Suddenly in the glare of public scrutiny, an obscure New York supplier of industrial glues, Powers Fasteners Inc., yesterday vigorously denied federal investigators' assertions that the firm squandered the best opportunity to fix the epoxy error behind last year's fatal Big Dig ceiling collapse.
Powers officials knew or should have known that the bolts supporting the massive concrete ceiling panels might have been secured with the wrong glue, a Powers- brand epoxy that weakens over time, according to the National Transportation Safety Board, because it had supplied this type to the Big Dig. But Powers failed to alert Big Dig officials about this possibilty when bolts holding up the ceiling of the Interstate 90 connector tunnel began slipping during construction, a top federal investigator said in an interview yesterday.
As a result, the glue failed, the panels fell, and a Jamaica Plain woman, Milena Del Valle, perished. It remains unclear who used the wrong glue in the first place. But safety board officials said there was ample opportunity to detect that error.
"Why didn't Powers ask, 'What kind of glue is being used here?' " Bruce Magladry , the agency's lead investigator, said in an interview yesterday. "It was such a simple thing to ask. And Powers never asked it."
The NTSB summary report, released Tuesday in Washington, faulted Bechtel/Parsons Brinckerhoff, the consultant hired to manage the $15 billion project, and Modern Continental Co., the builder of the ceiling, for not monitoring the slipped bolts after first identifying the problem in 1999.
Compounding federal investigators' frustration, Powers officials declined to cooperate with investigators during the yearlong probe, and one employee refused to answer questions in a deposition, invoking his Fifth Amendment right against self-incrimination, according to documents released by the federal agency.
Powers -- a privately-held, 200-employee firm with estimated revenues of $40 million -- has emerged as a major target of the investigations stemming from the tunnel tragedy, joining the more familiar names of Bechtel/Parsons Brinckerhoff; Modern Continental; and Gannett Fleming, the connector ceiling designer.
"Powers was in the best position to ask the right questions when problems first became apparent in 1999," Magladry said.
In October 1999, some epoxy-secured ceiling bolts in the connector tunnel began to "creep," or slip out of the concrete roof. The construction and design firms convened seeking the cause. Powers joined in, aware at least at the corporate level that it had shipped Big Dig workers two types of epoxy: quick drying fast-set epoxy, which weakened with time, and standard-set, which did not.
Powers representatives said yesterday that the firm never considered the possibility that the wrong epoxy had been used, for two reasons. First, the Powers representatives sent to Boston from corporate headquarters in Brewster, N.Y., in 1999 agreed with assessments by Bechtel/Parsons Brinckerhoff and Modern Continental that the ceiling bolt slippage had been caused by installation problems.
And second, they say, Powers shipped the standard-set epoxy earmarked specifically for use in the ceiling, leaving its representatives with no reason to believe the kind of degradation that occurs in fast-set epoxy was the cause.
"The suggestion from the NTSB is that Powers just sent out fast-set epoxy willy-nilly, and that just isn't so," said Karen Schwartzman, a consultant hired as Powers's spokeswoman.
She said documents show that Powers sent about 1,000 tubes of fast-set epoxy to Modern Continental, then another 120 tubes of standard-set. The dates on the records suggest that the standard-set was intended for the ceiling, as opposed to the walls, where the fast-set epoxy could have been used safely. The standard-set was shipped Aug. 3, 1999, shortly after ceiling construction began.
"Powers was operating under the assumption standard-set was used," said Schwartzman. "There was no reason to question that. Everything pointed to installation problems."
But the NTSB disagrees. Magladry does not dispute that Powers sent standard-set epoxy. Though there is no documentation that it was intended specifically for the ceiling, Magladry said the NTSB accepts Powers's assertion on that point. The trouble, he said, is that Powers officials at the time failed to even raise the obvious possibility that a mix-up might have occurred.
Magladry said the NTSB still has not figured out how the fast-set came to be used in the ceiling. He said it was possible a construction worker simply picked up the fast-set, already on site for use in the walls, when beginning the ceiling work. He said there was no reason for workers or their Modern Continental supervisors to be aware of any difference between the two types of epoxy.
Powers, however, was intimately familiar with the differences in their two products: In 1995 it conducted tests that revealed the fast-set epoxy lacked long-term strength necessary for use in the ceiling, Magladry noted.
"It's possible Powers sent the wrong representatives to Boston because those representatives were not aware of creep," he said, referring to the October 1999 meeting.