. Picture: Adam McLean
WATER WORRIES: The front gates of the Dendrobium mine at Mt Kembla. Picture: Adam McLean

The ground is bulging and cracks are reaching from the surface to the coal seam in a section of our drinking water catchment above the Dendrobium mine, according to an independent study commissioned by the State Government.

The extensive study, by consultants PSM and commissioned by the Planning Department, found the effects of bulging – including under and around Cordeaux dam – “do not appear to be recognised or incorporated into modelling” by the miner, South32.

Bulging is a type of ground movement produced by underground mining.

“Investigations at [one] site showed new cracks extended through to the ground surface and the permeability increases post-mining by one to three orders of magnitude” – or as much as 1000 times, the report found.

The study was prompted by Fairfax Media reports in 2015 which revealed the miner had won approval for more longwall mining without submitting a water impact assessment that matched the planned mining.

The miner ordered one water study but kept its findings secret, then was granted more longwalls whose height was dubbed the “most aggressive” by any mine in the region’s water catchment.

Environmental groups have long highlighted the subsidence resulting from the extraction of coal was clearly leading to the drainage of surface rivers and aquifers. Those concerns were partly borne out in the 2016 Audit of the Sydney Drinking Water Catchment that was quietly tabled last month by the Berejiklian government.

The PSM results go further than the audit. The report found sensitive upland swamps – endangered ecological sites which play an important role in moderating surface water flows – were being affected by the Dendrobium mine “at distances of around 250 to 900m” from the mining panels.

The report stressed its findings related to just the single monitoring site above the 3B area of the mine, and that “”a number of gaps and uncertainties” remain. Still, the fracturing over longwall number 9 was “100 per cent of the cover”.