A worker was hurt when a digger plunged 20m (60ft) into a rubbish pit at a recycling plant.
The accident happened at the Waste to Energy plant in Bar Road, Coventry, the city council said.
It took three hours to rescue the man, who was treated for "relatively minor injuries".
The authority said it was "co-operating fully" with emergency services and the Health and Safety Executive.
West Midlands Ambulance Service said crews were called at 10:30 BST.
The council said the incident happened away from the tip area of the site, which remains open to the public.
Ambulance service spokeswoman Claire Brown said paramedics worked with the fire service's rescue team to help free the man.
He was taken to University Hospital Coventry and Warwickshire, she added.