BHP Billiton’s GEMCO operation has reportedly suffered four uncontrolled manganese spills following Cyclone Lam, the Northern Territory EPA says.
The miner reported four manganese ore discharges at the site due to heavy rains caused by Cyclone Lam, the ABC reports.
The cyclone hit the Northern Territory Coast as a category four, late last month, passing over GEMCO, the Ranger uranium mine, and Rio Tinto’s Gove alumina site.
According to the EPA the rains hit the stockpile, washing out a retaining wall, which allowed the manganese to discharge into the sea.
"The discharge occurred during a period [of] very high rainfall during a cyclone," NT EPA head Bill Freeland said.
"The circumstances of that we are still investigating."
He went on to say that discharge poses no environmental concern.
"This thing gave way during heavy rainfall repeatedly, the things that came out were manganese concentrate, which is manganese dioxide. It's pretty insoluble and sank to the bottom," he said.
A BHP spokesperson confirmed the incident.
“BHP Billiton GEMCO operations reported 4 occasions of stormwater discharging from their port lease during heavy rainfall during February to the Northern Territory department of Mines and Energy and the Northern Territory Environmental Protection Agency.
"These incident reports were made in compliance with the relevant Northern Territory legislation, and continues our commitment to be transparent in our environmental performance.
The miner also agreed with Freeland's statements on its potential environmental impact.
The miner accidentally dumped two tonnes of manganese iron ore into the sea at its port facility in 2010.
At the time, NT Resources Minister Kon Vatskalis stated: “To their credit GEMCO immediately reacted and they put a container under the conveyor belt and also dredged the area where the manganese was dumped into the sea.”
However he did voice disappointment the incident was not reported for nearly a week.
Regarding the most recent spill, Freeland said investigations are ongoing.
"You've got be careful about what you do. You can't just say 'you've been negligent or terrible or anything like that'," he said.
"You've got to really investigate and find out what happened."
Freeland went on to applaud GEMCO’s quick reporting of the incident.
Under their existing licensing arrangements, they have to notify us of any untoward thing, any incident, anything contrary to the license … and that's what happened," Dr Freeland said.
"They're dutiful people and they provided the information we looked for."
GEMCO is not set to remain a BHP company for much longer, having been flagged to be spun out in the upcoming demerger, and placed in the new entity South32.
BHP has been contacted for further comment.