An independent panel of experts in mining and water has released its Initial Report on the impacts of mining on water quantity in the Special Areas of Sydney's Water Catchment. The report was commissioned by the Department of Planning and Environment.
The Panel's Initial Report focuses on the Metropolitan and Dendrobium coal mines and includes recommendations to strengthen the monitoring and modelling of water impacts at both mines. Key findings include:
- Acknowledgement of the fundamental complexity of the technical issues and understanding required fully to understand water impacts.
- A recommendation to defer to the reliability of the Tammetta height of fracturing equation, which has been used at both Dendrobium and Metropolitan mines.
- Endorsement of the Department's current approach to the regulation of mining activities, including the requirement that mines seek iterative approvals before mining can take place and refer mining applications to independent experts and bodies for advice, and the imposition of strict conditions on approvals.
- Major efforts have been made at Dendrobium and Metropolitan mines in the last decade to undertake up-to-date and best practice groundwater models and modelling methods, using specialists and expert peer reviews.
- Advances have been made in knowledge around subsidence, groundwater, and surface water since these mines were first approved, and gaps in knowledge have also emerged that are relevant to mines in the catchment Special Areas.
- Previous investigations, modelling and monitoring at Dendrobium Mine have been insufficient for the scale and complexity of the technical issues relating to groundwater.
- It is difficult to verify that mining has had negligible consequence on surface water supplies.
- There is considerable scope for mine operators to improve Trigger Response Plans.
- Insufficient, variable and limited information restricting the scope and accuracy of calculations of groundwater and surface water diversion from the catchment into mine workings and other storages.
- The plausibility of an average water inflow of 3 megalitres a day of surface water and seepage from reservoirs being diverted into mine workings at Dendrobium mine, which may have otherwise reported into catchment dams. To put that into perspective, Sydney's catchment dams currently hold over 1.5 million megalitres, and it is estimated that up to 820 megalitres a day - around 300,000 megalitres each year – are typically lost in natural evaporation and environmental flows.
This is an Initial Report designed to prompt submissions to the Panel's ongoing work to develop further advice for the Department of Planning and Environment. The Panel will proactively engage with a range of stakeholders handing down its Final Report in August 2019.
The Panel will consult with interested stakeholders until late February 2019. These will include key government agencies such as WaterNSW, the Department of Industry, the Dams Safety Committee, the Office of Environment and Heritage and special interest groups such as the National Parks Association, Lock the Gate and community members.
A copy of the Initial Report is available on the Office of the NSW Chief Scientist & Engineer's website, along with details of how to make a submission to the Panel.
