A nickel expert says questions need to be asked about Vale's risk management procedures, workers' behaviour and the design of its processing plant in New Caledonia to find out why spills keep happening there.
Operations have been suspended at the Goro plant for more than two weeks after 100,000 litres of effluent, containing some acid, ended up in a creek.
Environmentalists and the indigenous population are calling for the plant, which is next to a World Heritage Site and has had five spills in five years, to be shut permanently.
Gavin Mudd, from the School of Environmental Engineering at Monash University, says the scale of the plant has always raised concern.
Dr Mudd says it's up to Vale to find out what's going wrong.
"It is a legitimate question to say well why do they seem to be having some big accidents that are very, very significant, whether it is a spill of sulphuric acid or other things. It's an open question and it's certainly up to Goro at the moment to work out what's going wrong and fix it, and fix it well."
An environmental engineer, Dr Gavin Mudd.
Vale has declined numerous requests for comment.