The Northern Territory Environment Protection Authority (NT EPA) has completed a rigorous environmental impact assessment of McArthur River Mining Pty Ltd’s Overburden Management Project and has concluded that the Project can be managed to avoid unacceptable environmental impacts and risks.
NT EPA Chairman, Dr Paul Vogel, said the NT EPA identified potentially significant environmental impacts and risks associated with the Proposal and made 30 recommendations to avoid and mitigate those potential impacts and risks.
The Proposal was referred to the NT EPA in June 2014 following the erroneous classification of waste rock.
The classification system used by the Proponent while operating the open cut mine to 2014 did not match the actual characteristics of the rock being mined and led to a significant under-estimation of the volume of reactive (potential to generate acidic/metalliferous/saline drainage) waste rock.
The previously approved waste rock dumps were not designed for the storage of the high proportion of reactive waste rock that was actually mined, and this became evident in 2014 when the Northern Overburden Emplacement Facility waste rock dump began emitting plumes of sulfur dioxide, giving the appearance of being on fire.
The Proposal comprises essential alterations to the design of the primary waste rock dump and updated options for closure of the mine site from the previous Phase 3 Development Project that was approved in 2013.
The NT EPA examined the existing effects of the McArthur River Mine on the environment, and concluded that the McArthur River is currently in good condition and impacts are generally restricted to the mine site at present. However, the Proposal has the potential to result in future off-site impacts and risks.
The NT EPA determined that maintaining the health of the McArthur River must be the central focus for all future stages of the mine.
The NT EPA’s key recommendation establishes an overarching environmental outcome that ensures the health of the McArthur River is protected along its whole length at all times from mine-related impacts. All management and regulatory action should be focused on achieving this outcome.
“The NT EPA has concluded that the McArthur River, in terms of water quality and aquatic ecosystems, is in good condition at present based on a review of available monitoring data”, Dr Vogel said.
“However, the McArthur River and the values it supports is the critical aspect of the receiving environment for the Proposal that links all identified key environmental factors and that must be protected from mine-related degradation.
“The NT EPA therefore considers that to meet its environmental objectives, and the principles of ecologically sustainable development, the McArthur River must be maintained in a healthy condition at all times.
“This overarching environmental outcome is the basis for the recommendation that the proposal should be allowed to proceed.”
The NT EPA recommended improved source control of contaminants and stronger governance and regulatory oversight at the mine to enhance transparency and community engagement. Furthermore, all environmental monitoring programs should be reviewed and the results of all monitoring be made publicly available.
The NT EPA also recommended replacing the existing review boards with panels of independent experts to review and advise on technical matters relating to the waste rock dumps, tailings storage facility and mine closure. Each expert panel would report publicly.
To improve community engagement and involvement, the NT EPA recommended new arrangements for a Community Reference Group, chaired by an independent person appointed by government.
“If the Proposal is implemented in accordance with the overarching environmental outcome and the NT EPA’s 30 recommendations, there are good prospects of ameliorating environmental problems at the mine,” Dr Vogel said.
The NT EPA has provided its assessment report to the Minister for Environment and Natural Resources, Eva Lawler, for consideration.