THOMASTON – Stepping on a piece of plywood may have caused a 23-year-old Cianbro worker to fall more than 50 feet last month amid silos at Dragon Products’ cement manufacturing plant.

It may have saved his life as well, a Cianbro official said Thursday.

Nick Wark of Plymouth, a millwright helper, didn’t break a single bone in the Feb. 26 fall, but he suffered internal injuries and collapsed lungs. He is expected to return to work Monday.

“Our assumption is he rode the plywood,” Alan Burton, Cianbro’s safety and human resources director, said in an interview Thursday. “The plywood took the brunt of the shock.”

Burton acknowledged that Wark was not wearing a safety harness.

Exactly what occurred – and what went wrong – is the subject of an investigation by the U.S. Mine Safety and Health Administration, an agency of the Department of Labor.

Carl Liddeke, district supervisor at the administration’s Manchester, N.H., office said Thursday that the federal report is being reviewed at the agency’s offices in Pittsburgh. He did not know precisely when it would be released. “I expect it to be forthcoming,” he said.

Pittsfield-based Cianbro is the contractor for a $40 million expansion at Dragon Products’ vast operation along U.S. Route 1 near the Thomaston-Rockland line.

Cianbro’s internal review concluded that the cause of the accident was twofold: failure of workers to secure a piece of plywood and Wark not wearing a body harness tied to a fall-arrest system.

The company investigation found that Wark was working in an area at the top of the silos where a piece of equipment was being installed.

Burton said the opening Wark fell through had been covered with a sheet of plywood secured by “cleats,” which were simply wooden two-by-fours.

Workers trying to arrange more room for work removed the cleats from the plywood and placed the plywood over the hole again. But they did not resecure the temporary flooring with wire or bolts, as they should have, Burton said.

“They didn’t look at the new hazards,” Burton said. “They didn’t think about it, unfortunately.”

When Wark stepped onto the plywood to continue working, it slipped out of place.

“So when the plywood went down, he went down,” Burton said.

Safety harnesses are required only “if there is a falling hazard,” Burton said. “It was a secured area,” including handrails. “It was all set up so they could work without a harness.”

After the fall, it took specially trained rescue crews two hours to lift Wark from the deep space through a rope system. He was flown by helicopter to Central Maine Medical Center in Lewiston, where he underwent surgery, Hutchins said.

Company officials are still shaking their heads at Wark’s speedy recovery. Measurements show Wark fell 58 feet, not 52 feet as originally reported.

“He’s a lucky young man,” Burton said.

Burton did not yet know whether MSHA would issue violations or impose fines, but indicated Cianbro would not take internal disciplinary action. “The people involved have probably suffered the most that you could suffer,” he said.

Wark’s co-workers are grateful that he is expected to have a full recovery, Cianbro spokeswoman Dottie Hutchins said Thursday.

Wark, who has worked for Cianbro for about two years, was at the Pittsfield office Thursday, talking with fellow employees and eager to return to work, Hutchins said. Wark declined to talk with a reporter.

He will begin working two days a week, Burton said, and hopes to be back full time in about six weeks.

According to Hutchins, Wark does not remember anything from the time he fell until a week later.