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2006 FIN – Fastener Applications Scrutinized in Boston’s ‘Big Dig’ Collapse

July 25, 2006 FIN – Investigators in the fatal collapse of concrete ceiling panels in one of Boston’s “Big Dig” tunnels are focusing on the potential faulty application of the epoxy used to anchor the bolts. There has been no indication that a “bolt failure occurred, as some TV broadcasts dubbed it.

Massachusetts Gov. Mitt Romney held a press conference with detailed diagrams to illustrate what investigators believe caused the collapse, which could lead to involuntary manslaughter charges.

“In grabbing a hold of these bolts and pulling on them with excess force, they’re letting go a lot earlier than they should have,” Romney explained. “When I say earlier, they’re letting go at lower pressures than they were designed to handle and that suggests that this epoxy system is not working the way it had been designed and engineered to work.”

According to the Boston Globe, initial bolt requirements outlined in 1999 required the fasteners to pass pull tests for 6,350 pounds, more than twice the weight of the panels. Following the collapse, pull tests conducted by the Massachusetts Highway Department caused Romney to declare that all of the more than 1,100 epoxy joints in the I-90 tunnel are “unreliable and must be reinforced.

Reopening the closed portions of the tunnel system continues to be delayed by the discovery of more safety concerns, the Globereports. Transportation engineers are now concerned about five massive jet fans, weighing up to 6,200 pounds, suspended above tunnel onramps. At least two of the fans are anchored with epoxy.
Application Techniques Questioned
The Globe reported that “glue on bolts removed from the tunnel roof near the accident site was brittle and cracked, not like smooth glass as it should have been, indicating that the epoxy potentially lacked sufficient compressive strength, possibly from improper application.

While stressing that he has no first-hand knowledge of the fastening system used in the Boston tunnels, Carmen Vertullo, owner of Simply Better Inc. and an instructor with the Los Angeles Fastener Association’s Certified Fastener Specialist training program, explained to FIN that anchor manufacturers use various rigs to ensure that the epoxy is properly mixed, but they cannot control other critical factors such as hole size, cleanliness, timeliness of use, quantity used or condition of the substrate.

“I would expect that it is not a specification or strength issue. Considering the application, there is probably high safety factor in this design,” Vertullo explained.

Evidence released so far indicates the problem with the epoxy most likely occurred during application. Photographs of the bolts in question appear to show that the bolts remained intact even after impact.

In the past few days a Big Dig technician claimed to have witnessed critical bolt failures in the tunnels during the mid 1990s, the Boston Herald reports.

The technician allegedly revealed what the Herald called “shocking” photographs that show workers in the nearby Ted Williams tunnel “using methods to install epoxy bolts that were flagged as problematic by inspectors.”

The technician did not work in the 1-90 tunnel where the fatal collapse occurred, but both tunnels reportedly employ similar epoxy bolt ceiling fasteners.

The photographs, which have not been made public, allegedly show workers applying epoxy to a screen that was then inserted into the bolt hole.

A stern memo written by the oversight firm Bechtel/Parsons Brinckerhoff in 1995 ordered tunnel workers to “stop installation with wire screens,” according to the Herald. The memo emphasized, “this method is not for solid concrete, but for hollow masonry walls.

Other fastening system concerns at the time included “holes being drilled too deep, concerns that cold temperatures could weaken epoxy and that the use of screens was contrary to the epoxy manufacturer’s recommendations,” the Herald reports.

Fastener expert Joe Greenslade of Greenslade & Co. told FIN that he lacked specifics in the Big Dig collapse, but he emphasized that in over 90% of the cases he handles, fastener failures result from improper application techniques, not malfunction.

“It’s frequently the misuse of the fasteners that causes most of the problems,” Greenslade told FIN.

Insufficient Testing Also Alleged
Insufficient testing could also have played a role in the collapse. Investigators are examining test records to see if the contractor tested every bolt, as required by the building contract, the Globe reported. Records indicate pull tests were mandated for all of the nearly 13,800 bolts used in that portion of the tunnel system.

For now, construction crews have begun to reinforce the ceiling with new heavy-load-tested embedded anchors, the Globe reported. The new anchor bolts passed 14,000-pound pull tests. Despite the incident, several fastener industry veterans interviewed by FIN gave a vote of confidence to chemical anchors in general.

“These are very reliable, highly-engineered systems used in critical application, “Vertullo noted. “When used properly, they work well.”

Charlie Carter, an engineer with the American Institute of Steel Construction, agreed that fastening systems using epoxy properly are reliable. Carter told FIN he didn’t have enough information to comment directly on the incident in Boston, but he cautioned against hasty judgments.

The incident is the latest in a string of setbacks on the $15 billion Big Dig tunnel system, the most expensive highway project in U.S. history. In recent months contractors have been accused of delivering inferior concrete after numerous leaks were discovered in some of the concrete walls of the tunnels. ©2006/2012 Fastener Industry News

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2009 FIN � Powers Fasteners’ $100k Fine Concludes ‘Big Dig’ Investigation
September 28, 2009 FIN – Powers Fasteners agreed to plead guilty to one count of making a false statement and pay a $100,000 fine in connection with construction of Boston’s “Big Dig” tunnel system.

The latest charge “alleges that the general contractor … utilized a Powers Fasteners epoxy product, Power Fast Epoxy, to secure the drop ceiling to the roof of the tunnel using anchor bolts epoxied into drilled holes,” according to the Attorney General’s office.

“Several of the anchor bolts ultimately failed, and on July 10, 2006, several ceiling panels collapsed on a vehicle, killing a motorist.”

Earlier this year Powers Fasteners agreed to pay $16 million in exchange for one count of manslaughter being dropped against the company.

Brewster, NY-based Powers Fasteners was charged in 2007 with manslaughter in the death of Milena Del Valle, who was crushed when the tunnel collapsed. The company, which manufactured the epoxy blamed for the collapse, reached a $6 million settlement with the woman’s family.

In addition to the financial settlement, Powers Fasteners reportedly agreed to recall its “fast-set” epoxy used in the tunnel that collapsed, as well as notify customers that the epoxy failed certain tests and is not recommended for sustained loads.

Authorities claim Powers “failed to disclose (the difference between its Fast and Standard Set epoxies) in its published Design Manual in 1999, which was relied upon and submitted by the general contractor … for approval.”

Company president Jeffrey Powers told FIN the settlement was in the best interest of his company. “After years of exhaustive investigations by government officials in Massachusetts, we agreed today to end the final investigation by paying $100,000 and accepting a technical charge involving a ‘false statement by omission’ in a Company marketing brochure,” he stated.

Jeffrey Powers told FIN that in 1999, unbeknownst to Powers, a small section of a company brochure – a 1997 printing –was used by Modern Continental in a preliminary submittal to Big Dig Tunnel officials as part of their effort to seek permission to use epoxy to suspend the ceiling that ultimately collapsed. This brochure did not distinguish between fast setting and standard setting epoxy with respect to long term sustained loads.

“However, one month later and before the Big Dig Tunnel ceiling construction even began, Mass Highway, the owner of the tunnel, was advised of the differences between fast setting epoxy and standard setting epoxy after a Powers engineer disclosed that Powers Fast Set could not pass the AC-58 – a creep test,” Jeffrey Powers explained.

“Ultimately, the submittal that was approved for the ceiling construction did include an engineering report, provided by Powers, which clearly disclosed that Fast Set Epoxy was approved for short term use only and that Standard Set Epoxy could be used for long term loads.”

He said this ICBO engineering report was widely distributed by Powers beginning in October 1999.

Jeffrey Powers added that the conclusion of the investigation “confirms that no individual Powers employee, past or present, engaged in any knowing misconduct.”

The case was investigated by the Department of Transportation Office of Inspector General and the Federal Bureau of Investigation. ©2009/2013 Fastener Industry News

For information on permission to reuse or reprint this article please e-mail: FIN@GlobalFastenerNews.com