Future of Glencore’s McArthur River mine backed by NT EPA

Rehabilitation of McArthur River channel in progress in May 2012. Source: MRM

The Northern Territory Environment Protection Authority (NT EPA) has returned 30 recommendations after rigorously assessing Glencore’s overburden management project at the McArthur River mine in the Gulf of Carpentaria.

The project, operated by Glencore subsidiary McArthur River Mining (MRM), covers the company’s long-term management of McArthur River’s post-mine life up to 30 years from now.

MRM, in its environmental impact statement, said, “Like many mining operations, only a portion of the material mined at MRM is ore suitable for processing into metal.

“The leftover material is waste rock, or overburden, and includes topsoil, clay and other rock types. Different rock types can react differently when exposed to air and water.”

NT EPA chairman Paul Vogel said that there are potentially significant environmental impacts and risks associated with the proposal, citing that MRM’s classification of waste rock is “erroneous”.

“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 underestimation of the volume of reactive (potential to generate acidic or metalliferous or saline drainage) waste rock,” the authority said.

“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.”

But the NT EPA added that MRM can avoid casting unacceptable impacts and risks upon the environment, should the company comply with its recommendations.

The NT EPA said that the water quality and aquatic ecosystems of the McArthur River are currently in good condition. It also confirmed that at present MRM’s mine-related impacts are generally restricted to the mine site.

Among other proposals, the authority submitted recommendations to improve source control of contaminants; to enhance transparency and community engagement through stronger governance and regulatory oversight; and to appoint independent person(s) for the company’s existing review boards and community reference group, the latter of which is to be appointed by the government.

Vogel said, “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.”

The NT EPA’s proposal was made to protect the health of the McArthur River along its whole length at all times.