Four former managers working on the Big Dig project in Boston were found guilty of conspiracy and fraud charges this week.
In total six former managers of Aggregate Industries, which was working on the highway project in the city, were indicted in 2006 on charges that they falsified records hiding the fact they had delivered more than 5,000 truckloads of inferior quality concrete.
The six were accused of recycling concrete that was too old or already rejected by inspectors and instead provided substandard concrete to the project.
Last month, two of the managers pleaded guilty, but now four others Robert Prosperi, of Lynnfield, Mark Blais, of Lynn; Gregory Stevenson, of Furlong, Pa, and John Farrar, of Canterbury, Conn have been convicted.
In a statement, Aggregate said: “While we regret that these former employees have been found guilty, the jury has spoken and it would be inappropriate for us to second-guess them.
“It is important to note, however, that the evidence at trial once again showed that the concrete provided by Aggregate Industries Northeast to the Big Dig was both safe and strong.”
The firm pleaded guilty to fraud charges in 2007 and paid a $50 million settlement to bring criminal and civil inquiries to an end. Aggregate managed to have avoid debarment as part of the agreement, otherwise it could not have bid for state and federal contracts.
The $15 billion Big Dig tunnel crosses Boston Harbour en-route to Logan Airport and was plagued by construction problems, leaks, falling debris and huge cost overruns.
Ten 3t reinforced-concrete ceiling panels plunged onto a car travelling through the Big Dig’s Interstate 90 connector tunnel on 10 July, killing a passenger, but the case against Aggregate has not been linked to this accident
An investigation following the incident found that epoxy grouted steel anchors from which the ceiling panels were suspended had pulled from their sockets.
The 16mm diameter anchor bolts had been grouted into holes cored from the tunnel’s reinforced concrete roof. Steel hanger rods connected to the bolts supported the panels.
Further investigation showed that more than 250 additional epoxy-grouted anchors had moved.