Fuel and toxins may still be on board the sunken HMNZS Manawanui as the New Zealand Defence Force (NZDF) claims the salvage company has completed their work.

According to NZDF, over 320,000 litres of diesel fuel mixed with seawater has been removed with only just over 300,000 litres of usable diesel fuel extracted. Another 45,000 litres of liquid including waste oils and diesel fuel/seawater has also been removed and will be returned to New Zealand and processed for safe disposal. Final amounts would be confirmed once assessments are complete.

When the sink sank, it was reported that the Manawanui was carrying more 900,000 litres of diesel and the leakage was estimated to be around 200,000 litres.

NZDF’s Commodore Andrew Brown said the objective at the start of this work was to remove as much of the fuel and other pollutants on board as possible and this had been achieved.

He said the salvors using their considerable knowledge and expertise reached and checked all tanks and in some cases compartments, and other locations that could contain diesel fuel, oil and other pollutants.

In total 55 tanks or compartments were reached and checked.  Ten tanks were not accessed as they were known to be either empty or not to contain pollutants.

A total of 284 dives were made, with typically two divers for each dive.

“This was some of the most challenging diving operations – accessing the ship’s hardest-to-reach tanks – those at the very bottom of where Manawanui lays on its side. As liquids have been extracted, tanks have been sealed,” Commodore Brown said.

“The recovery work has given us a clearer picture of the damage sustained to tanks during the grounding.   We know diesel fuel escaped through damaged tanks and pipes. Some were consumed in the substantial fire on board before the ship sank. Our Navy divers also worked hard to contain and capture ongoing leaks.

“Continuous environmental monitoring has shown earlier diesel fuel that did escape to sea, dissipated relatively rapidly, evaporating from wind and wave action, as this type of light diesel fuel is known to do. This was also confirmed by an independent international assessment.”

NZDF said there may be small amounts of residual diesel fuel remaining somewhere in the vessel but were confident the salvors had been extremely careful and thorough, checking tanks and in some cases compartments and other locations that could contain diesel fuel, oil and other pollutants.

“Regular testing by the Scientific Research Organisation of Samoa has reported consistently low hydrocarbons and confirmed the seawater and marine life in this area are clear and uncontaminated. As a result, the precautionary zone in the area that carried a warning on fishing was reduced and then removed – a very welcome outcome for local communities,” said Commodore Brown.

“Significant efforts have got us to this stage and the work doesn’t stop here. The salvors have turned now to the removal of equipment, weapons, ammunition and debris from in and around the ship and then making it secure.”

“Our priority continues to be to minimise any possible environmental impacts, and to do a careful and thorough job. As I have always said, this Operation will take time, but we are committed to doing the right thing.”