Big Dig job may have used wrong epoxy

Contractors apparently used the wrong adhesive to install at least some of the bolts in a Big Dig tunnel ceiling that partially collapsed last summer, project records show, prompting criminal investigators to focus on whether the mix-up was a significant factor in the accident that killed a Jamaica Plain woman.

Invoices from the 1999 ceiling construction job show that Modern Continental Construction Co. received and apparently used at least one case of a quick-drying epoxy to secure ceiling bolts to the tunnel roof rather than standard epoxy, which the ceiling designers had specified.

The distinction was crucial to the safety of the ceiling: The "fast-set" epoxy holds 25 percent less weight than standard epoxy and is not recommended for suspending heavy objects overhead.

It is unclear how widespread the use of fast-set epoxy was, since most sales records don't list the epoxy type, but state criminal investigators are looking seriously at the possibility that the weaker epoxy was used in the ceiling section that collapsed when 20 bolts popped out on the night of July 10, 2006, according to representatives of several firms under investigation.

The investigators also want to know why no one raised the possibility that the wrong epoxy had been used when ceiling bolts started coming loose during construction of the Interstate 90 connector tunnel.

"If [workers] used the wrong stuff, which appears to be the case, the issue is who knew about this or were they reckless about letting the project go forward with the wrong stuff?" said a consultant to one of the firms involved in the ceiling project, who asked not to be named so as not to anger prosecutors who are presenting their evidence in secret to a Suffolk County grand jury.

Paul F. Ware, the special prosecutor leading the state's criminal investigation, has sent investigators back into the tunnel over the last few days to collect more ceiling bolts for lab analysis, according to a letter from the Massachusetts Turnpike Authority, which manages the Big Dig tunnel system, to the companies involved in the ceiling project. The tests could help investigators determine the strength and type of epoxy that was used.

Use of fast-set epoxy in the ceiling is one in a series of missteps that may have contributed to the accident and, at the least, point out oversight lapses in the $14.6 billion Big Dig project.

The Globe has previously reported that, to save time, Big Dig managers and designers eliminated half the ceiling bolts called for in the original ceiling design and that construction workers made numerous mistakes during installation of the bolts that could have weakened them. The newspaper has also reported that ceiling bolts in the area of the collapse were safety-tested with a weight now regarded as too low, potentially allowing defective bolts to pass.

If the bolts were held in place by fast-set epoxy, the ceiling would have had little, if any, margin of safety left. Bolts secured with fast-set epoxy could safely carry 4,285 pounds each, rather than the 6,350 pounds the designers had planned on, based on their final report to Big Dig managers on the ceiling. Two independent engineers who have reviewed the ceiling's specifications for the Globe estimated that the ceiling's weight was close to 5,000 pounds per bolt, which is more than bolts secured with fast-set epoxy were designed to bear over the long term.

After the accident, the tunnel ceiling was permanently removed in the area of the accident, and elsewhere in the connector the ceiling was reinforced with additional bolts and brackets.

Construction of the ceiling was supervised by engineers at the joint venture of Bechtel and Parsons Brinckerhoff, but responsibility for using the right epoxy is difficult to pin down. The Braintree office of Gannett Fleming designed the ceiling to be secured with standard epoxy, but that require ment is not highlighted in project documents. Modern Continental built the ceiling, but workers have said they weren't told there was an important difference between the epoxies. Powers Fasteners of New York had a contract to supply the epoxy and bolts, but only through a small distribution company that bought the products wholesale and then delivered them to the job.

As a result, each company has said it bears no responsibility for use of the wrong epoxy. In fact, Powers Fasteners officials have told investigators that they aren't even certain that the epoxy in the accident area was their product, even though, during construction, company officials visited the tunnel and provided technical advice to workers on how to install the ceiling bolts properly. Powers' distributor, Newman, Renner, Colony of Plymouth, declined to comment.

The investigation into what epoxy was used has been hampered by both the imprecise sales records and the difficulty of chemically identifying the epoxy used in the area of the accident. The National Transportation Safety Board reported four months after the crash that it could not identify the epoxy taken from the failed bolts even after comparing it with samples of standard and fast-set epoxy. And the sales records that show what Newman, Renner, Colony delivered to Modern Continental distinguish between standard and fast-set epoxy in only one invoice.

State investigators in recent months have intensified their interest in Powers, sending company officials a fresh subpoena in March asking for documents concerning its role in the ceiling project. In addition, witnesses from other companies called before the grand jury hearing evidence in the case say they are being questioned closely about the type of epoxy used to hold up the ceiling.

"All the discussion outside the jury room is about the question of which epoxy was used and was it fast-set epoxy?" said an official for one of the companies under investigation who asked not to be named.

The focus on epoxy comes as Ware and his boss, Attorney General Martha Coakley, strive to meet a self-imposed deadline of June to decide whether to ask the grand jury to return indictments against anyone for criminal negligence in the accident. Legal analysts say that winning a conviction would require Coakley to prove that people or companies knew they were building a dangerous ceiling or they were so reckless that they missed obvious warning signs.

Before taking office in January, Coakley had raised doubts that the evidence was strong enough to prove criminal negligence, but, since Ware's arrival on March 1, some in her office say they have become more optimistic that there could be enough evidence for criminal indictments.

But fixing responsibility for the epoxy remains challenging, in part because the design documents produced by Gannett Fleming and Bechtel/Parsons Brinckerhoff say only in passing that contractors should use standard epoxy rather than fast-set for ceiling bolts. All of the safety calculations are based on bolts secured by standard epoxy, but the design specifications don't explicitly forbid fast-set, and the fact that fast-set can support less weight than standard epoxy is contained only in a footnote.

Adding to the confusion, although fast-set epoxy cartridges were clearly marked, the workers installing the ceiling may not have known there was a difference between fast-set and standard aside from drying time. Construction workers on the ceiling project have said they used Powers Fasteners epoxy and bolts, but they don't recall whether the label said fast-set.

Finally, the epoxy passed through many hands on its way to the tunnel. Sika Corp. manufactured the epoxy at a plant in Ohio, then shipped it to a warehouse in New Jersey in barrels marked with a prominent "FS" to denote fast-set epoxy, according to Sika officials. Powers then transported Sika's epoxy to its plant in New York where workers repackaged it into small cartridges, placing Powers's label on it. Then, Newman, Renner, Colony brought the cartridges and bolts to Modern Continental at the tunnel site.

Criminal investigators are focusing on a period in October 1999 when five ceiling bolts came loose shortly after the ceiling was hung from them, prompting Modern Continental officials to call in Powers Fasteners officials for advice. Over the next three months, officials from Powers, Modern and Bechtel/Parsons Brinckerhoff discussed ways to install bolts more securely, but there is no evidence anyone asked: Did workers use the right epoxy?

As one lawyer with direct knowledge of the investigation put it, "Was the right advice given by the experts?"

Allen can be reached at allen@globe.com; Murphy at smurphy@globe.com.