Emergency services were called to the Riverside Drive site shortly before 3pm and found the man in cardiac arrest, a NSW Ambulance spokeswoman said.

He could not be revived.

Police believe the workman was standing near a tip truck being loaded by an excavator when its scoop bucket came loose and crushed him.

The man, who has not been formally identified, sustained significant head and chest injuries, they said.

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Police and WorkCover representatives visited the scene and investigations are continuing.

A spokesman for WorkCover NSW said they were investigating the incident.

''Initial enquiries indicate that the male worker was struck by an excavator bucket and died on the scene as a result of his injuries,'' the spokesman said.

''WorkCover inspectors are attending the site and will conduct a full investigation before preparing a report for the Coroner.''

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