SOUTH32, MOUNT KEMBLA
Waterways affected: Cordeaux reservoir and catchment, Avon reservoir and catchment, Pheasants Nest weir catchment.
The Dendrobium Mine is an underground coal mine located in the Illawarra Escarpment, near Mt Kembla. Dendrobium is owned by South32, who also owns the Appin/West Cliff Colliery and explorations nearby.
Longwall mining at Dendrobium began in April 2005, and has continued 24/7 since. This mining occurs beneath the Upper Nepean sub-catchment of the Special Areas of the Greater Sydney Water Catchment.
South32 is currently untaking longwall mining in Area 3B, with extraction largely complete in Areas 1, 2 and 3A (1). Dendrobium has development approval to mine Area 3B and 3C until 2030, however it expects to have depleted these areas by 2024.
- Dendrobium Mine Expansion Proposal
Proposed areas to be mined in Dendrobium’s “Plan for the Future” are Areas 5 and 6.
Areas 5 & 6 expected to yield 9.6% thermal coal, 75.5% coking coal & 14.9% pulverised coal for injection (PCI). Coking coal & PCI are used in steel production.
The proposed longwalls will be 305m wide, and up to 4km long. Subsidence is expected to be 2 – 2.4 metres at the surface, with resultant cracking in overlying rock layers.
The longwalls in Areas 5 and 6 would end only 300m from Avon Reservoir, and 630m from Cordeaux Reservoir. In contrast, other major infrastructure is generally required to be set back 1000m from reservoirs, due to the risk of damage to the reservoir.
(Detailed!) Reasons to oppose the Dendrobium Mine Extension
The Dendrobium Mine Extension Project proposes 28 years of destructive longwall mining in the water catchment for Wollongong, Macarthur and Sydney. It will result in damage and loss of water to swamps, water courses and the Avon, Cordeaux and Nepean Reservoirs. Sydney is the only city in the world that allows longwall mining in a publicly owned water catchment. The proposed mining is in the protected “Special Areas” of the water catchment upon which 5 million people rely for drinking water. Dendrobium already has the highest water loss of any mine operating in the Greater Sydney Water Catchment area. This proposed expansion would more than double the water loss from our catchment due to mining operations.
The Department of Planning, Industry and Environment (DPIE) has acknowledged the damage that the expansion will cause, and yet still supports the expansion. DPIE in its assessment report says:
“Anticipated subsidence impacts include fracturing of streambeds and diversion of surface water underground; losses from the reservoirs due to increased permeability in the solid rock mass separating them from longwall voids; and impacts on surface water quality, including an increase mobilisation of metals such as iron. Stream function would be impacted due to cracking of creek beds, loss of pool holding capacity and loss of baseflow reporting to streams from upland swamps and near-surface aquifers.”
The proposal seeks approval to continue longwall mining into two new areas – Area 5 and Area 6 – to mine 77.2 million tonnes (Mt) of Run of Mine (ROM) coal over 28 years, with up to 5.2 Mt ROM coal per year extracted. This would be about 80% metallurgical coal and 20% thermal coal.
- Mining induced subsidence will damage the watercourses and swamps that feed our drinking water reservoirs
South32 predicts that it’s 305 metre wide long wall panels may result in subsidence of 2m to 2.45m. Previous mines of similar width have caused 2.5m to 3 m of subsidence, so South 32’s prediction may be conservative.
The mining and associated subsidence will also cause cracking of the land on the surface – including rivers, creeks, smaller watercourses and swamps that feed our drinking water reservoirs – and subsequent water loss to the catchment. No level of damage is acceptable to the Special Areas.
The mining will come to within 300m of the Avon and Cordeaux Reservoirs. It will result in water losses from Avon, which is the only source of water supply to over 310,000 residents and businesses in the Illawarra region, as well as Cordeaux Reservoir, which along with Cataract Reservoir is the main water supply for Camden, Campbelltown and Wollondilly council areas and even as far afield as Nepean Reservoir, which is the water supply for the nearby towns of Bargo, Thirlmere, Picton and The Oaks.
All three affected reservoirs, Avon, Cordeaux and Nepean also supply water to Sydney.
As an important component of the Greater Sydney Water Catchment, these reservoirs supply between 20 and 30% of Greater Sydney’s water in normal times, and in times when Warragamba is compromised by water quality (for example the 1998 cryptosporidium and giardia water crisis, or the 2019/20 black summer bushfires which burned the Warragamba catchment) they may supply even more.
In dry years, the watercourses in the mined area that flow into Avon Reservoir are expected to totally dry up.
- Millions of litres of water will be lost
The cracking and dewatering of watercourses, swamps and aquifers is expected to add the loss of many more millions of litres of water each day to the 10 million litres daily water loss from Dendrobium’s current and past mining.
Dendrobium’s average daily water loss for the duration of the expansion project will be 22 million litres (ML). Water loss will peak around 2032 to 2036 at 26ML per day. This is equivalent to the daily water usage of 130,000 people!.
The existing water discharge into Allans Creek, Unanderra will double.
This is the same discharge point that was recently identified as exceeding safe levels of heavy metals.
South32 wants to purchase water licenses and pay cash compensation to WaterNSW for the water they take from the catchment. This cannot possibly compensate for irreversible damage to the Special Areas and for the legacy of water loss. The water loss has been modelled for the 171 years from 2048 to 2319.
- Government agencies outside Planning are concerned
The NSW Government’s Independent Advisory Panel for Underground Mining has said,
“It is not possible, at this stage, to be comfortable that the worst-case losses from the surface water regime have been identified. Stream depletion can arise from combinations of reductions in overland and groundwater flow to the streams and increases in stream losses to the groundwater.”
Water NSW has also questioned the reliability of the modelling stating that “previous iterations of the model had predicted surface water take at the existing Dendrobium Mine and that these predictions had increased 5-fold in the 5 years since 2014 (now 1372 ML/year)”.
WaterNSW has been clear that mining in the Special Areas causes loss of yield to the reservoirs and the swamps and water courses that charge them.
- Damage to WaterNSW infrastructure
The mining expansion risks damage to critical WaterNSW infrastructure, including the dam walls of Avon and Cordeaux Reservoirs, the Lower Cordeaux Dam Project and WaterNSW’s Deep Water Access Project. It is even expected to cause ground movement at the dam walls.
WaterNSW’s Deep Water Access Project aims to provide water security for the Illawarra by constructing a deep water pumping system to access the reservoir’s deeper waters.
Avon Dam is the only source of water supply to over 310,000 residents and businesses in the Illawarra region and yet, WaterNSW says that the Dendrobium Extension Project could affect its ability to construct and operate this important infrastructure project.
The mining is also too close to the dam walls. WaterNSW stated that the 1000m setback from the dam walls is not enough and the setback should be at least 1500m, adding that, “Should any impacts occur to these dams, there is the potential that the risks and consequences could be extreme.”
- Water quality
As water courses fracture due to mining induced subsidence, metals will be dissolved and leach into the water. This will lead to an increase in metals in the water courses and reservoirs. Furthermore, this increase will worsen in the 100 – 200 year period of groundwater recovery.
WaterNSW in particular expressed concern about the levels of metal contamination, stating,
“WaterNSW is concerned that any increase in arsenic (or other heavy metals) may have a negative effect on water quality and aquatic ecology.”
- Damage to Upland Swamps
The upland swamps of the Woronora Plateau play an important role in the water catchment by capturing and holding water, filtering it and in times of drought releasing it slowly into the creeks and rivers that feed into the reservoirs.
These swamps are also classified as Endangered Ecological Communities (EEC) and are significant in terms of their biodiversity.
The upland swamps provide a mosaic of permanently wet peaty soil within a dry sandstone landscape. Each swamp is a unique island community containing rare plants and animals. The specialised flora and fauna of the EEC also carry individual protection at species level. Dewatering the swamps will result in local extinctions in breach of multiple layers of State and Federal legislative protection.
There are 46 swamps in the mining area and 25 of these are expected to be cracked by the mining. Water drains away from swamps into the mining void, the swamps dessicate, the flora and fauna die off, and dryland species take over. The swamps lose their capacity to hold water in drier times. They are more prone to erosion and more prone to bushfire. Research shows that swamps that have been undermined are less able to recover after bushfire compared to swamps that were not undermined.
Coastal upland swamps also provide carbon capture and storage ecoservices.  Neither South32 or DPIE have considered or estimated greenhouse gas emissions associated with expected swamp destruction, or loss of carbon uptake that the swamps currently perform.
- Bushfire risk
Dewatering of the forest, bushland and swamps above the mining will make the area more prone to bushfire. The water catchment was one of the few unburnt areas of bushland in the 2020 fires and it needs to be protected from mining induced degradation. It is also close to the highly populated residential areas of Wollongong that are located along the Illawarra Escarpment; making the catchment more fire prone makes the escarpment more fire prone.
- A legacy of water loss and contamination for future generations
It will take 100 years for groundwater levels to stabilise in Area 5 and 200 years for Area 6. Thus the drawdown/dewatering impacts of the mining will remain long after we are gone. This is a problem that we will hand down to future generations, descendants that will be more challenged by climate change, subject to more extreme weather events, longer and more severe droughts and more serious bushfire risk.
The NSW Independent Advisory Panel for Underground Mining says that,
“At this stage, because there is a lack of clarity as to if and how Dendrobium Mine can be sealed, it should be assumed that surface losses from the catchment will occur over the long term and potentially in perpetuity.” 
The discharge water from the mining will also need to be managed and treated, perhaps in perpetuity, and this is another burden that we leave for future generations. Previous mining at Dendrobium has already burdened future generations with a legacy of water loss and contamination and this expansion will make it much worse.
- Damage to valuable Aboriginal Cultural Heritage
A legacy of mining induced damage to Aboriginal Heritage sites at Dendrobium was recently revealed in the media.
The Aboriginal Cultural Heritage Assessment records and physical survey of only 6.91 % of the affected area, identified 58 Aboriginal heritage sites, including six new sites, in the area likely to be affected by longwall mining in Area 5 and Area 6. These were mostly rock shelters with/without art and deposits, and axe grinding groove sites located in creeks.
Although the DPIE’s Biodiversity Conservation Division proposed changes to South32’s mine design to avoid impacts to six Aboriginal heritage sites, changes were made by South 32 that would protect only one site. In a statement that was justifiably and understandably described as offensive by the Illawarra Local Aboriginal Land Council, the Department said:
“The five remaining sites are all located centrally above longwall panels. Given the limited risks of impacts, the Department does not consider that the scientific or cultural benefit of avoiding the risk of impacts is warranted.”
Monitoring of Indigenous cultural sites is required but there is no requirement to preserve or avoid these sites, and no penalties to South32 when it destroys them. It is reprehensible for mining interests to desecrate Aboriginal Cultural Heritage whilst the area remains out-of-bounds for the Aboriginal community.
- Locking in 28 years of Greenhouse Gas Emissions, instead of decarbonising
The IPCC 2018 Special Report warned that to limit global warming to 1.5°C then, globally, by 2030, primary energy from coal needs to have reduced by a minimum of 59 %. In this context, this coal mining extension proposal spanning 28 years (to 2048) should not even be considered.
The proposal is estimated to create up to 23.7 million tonnes of CO2e in the production stage (“Scope 1 and 2 emissions”) and 237 million tonnes in the transport and consumption of the metallurgical coal produced (“Scope 3 emissions”). This brings the total emissions to between 256 million and 260.7 million tonnes of CO2e for the life of the project.
The DPIE will not consider the Scope 3 emissions from the consumption of the coal, arguing that these are the responsibility of the consumer. To put the volume of emissions in context, the federal government estimates Australia’s greenhouse gas emissions for the year to December 2018 as 538.2 million tonnes.
Thus, approval of this mine would lock in emissions over the 28-year life of the project equivalent to 48% of the 2018 annual emissions for all of Australia. Annually it would add an average of 9.3 million tonnes per annum (260.7 million tonnes over 28 years) of CO2e to the atmosphere.
This is comparable to 1.73% of Australia’s current annual emissions.
Australia is a major greenhouse gas polluter: in 2016 Australia had higher emissions than 90 % of all countries; had the seventh highest emissions per capita; and even worse as an exporter of GHG emissions, ranked third after Russia & Saudi Arabia for exports of fossil fuel CO2e potential. Coal makes up more than 80 % of this export.
The emissions from combustion of coal that Australia sells (i.e. scope-3 emissions) are very significant. Australia needs to take responsibility for them as well and rapidly transition to zero carbon steelmaking.
- NSW Government locking in 28 years of destructive coal mining is irresponsible economic planning
We need to rapidly reduce greenhouse gas emissions to address global warming. One of the obvious – and appropriately ambitious, given the climate emergency – ways to decarbonise industry is to start with steel.
Port Kembla has been identified as having good prospects for moving from existing fossil fuel-based steel-making to making low-emissions steel. This transition would not only retain jobs in the Illawarra, it would position Australia well in the emerging low-carbon future.
- No alternative is provided to this shockingly destructive expansion which will cause permanent damage to our water catchment
There should be no mining in the Special Areas of Greater Sydney Water Catchment; this is the stated position of WaterNSW and the legislated purpose of Special Area protection.
It is outrageous that DPIE not only support this destructive mining expansion, but the Department also required no alternative mine design options to reduce the damage should an expansion proceed. Having failed to explore any alternatives, the DPIE is claiming without evidence that narrower longwalls would still cause significant damage and “would come at an unsustainable economic cost” for the mining company.
The NSW government requires South32 to consider alternatives, including mining in domains for which they have existing approvals and modifying the design to “avoid key sensitive surface features, including swamps and water storage infrastructure”. South32 have failed to address these imperatives and yet the Department has supported the proposal rather than uphold standards of responsible planning.
 Dendrobium Mine – Plan for the Future: Coal for Steelmaking, Groundwater Assessment for South32 – Illawarra Coal, NPM Technical Pty Ltd trading as HydroSimulations, 2019, p 101 accessed at:
 Department of Planning, Industry and Environment, Assessment Report, Dendrobium Mine Extension Project, State Significant Development SSD-8194, October 2020, (“DPIE Assessment Report” p. x, Accessed at: https://www.ipcn.nsw.gov.au/projects/2020/10/dendrobium-extension-project-ssd-8194
 Subsidence Report for Dendrobium Mine, MSEC, 2019, pp 35 – 37, accessed at:
 WaterNSW Fact Sheet – Illawarra Water Security Project, November 2019, accessed 9.11.20 at: https://www.waternsw.com.au/__data/assets/pdf_file/0007/150757/Avon-Deep-Water-Access-Fact-Sheet-Nov-2019.pdf
 DPIE Assessment Report, op cit, P. xii
 On average, each person in Sydney uses about 200 litres of drinking quality water every day. From: https://www.sydneywater.com.au/sw/education/drinking-water/water-use-conservation/index.htm
 DPIE Assessment Report, op cit, p88
 DPIE Assessment Report, op cit, p. 68
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 Environmental Assessment Part 2, Section 6, pp 150 – 151 accessed at:
 Environmental Assessment Part 2, Section 6, pp 150 – 151, op cit
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