The Bluff aluminium smelter has revealed it has another 75,000 tonnes of highly toxic hazardous waste stored in buildings at Tiwai Point - and does not yet know what to do with.
Government officials say it is not clear if the smelter company can be held liable to clean up Tiwai Point.
Newly released documents show the waste has already caused "severe" cyanide pollution.
Phil Pennington is looking into this.
