UPDATE 5th February 2021:

Independent Planning Commission REJECTS Dendrobium Mine expansion. 

Read the IPC's Statement of Reasons for Decision

Dendrobium mine is an underground coal mine located near the beautiful Mt Kembla in the Illawarra Escarpment. Dendrobium is operated by South32, a subsidiary of BHP Billiton. South32 also owns the Appin/West Cliff coillery and explorations nearby.

Longwall mining began in April 2005 and has continued to operate 24 hours a day, 7 days a week. This longwall mining is beneath the Upper Nepean sub-catchment, part of the Special Areas of the Greater Sydney Water Catchment. 

Longwall mining is the most destructive form of mining possible. Long gone are the days when hundreds of miners were employed to chip away at a coal seam with hand picks. Now huge machines called shearers rip through a "wall" of coal typically 250 - 400 metres wide. As the shearer removes coal, hydraulic supports hold the roof of the coal seam up. As the shearer moves forward, the roof collapses behind it. This causes subsidence (vertical sinking) and fissures to appear in the ground above. 

Longwall mining
Longwall mining

Cross-sectional view of Longwall mining operation (source: Dendrobium's submission to Planning NSW)


The longwall shearer or power loader, moves forward as it cuts coal - collapsing the roof behind it.

Subsidence model
Subsidence model

Model of subsidence associated with Longwall mining

Longwall mining
Longwall mining

Cross-sectional view of Longwall mining operation (source: Dendrobium's submission to Planning NSW)



South32 is currently untaking longwall mining in Area 3B, with extraction largely complete in Areas 1, 2 and 3A (1). Proposed areas to be mined in Dendrobium's "Plan for the Future" are areas 5 and 6. 

Dendrobium already has development consents until 2030, however current mineable reserves will be depleted by 2024.  Longwalls already approved and remaining:   Area 3A  (one); Area 3B (three) & Area 3C (seven). 

Areas 5 & 6 expected to yield 9.6 % thermal coal,  75.5 % coking coal & 14.9 % PCI.  Coking coal & PCI able to be used in steel production.

Screen Shot 2020-09-06 at 9.05.25 pm.png
Screen Shot 2020-09-06 at 9.08.50 pm.png

All images on this page are from South32's Dendrobium Mine – Plan for the Future: Coal for Steelmaking – Environmental Impact Statement (Executive Summary) (1).

Note the proximity of proposed longwalls in Areas 5 and 6 to Avon and Cordeaux dams - only 300m from Avon Reservoir and 630m from Cordeaux Reservoir. Major built infrastructure is required to be 1000m set back from reservoirs.

The proposed longwalls will be 305m wide, and up to 4km long.  Subsidence is expected to be 2 - 2.4m at the surface, with resultant cracking and huge water losses. South32 has only modelled these water losses out to the year 2050, despite their own modelling showing water losses will peak in 2046. 

Screen Shot 2020-09-06 at 9.22.01 pm.png

This image makes clear the sheer area of the Greater Sydney Water Catchment that has already been undermined, as well as the proposed Areas 5 and 6 that South32 want to mine - right in the middle of Cordeaux and Avon reservoirs.

Screen Shot 2020-09-06 at 9.22.24 pm.png

Consensus from independent experts is that the Dendrobium Mine's measures to protect these special areas of the water catchment are grossly inadequate. The following key findings are from the recent report by the Independent Expert Panel into Mining in the Catchment

  • Surface water that should be reaching dams is flowing into longwall mines

  • Current estimates are that existing mines are leading to the loss of 8 million litres of water each day, equivalent to 2,920 million litres per year, to Sydney’s water supply systems

  • Longwall mining can lead to drainage of swamps which is likely to be irreversible

  • There has still been no assessment of the long-term cumulative impacts of mining on water quantity and quality in the Greater Sydney Water Catchment.

Furthermore, WaterNSW is strongly opposed to the Dendrobium Mine Expansion, stating that "the project would cause an unprecedented level of surface­-to-­seam fracturing and groundwater depressurisation, which would result in a range of significant predicted impacts."(2)

(1) "Dendrobium Mine - Plan for the Future: Coal for Steelmaking - Environmental Impact Statement"

(2) WaterNSW Submission to Department of Planning, Industry and Environment, regarding Dendrobium Mine Extension Project.