After six months of being kept under wraps, reports on the impacts of a mine west of Wollongong have been released, revealing “disturbing” fracturing and bulging, putting Sydney’s drinking water catchment at risk.
The Dendrobium coal mine is located underneath the metropolitan special area, which provides a buffer zone of bushland around catchment areas to protect drinking water.
As well as seam-to-surface fracturing across parts of the mine, there has been an unexpected finding of valley bulging alongside Sydney’s major dams.
This can result in a loss of valuable drinking water from the catchment.
Mining and geotechnical engineer and UNNSW Emeritus Professor Jim Galvin conducted a review of the mine’s impact assessment report, and described the affects to the catchment as “grave, extensive and much more severe than warned of”.
“It’s now clear why [NSW Department of Planning] withheld these reports from WaterNSW, OEH [Office of Environment and Heritage] and the community for as long as they could,” he said.
Dr Galvin said the findings speak volumes about the department’s values, and financial returns from the mine seem to be more important than the integrity of Sydney’s primary health asset — drinking water.
“The mining underway in [one area] of Dendrobium mine is the most aggressive mining to have been approved in the special areas.
“And amongst the most aggressive anywhere in NSW.”
In approving mining at Dendrobium in 2013, the department embraced BHP Billiton’s rejection of a 2012 impact assessment that predicted seam-to-surface fracturing.
“[The department] did so without advising and consulting WaterNSW or advising OEH or the community,” Dr Galvin said.
The ABC has sought comment from the Department of Planning.
The Dendrobium underground coal mine (represented by the black dot) is seen in the metropolitan special area of Sydney’s drinking water catchment. (Supplied: Water NSW)
‘Whatever loss is occurring will only get worse’
National Parks Association of NSW mining projects officer Peter Turner agreed that the findings of damage were “greatly disturbing”.
“The reports are… revealing impacts some of which were anticipated, but some of which were not anticipated and all of which were more severe,” he said.
Experts say major catchment damage has been caused and the Government is allowing miners to withhold data. (ABC News: Billy Cooper)
Mr Turner said confirmation of seam-to-surface fracturing in what was supposed to be a protected part of the catchment was most worrying, as was the unexpected finding of bulging alongside Sydney’s major dams.
“The valley bulging, which then causes deformation to the rock underneath and around the reservoirs, generates leakage pathways from the reservoir into the groundwater system, so it is meant to be causing water loss around Cordeaux,” he said.
“It’s not known whether that is yet happening at Avon.
“For Cordeaux it is uncertain how much water loss is occurring but it is certain with more mining, whatever loss is occurring is only going to get worse.”
No figure has been put on how much water has been lost due to a lack of sufficient monitoring.
“Some of it will end up in the mine but some of it will get lost into deep groundwater flows that leave the catchment area all together,” Mr Turner said.
In 2015, the National Parks Association wrote a letter to the Department of Planning warning of fracturing.
In 2016, it advised in a report that the groundwater in reservoirs had been severely disrupted by mining.
Mine owners South32 provided a statement to the ABC and said the details within the report were being examined.
“We will continue to engage with government agencies and other key stakeholders to ensure continued compliance with consent conditions.”