Concern over Gorgon leak

Safety and environmental concerns have been raised over the $50 billion Gorgon project on Barrow Island after a dredger ran aground on Sunday, spilling oil into water around the A-class nature reserve.

Maritime Union of Australia WA secretary Chris Cain said four crew were on the vessel, known as a "multicat", when it hit an anchor in shallow water, causing a 5m gash in the hull.

He alleged Dutch dredging contractor Royal Boskalis Westminster then tried to sail for Dampier but the crew refused, fearing it would sink.

"They ripped a five-metre gash in the ship's hull and ruptured a dirty oil tank which spewed oil into the water," Mr Cain said.

A spokesman for lead joint venture partner Chevron said there were no injuries and emergency response procedures were activated to secure the vessel and contain its fuel.

Department of Transport Marine Safety general manager David Harrod said a small amount of oil leaked but was contained.

A marine incident investigation was under way.

Greens MLC Robin Chapple said that under environmental restrictions the vessel should not have been near shallow water.

The project would be "an ongoing environmental disaster", she said.