— — The Occupational Safety and Health Administration has cited the DuPont Yerkes factory in the Town of Tonawanda for 17 serious violations following an explosion at the plant last November that killed one contractor and injured another.

DuPont was fined $61,500, the maximum under OSHA law, after a chemical storage tank that a contractor was welding ignited because highly flammable vinyl fluoride fumes had seeped in from a connected tank, the investigation found. The resulting explosion at the River Road facility, which Tonawanda Police said killed the worker instantly, was felt as far away as Grand Island.

The contracting company, Buffalo-based Mollenberg-Betz, also was cited for eight serious violations and fined $55,440.

Mike Stratton, the assistant Buffalo area OSHA director, said the November accident “certainly could have been prevented.”

“There was a number of things that happened that we believe were violations of standards and a couple of things that should have happened didn’t happen,” Stratton said.

The OSHA investigation found that the tank, which had previously contained a polyvinyl fluoride slurry used in making solar panels and some interior airplane parts, was supposed to be empty and thoroughly cleaned prior to the welding work. It had been emptied, but it was still connected to two other full tanks and fumes seeped through connecting pipes. OSHA said the pipes should have been disconnected, but they weren’t and that the tank should have been vented to allow any trace fumes to escape, but it wasn’t.

Additionally, Stratton said DuPont workers conducted the necessary air monitoring in the area outside the tank, but not inside the tank, where the fumes existed.

He also said that the two contractors had no idea that they were doing welding work on a tank that had previously contained such a flammable chemical — something they should have been told.

The contractors themselves were not without fault, either, the investigation found.

“(Mollenberg’s) responsibility is to provide a workplace that is free from recognizable hazards, whether it’s on their own site or someone else’s site. They should have recognized the issues in question, as well as the host employer, DuPont.

“You would expect that the things that should have been done ... would have been done,” Stratton said. “This was not anything uncommon to industry.”

Both companies have 15 days to request a conference to discuss the investigation and could challenge the findings in court.

A DuPont representative could not be reached to comment Thursday.