More than 350 tonnes of oil spilled into the sea, killing hundreds of birds, covering Bay of Plenty beaches in black muck and leaving Maritime New Zealand with a clean-up bill that has so far topped $14 million.
The Rena's captain and second officer are facing charges over the incident while the ship's owner, Costamare Shipping, has refused to say whether it will cover the bill for New Zealand's worst environmental disaster.
Yesterday divers attached two hot taps to the starboard tank and had started pumping water into it.
Hot-tapping involves penetrating an oil tank underwater in a way that does not release oil into the environment.
Water is pumped into the tank, forcing oil to float to the surface, which allows salvors to extract it from the ship to the bunker barge Awanuia.
But a spokeswoman for Maritime New Zealand said the process would be slow. "It's a slow method, you are looking at four tonnes an hour and that's running at full steam as well."
MNZ salvage unit manager Bruce Anderson said dive teams had confirmed that the "coffer dam" or watertight barrier under construction to enable access to the starboard tank was unusable after heavy weather this week.
"Given the amount of time it would take to rebuild this, they have decided to focus their efforts on hot-tapping."
Meanwhile, another salvage team was continuing to pump the lube and hydraulic oils in the engine room into a centralised tank and into the Awanuia.
Salvage company Svitzer is also preparing to remove containers from the vessel.
The crane barge ST60, which is equipped with two cranes, will undertake sea trials before it is used to remove containers once the fuel recovery is complete.
Mr Anderson said Svitzer had engaged another large ocean-going barge from Singapore expected to arrive in early December. The barge can remove containers from within the ship.
On shore, clean-up operations around the Bay of Plenty continue with volunteer efforts yesterday concentrating on Papamoa Beach.
Nearly 8000 people have registered with MNZ's volunteer clean-up programme with 25 of those spending the past five days on Motiti Island where large quantities of timber and other pieces of container debris have washed up.
National on-scene commander Alex van Wijngaarden said volunteers had now dedicated 13,000 hours to the clean-up.
Opinion: Victoria Travers of WWF New Zealand on what we can learn from the Rena. http://bit.ly/kzWAO
