"It was just a small impact point on the end of the bin.
"Initially emergency services thought he had been trapped between a digger and the bin, but that doesn't appear to be the case.
"He's got no external injuries at all."
Richard Schultze, team leader of Wellington Free Ambulance communications centre, said the man was treated by paramedics at the scene before being airlifted to Wellington Hospital.
Police and fire crews were also at the scene.
Howie said the hospitalisation was a "precautionary measure".
"He was walking around on site when the ambulance staff arrived.
"A preliminary investigation has not indicated any serious harm.
"He was out of sight from other operators so until we can talk to him and get that investigated we can't really comment on that [what caused the injury].
"We're hoping he's fine.
"We're obviously working through the investigation to ascertain what happened and make sure that we can ensure it doesn't happen again."
A police spokeswoman said police were called to the scene but the incident had now been passed on to WorkSafe to investigate.
- With Kapiti News