The salvage operation to remove diesel fuel and pollutants from the sunken HMNZS Manawanui off the coast of Samoa has been successfully completed, marking a significant step in minimising environmental risk in the area. The New Zealand Defence Force (NZDF), working alongside specialist salvors, has achieved its objective of extracting as much fuel as possible from the wreck, ensuring the surrounding marine environment remains protected as much as possible.
A challenging but crucial operation
The fuel recovery effort was no small feat. Over the course of the operation, divers conducted an astounding 284 dives into some of the most difficult-to-reach parts of the ship, accessing a total of 55 tanks and compartments. Ten additional tanks were known to be empty or free of pollutants and were left undisturbed. Commodore Andrew Brown, Senior National Representative for the NZDF, praised the effort, stating:
“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.”
Despite the complexity of the task, salvors worked methodically to extract fuel, seal tanks, and prevent further leakage. Their efforts resulted in the successful removal of over 320,000 litres of diesel fuel mixed with seawater. From this, more than 300,000 litres of usable diesel fuel was recovered, while an additional 45,000 litres of liquid, including waste oil and diesel-contaminated seawater, was removed for safe disposal in New Zealand.
Environmental monitoring confirms safety
The fuel extraction process also provided valuable insight into the extent of damage sustained by the vessel’s tanks during the grounding. Some diesel had already escaped through damaged tanks and pipes, while a portion was consumed in the fire that broke out before Manawanui sank. Despite this, NZDF divers worked tirelessly to contain ongoing leaks and ensure minimal impact on the surrounding waters.
Ongoing environmental monitoring has yielded reassuring results. According to Commodore Brown:
“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.”
Regular testing by the Scientific Research Organisation of Samoa has reported consistently low hydrocarbon levels in the water, indicating that the seawater and marine life remain uncontaminated. Consequently, the precautionary zone restricting fishing in the area was lifted—welcome news for the local community.
What comes next?
With the primary fuel removal phase complete, attention now shifts to the next critical phase of the operation. Salvors will begin the removal of equipment, weapons, ammunition, and debris in and around the vessel to ensure the site is left as safe and secure as possible. Any recovered materials, along with the remaining unprocessed liquid waste, will be transported back to New Zealand for safe disposal.
Commodore Brown reinforced the NZDF’s commitment to the operation:
“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.”
This operation marks a significant milestone in the ongoing management of the Manawanui wreck, reflecting the dedication and expertise of all those involved in mitigating environmental risks in the region.
