An offer for what the Government called the "Southland Transition Bond" was made in November. Kavinda Herath / Stuff What waste is being stored at Tiwai Point? But correspondence released under the OIA states the smelter's owners, Rio Tinto and Sumitomo, rejected the proposal. “Unfortunately, Rio Tinto and Sumitoto have declined to make any substantive remediation commitments prior to the finalisation of a preliminary disclosure plan next year, and has rejected the Government’s proposal of a bond payment linked to remediation, without tabling any alternative suggestions,” an email from Treasury commercial performance manager Maureena van der Lem to Rio Tinto’s general manager of energy, Andrew Horvat, stated in December.