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December 2014

Phase Two of Debris Recovery Operations Well Underway

Ongoing debris recovery operations are well under way at the Astrolabe Reef (Otaiti).  As well as the large hydraulic ‘orange peel’ grab, a powerful electro-magnet is now being used to recover smaller metallic cargo and debris, including lighter hull plate sections.

Roger King of TMC Marine Consultants says that after an initial settling-in period, the magnet has achieved what salvors hoped in removing a lot of debris that the grab could not get.

“It doesn’t get the large volumes, as the hydraulic grab does, but it does get ferrous material from around the rocks that the grab can’t reach,” says King.

“The salvors like working with it as the crane driver can pick debris with little effort and the riggers on deck like it as it only gets the ferrous scrap and debris, which means less time sorting non-metallic materials, but importantly less potential for damage to the reef,” King says.

“The thousands of steel balls we’re recovering are a case in point – it would have been impossible without the magnet.”

Unsettled weather during November hampered recovery efforts and even when salvors do get out on the water, the rate of recovery has started to reduce considerably as many of the areas where they could access large deposits of debris have now been covered.

Since July this year the total amount of debris recovered is now 2,106 tonnes. Recovered debris has included significant quantities of container parts, scrap cargo, aluminium ingots, tyres, fibreboard and smaller quantities of wire.

Operations have also involved dive teams to aid in cutting more 547 tonnes of hull and bow structures for removal from shallow waters, which previously restricted the salvors’ access to debris.

The following video shows before and after footage to illustrate the extent of the ongoing debris recovery operation at Astrolabe (Otaiti) Reef. The footage was shot in the same location within the major debris field (between the bow and aft sections) in 12-18 metres of water. Note that the ‘after’ footage was shot before a third and final phase of the clean-up operation is carried out, involving divers collecting smaller items by hand.

The following images are from phases one and phase two of the operation showing the hydraulic crane grab and magnet in action, as well as the types of debris recovered. A third and final stage will involve diver teams to recover smaller items. An estimation of the debris remaining in the field is presently underway.