Chopper 11 was over the scene on Haywood Glen Drive and Old Knight Road as the man was loaded into an ambulance.
Shortly before noon, the worker fell about 20 feet into the trench that was partially shored up on one side.
He fell from the side that wasn't shored up.
The worker apparently has a broken leg but was able to crawl to a safe area where rescuers removed him using a basket.
The Raleigh Fire Department Technical Rescue Team assisted the Knightdale Fire Department with the rescue because of the "technical nature" of the operation, a town official said.
The worker was taken to a hospital for treatment.