Rena salvage could end in March

The spot where Rena sits under water. Salvors say the timeline for clean-up is unclear. Photo / John Borren

Salvors of the wreck of the Rena are unable to say how long the clean-up will last because of the vagaries of the weather.

A remote-controlled grab, a giant magnet and divers were continuing the three-phase operation to clean the debris field to a depth of 35 metres.

The massive task was detailed to the city council yesterday by Keith Frentz of Beca consultants.

He said the difference was absolutely stunning once the last stage of the clean-up, divers manually recovering the remaining seabed items like scattered aluminium ingots, had completed their work.

Quizzed how long the clean-up would last, he said the weather was the big unknown. "That will determine how long they will be there." The operation had been forecasted to run until March next year.

Mr Frentz said 243 containers were left in the vicinity of the ship, with a further 32 drifted away and sitting on the seabed. All but two were in depths greater than 50m.

He said there were no toxic materials in the 243 containers, although he drew a distinction between toxic materials and contaminants. Salvors were investigating where a container of contaminants, fine copper wire, was located on the wreck.

Asked about the stability of the separated bow and stern sections of the Rena, he said gravity would eventually take the stern section over the edge of an underwater cliff and down to depths of about 70m.

Two main pieces of the bow section weighing about 1100 tonnes were stuck on top of the reef. Three other sections weighing 130 tonnes were wedged in a crevice about 18m down. Mr Frentz said 490 tonnes of hull debris had been removed this year including 57 tonnes from the bow section.