Police said the unnamed German contractor was in his 30s and died in an incident yesterday morning at the Cemex factory in South Ferriby.
The worker was carrying out repairs after the plant flooded in the tidal surge on the Humber Estuary in December.
Humberside Police said it was investigating with the Health and Safety Executive and Cemex to establish what had happened.
A spokesman for Cemex said: “All operations and work at the plant have been suspended.
“We are working with the relevant authorities to investigate and fully understand the circumstances of this tragic incident. Our thoughts are with the contractor’s family and friends.”