An international law expert has warned that abandoning oil and gas infrastructure in Bass Strait would breach Australia’s obligations under international law, if ExxonMobil pursues this plan in decommissioning its Gippsland offshore project.
Donald Rothwell, who specializes in international law at the Australian National University, said Bass Strait was used for international navigation and had special status under the UN convention on the law of the sea (UNCLOS) and related International Maritime Organisation (IMO) guidelines.
As a party to the UNCLOS, Australia was obliged to remove all structures from Bass Strait when they were no longer in use, he said.
UNCLOS and related IMO guidelines were “unambiguously clear,” Rothwell said: Structures in an international strait within Australia’s exclusive economic zone couldn’t be left “in situ.” “There’s actually an obligation to remove those structures,” he said.
When decommissioning its 50-year-old fossil fuel infrastructure in the Gippsland basin, located up to 77 km off Victoria’s Gippsland coast, ExxonMobil proposed to leave steel structures below depths of 55 m “in place on the seabed.”
In a September update, the company said lower sections of steel structures in deep water would remain, with removal “part of a future decommissioning campaign, unless an alternative end state is proposed and accepted by the regulator.”
The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) said full removal was “the base case for decommissioning” unless it was satisfied that environmental risks and impacts could be reduced “to as low as reasonably practicable and an acceptable level” in an accepted environment plan.
ExxonMobil has said it will submit its plan in early 2025.
The Wilderness Society sought Rothwell’s legal opinion after ExxonMobil stated its intention to resubmit plans to leave steel structures in the ocean to NOPSEMA and the federal environment department.
The Wilderness Society campaigner Fern Cadman said Rothwell’s advice demonstrated a clear requirement under international law for the government and its offshore regulator to insist on full removal.
“NOPSEMA needs to crack the whip on ExxonMobil to avoid a scenario where the company no longer has financial capacity for clean up and taxpayers are left meeting Australia’s legal requirement and footing the bill,” Cadman said.