The incident took place around 2 p.m., Tuesday, June 29, at the site located at 1175 Route 112 in Port Jefferson Station, said the Suffolk County Police.
Sixth Squad detectives said the hole was approximately four feet by four feet and the man dropped 14 feet.
The victim, an adult man, was transported to Stony Brook University Hospital for treatment of serious injuries.
The Occupational Safety and Health Administration (OSHA) was notified.
Click here to follow Daily Voice Massapequa and receive free news updates.