The nickel company Vale in New Caledonia says its plant will remain closed until at least late December.
Vale suspended operations a week ago after it became known that an effluent pipe leading through a lagoon of a World Heritage site was broken.
It says an investigation has shown that there was too much air in the pipe, causing it to burst.
The CEO, Stuart James Mcnaughton, has told Les Nouvelles Caledoniennes that there were not enough valves installed for the air to escape.
He also says the leak detection system in the pipe was not working either.
He says the fracture was discovered less than two weeks after it occured, and there has been no impact on the environment.
Mr Mcnaughton says repairs should start early next month and the plant could re-open in late December.
