MV Rena splits in two on a New Zealand reef, on Sunday, 8 January 2012. Maritime New Zealand

24 January 2012 (Radio New Zealand) – Salvage work on the Rena reached a milestone on Tuesday with all containers holding hazardous material now removed from the upper decks of the vessel. Thirty-two containers of dangerous goods, including flammable and toxic chemicals, were on board the Rena when it ran aground on Astrolabe Reef on 5 October last year. Maritime New Zealand says the containers on the deck of the ship were most at risk of being lost into the sea and it is a relief to have them safely removed. There are still a number of hazardous containers below deck, but the agency still does not know how many went overboard when the wreck broke in two on 7 January this year. Meanwhile, four fridges have washed ashore: one on Slipper Island, one on Matakana and two east of Opotiki. Some 2325 tonnes of waste has now been recovered from the sea and shores since the ship ran aground.

All hazardous containers removed from Rena’s deck

24 January 2012
By MICHAEL DALY Researchers are trying to work out how the mixing of different substances from the wreck of the Rena will affect the environment. The cargo ship ran aground on Astrolabe Reef off Tauranga in early October 2011, then split into two sections in heavy seas early this month, with the stern section slipping under the water a few days later. About 250 containers are estimated to have been lost overboard, while around 350 tonnes of oil was spilled in the days after the grounding, with a much smaller amount leaking out after the ship ripped apart. Among the 1368 containers in total on board the Rena, 21 contained the aluminium smelting byproduct aluminium trisodium hexafluoride, also known as cryolite. About 490 tonnes of the byproduct in total was aboard the ship. Although not declared as such in the original manifest provided to Maritime New Zealand, that material is classed as dangerous. Many of the containers of cryolite are now thought to be on the seafloor near the wreck. While cryolite is listed as “toxic to aquatic life with long lasting effects”, MNZ said the relatively small amount that may be dissolved would be massively and rapidly diluted. It was only slightly soluble in water, and the rate of release was expected to be diminished due to the packaging, with the material packed in 1-tonne bulk bags inside the containers. The bags had a polyethylene liner and were made of polypropylene, so were water resistant, but not watertight. Water was likely to have seeped into the bags within the container, MNZ said. Professor Chris Battershill, who holds Waikato University’s chair in coastal science, said that while the manufacturers considered cryolite to be relatively stable, the implications of it mixing with leaked oil products should be considered. Advice was being sought from chemists about what might happen if cryolite, or other dangerous goods on the Rena, came into contact with the hydraulic fluids, heavy fuel oil, and possibly diesel that had spilled from the ship. The petrochemical products might mobilise trace metal elements in the cryolite and possibly make them more available to the environment. Were that to happen aluminium signatures would be seen, and so far none had. A lack of research on such mixtures anywhere globally meant the issue was hypothetical. “Ships have been grounding around the world for a long time, but we seem to be somewhat in the dark ages in our ability to predict what might happen. We do not consider mixtures of contaminants in a real environmental context. To be prudent, we should,” Battershill said. […] A different kind of risk from the Rena was posed by the small plastic beads from the cargo that had fallen into the sea. The beads “go everywhere”, Battershill said. From studies in Australia they had been known to block the digestive tracts of seabirds and turtles, and persisted in the marine environment for a long time.

Environmental effects of Rena chemicals unknown