Tri-State Generation & Transmission has completed its investigation into an incident that sent several workers to the hospital about a week ago, but the company is no closer to finding out what happened.
Tri-State reported last week that between midnight and 1 a.m. April 18 and 19, employees of various subcontractors at the Craig power plant were taken to The Memorial Hospital after suffering from nausea, coughing and burning eyes.
Everyone taken to the hospital was working inside the plant's third power unit on a $39 million environmental renovation.
Tri-State plans to install new burners to limit oxides of nitrogen emissions, upgrade the plant's smokestack scrubbers and complete a variety of maintenance tasks.
The company was unable to find what caused the incident and plans to proceed with the renovation project, Tri-State Communications Manager Jim Van Someren said.
"We worked on that for a week and did not find anything, so we're moving on," he said.
Although Tri-State finished its investigation, the Occupational Safety and Health Administration has not.
OSHA, which first sent an investigator to the plant April 20, does not plan to end its inquiry until a cause is found, OSHA area director Herb Gibson said.
"No, we're going to do a thorough investigation to determine the cause of people getting sick, along with any other occupational illnesses that may have occurred," he said. "We're very far from closing our investigation."
Tri-State researched several theories, Van Someren said, such as a possible leak in an acetylene tank used by welders in the area where people became sick but could not prove anything conclusive.
The project itself is back on track and fully staffed, he added.
Van Someren did not know if the workers who had to be taken to the hospital still were working at the site.
The overall renovation project was delayed slightly by the incident and subsequent investigation, he said, but company officials expect to be able to catch up and finish the total project within the original six-week timeline. In that case, the power plant would be back to full output by the end of May.
Collin Smith can be reached at 875-1794 or email@example.com.