Water gushed into the Central Artery's northbound tunnel for hours yesterday from a small breach in the eastern wall, backing up afternoon rush-hour traffic for miles and leaving Big Dig officials at a loss to explain where the water was coming from and what had caused the leak.
Water gushed into the Central Artery's northbound tunnel for hours yesterday from a small breach in the eastern wall, backing up afternoon rush-hour traffic for miles and leaving Big Dig officials at a loss to explain where the water was coming from and what had caused the leak.
In the first couple of hours after the leak was reported, about 1:45 p.m., officials closed two lanes in the northbound tunnel and all onramps from the Massachusetts Turnpike. Traffic on the Southeast Expressway backed up to Quincy, and there were long delays on the turnpike approaching the interchange.
Big Dig officials said at a late afternoon press conference that they hoped to reopen all the tunnel's northbound lanes by this morning's commute. But they said they did not know how long it would take to find the source of the leak and repair the damage, and they could not guarantee that work would be finished in time.
By late afternoon, officials could not provide an estimate of how much water had flowed into the tunnel. For safety and to soak up the water, highway workers piled sandbags along the eastern wall and poured sand in the right lane.
Officials and engineers were so uncertain about the origin of the water that some tasted it. The likely source, they said, was groundwater, because that portion of the tunnel sits 110 feet underground.
One theory for the leak was that sand or clay got into the poured concrete in the tunnel's slurry wall during construction, said Sean O'Neill, a spokesman for the Massachusetts Turnpike Authority, which oversees the $14.6 billion Big Dig project.
O'Neill said it is possible that groundwater ate away at the sand and carved a small leak in the wall.
During construction of the Big Dig, engineers and workers built the slurry walls by first digging a series of deep trenches, which were filled with a clay substance. Concrete was then pumped underneath, displacing the clay and forming the tunnel's concrete walls.
Keith Sibley, director of construction for Bechtel/Parsons Brinckerhoff, the consortium responsible for major portions of the Big Dig, sought during the press conference to reassure drivers and state officials that there were no safety concerns.
"Structurally, there's no problem with the tunnel at all," he said.
But state officials said they would hold the consortium responsible for all costs of sealing the leak and repairing the wall.
"Believe me, as a customer of the product we constructed, I'm not happy right now," said Matthew J. Amorello, chairman of the Massachusetts Turnpike Authority, which oversees the $14.6 billion Big Dig project. "It's unacceptable, and we're going to deal with it."
Bechtel/Parsons officials said last night that Modern Continental, the contractor that built the tunnel's slurry walls 10 years ago, would pay for the repairs.
"Modern Continental has accepted responsibility and will make all the repairs as quickly as possible," said Andrew Paven, a Bechtel/Parsons spokesman.
But last night, a spokeswoman for Modern Continental said that no such agreement had been reached. "The cause of the leak has not been determined, and no conversation about the cost of the repairs has taken place," said the spokeswoman, Lorraine Marino.
About 7 last night, Big Dig engineers met in a office at the project's headquarters on Kneeland Street to figure out how to plug the hole without making the problem worse. The engineers said that removing tiles along the wall could expand the leak. But crews dismantled a section of the wall late yesterday to try to make repairs.
Officials were notified about the leak when motorists began reporting water seeping through Jersey barriers along the northbound tunnel's eastern wall.
Shortly after those reports, with the water flow at its heaviest, officials closed two lanes of the northbound tunnel, which produced the miles-long backup.
To ease congestion, officials opened the Haul Road off Interstate 93 north at 3:30 p.m., a road normally limited to commercial traffic. At the same time, they closed the entrance into the tunnel from Congress Street. And 15 minutes later, officials closed all onramps from the turnpike leading to northbound tunnel.
By early evening, the closing was reduced to one lane, and traffic was flowing. So was the water, which continued to form a small pool in the right lane of the tunnel about a quarter mile south of Exit 23 to Government Center.
A stream of water trickled between sandbags and rippled in a puddle about 5 inches deep and two cars long in the right lane.
Officials said they found an 8-inch hole in the slurry wall, one of the Big Dig's signature innovations, and sent a special team of construction workers to inspect whether the damage was more extensive.
Officials said there was no connection between yesterday's leak and a water leak last winter, when ice formed on the road surface in the northbound and southbound tunnels. The ice was blamed on old steel footings from the elevated Central Artery, which allowed rainwater to seep into the tunnel.
While construction of the Big Dig is nearing an end, the process for determining who should pay for the cost overruns in the project is ongoing.
In February 2003, Amorello appointed Edward M. Ginsburg, a retired state judge, to lead a review of the project with an eye to holding contractors responsible for mistakes. To date, Ginsburg's team of lawyers and engineers has identified more than 700 construction issues and has recovered $3.5 million from a design firm.
The Ginsburg team has filed several lawsuits against other design firms, including one seeking $150 million from Bechtel/Parsons Brinckerhoff, the project's overall manager.
Last night, Ginsburg said he could not comment on the leak, but promised an aggressive investigation on behalf of taxpayers.
"We will definitely get all the preliminary reports and send our people in to look at this," he said. "This shouldn't happen, and somebody has got to make an explanation, and I can assure you it is not going to get by us. We will look at this, absolutely."
By David Abel and Mac Daniel. Sean P. Murphy of the Globe staff contributed to this report.
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© 2004, The Boston Globe. Distributed by Knight Ridder/Tribune Business News.
