Bechtel/Parsons Brinckerhoff Testifies in Boston About Big Dig Tunnels
MacDonald began with prepared remarks (below), after which the state senators and representatives comprising the committee engaged the four in questions and answers.
As prepared for delivery
Massachusetts State Legislature
Joint Transportation Committee
Statement by John MacDonald
Chairman, Board of Control, Bechtel/Parsons Brinckerhoff
December 2, 2004
Good morning. Thank you for this opportunity to appear before the joint committee.
I am John MacDonald, Executive Vice President of Bechtel Corporation and Chairman of the Bechtel/Parsons Brinckerhoff Joint Venture Board of Control since mid-2001. I would like at this time to introduce three of my three colleagues who will join in answering your questions. [Morris Levy, Matt Wiley, Keith Sibley]
We are here to address concerns about tunnel leaks at the Central Artery/Tunnel Project, also known as the Big Dig. Specifically, we will discuss the September 15 slurry wall breach and the separate and distinct issue of water intrusion.
As Management Consultant for the Big Dig, we take these issues seriously. As always, we are committed to fulfilling our responsibilities and delivering a quality project. We also believe the public deserves factual information about the safety and condition of Boston's highways.
First, let me respond to the breach in the northbound I-93 tunnel wall that backed up traffic on September 15 of this year.
Our investigation to date indicates that we missed two opportunities to correct the specific wall problem ahead of time. We seriously regret not doing enough to prevent this incident. There is no satisfactory explanation for this.
We acknowledge our responsibility and will pay our fair share of the cost of permanently fixing this portion of the wall. We are also working vigorously with our own and independent experts to ensure that similar problems do not occur elsewhere.
Unfortunately, there is widespread confusion of the wall breach - a construction error - with the many small leaks that are normal and expected in tunnels that are still under construction. As a result, fears have been raised about tunnel safety and the timetable and cost of repairs.
In fact, the tunnels are safe. The tunnels are solidly built, and the program to seal leaks should be substantially complete next summer, without jeopardizing the Big Dig's budget or schedule. We have at all times worked closely with state and federal officials to implement this program.
The September 15 wall breach
Returning to the September 15 wall breach, we and the state have carefully investigated what happened. It was caused by improper construction of a single wall bay where work by two contractors came together.
The construction contractor failed to follow his own approved procedures, which called for removing an end stop and clearing away dirt and debris trapped by overflow concrete in their section of the wall. This pocket of material (clay intrusion) eventually allowed water to find a path through the wall and into the tunnel, closing two lanes for several hours.
Our field engineer noted the construction defect in 1999 but apparently approved it and did not follow up with recommendations for corrective action.
The contractor identified a leak at the wall location in late 2001 and informed project representatives. Days later, our resident engineer called on the contractor to undertake non-destructive testing to assure that the wall panel met contract specifications, and to submit a procedure for repair.
Over the following year, project officials engaged with the contractor, seeking remedial work on slurry wall locations identified in walk-down inspections.
On February 28, 2003, the contractor advised by letter that required remedial work to all slurry walls had been completed. However, the contractor did not take proper steps to fix the so-called inclusion that weakened the wall bay where the September breach occurred.
Although responsibility lies with the contractor to ensure proper performance of the wall, we seriously regret that we did not do more to prevent the September incident. We should have caught the problem with the construction of this panel during the initial inspection. Later we should have been more vigilant in making the contractor carry out necessary tests and repairs properly.
The cost of any repairs will be assumed by the responsible parties, not by the project or the public. Again, we acknowledge our responsibilities and will be among the parties that share the cost.
The conditions that led to the breach were extremely unusual - improper construction, poor soils, great water pressure at the deepest portion of the tunnel, and a breakdown in the inspection and acceptance procedures normally applied on the project. To eliminate the possibility that similar issues might arise elsewhere, project teams are conducting extensive physical inspections and a thorough review of records. We have added personnel at our own expense to expedite this process. In addition, we and the state have each hired independent
experts to ensure the effectiveness of this review process. We have made our records available to them. This process will continue for several weeks.
In the course of this analysis, we have identified seven other wall bays that may also need remedial work, although not as extensive as the panel involved in the September breach. They, too, will be repaired at no cost to the public or to the project. Our primary goal is to complete the review and complete all repairs as soon as possible.
Because the Big Dig has recently achieved so many milestone openings, many people have lost sight of the key fact that the tunnels are still under construction. We still have $400 million of further project construction ahead of us.
No one should be surprised that some water is entering the tunnels while they remain partially open to the weather. For instance, water flows down traffic ramps that are still uncovered. Some roof sections have yet to be installed. There are open holes where beams that supported the old elevated artery once stood. Manholes and utility conduits must remain unsealed until final cabling is installed.
Covering or sealing such pathways is a scheduled part of finishing the project. While the project progressed, the Central Artery could not be closed to huge daily traffic flows. That meant opening the tunnels to traffic - safely - long before they were finished. Only then, in the complex staging process to keep the city open, could we bring down the elevated artery, remove the artery supports, and finally close up the tunnels.
Fortunately, the end is in sight next year. In the meantime, water entering the partially opened tunnels is readily managed by permanently installed drains and pumps. They have far more capacity than needed to handle the load.
As George Tamaro noted Tuesday, all tunnels built below the water table have some seepage, even when complete. In Boston alone, leaks can be observed in such underground projects as the Red Line, North Station, Port Office Square, and the recently opened Seaport Hotel Garage.
In order to reduce leakage to minimal levels, Big Dig contractors applied waterproofing materials to the tunnel floors and roofs, where joints create opportunities for water intrusion. The waterproofing materials and techniques were all standard in the industry and were selected by the contractors.
As the project gained experience with local conditions and with materials performance, waterproofing processes were upgraded over time, in order to use those best suited to contractor skills and specific conditions found on the project.
The basic waterproofing design of the tunnels is sound - as demonstrated by the fact that the majority of wall bays show no sign of leakage. But as a B/PB "Waterproofing Concept Report" noted in 1990, "Waterproofing is seldom installed under ideal conditions, and, with or without waterproofing, all tunnels experience some leakage. For this reason, leakage control is a continuing maintenance effort."
Sealing leaks and seeps
Detecting and sealing inevitable leaks through walls and joints is an integral part of the normal construction process. It takes persistence and patience to block the multiple paths that water under pressure always finds or creates.
To organize the process, we formed a task force with state and federal officials in 2000. Spots where water enters are systematically located and sealed with grout, by the contractors responsible for each of the various sections of the tunnels or utilities.
As both George Tamaro and Jack Lemley confirmed Tuesday, the grouting program is working and should be continued. The program has already made substantial progress. The number of leaks has been cut by two-thirds. The two tunnel segments that have the longest experience with the grouting program, 11A1 and 15A1, have already achieved the watertight specification required to transition from construction to operation.
Based on this progress, and plans to augment the number of crews, the leakage control program will take months, not years, to complete. It should be finished along with the balance of construction in fall 2005. It does not jeopardize the project schedule. The work will generally be done at the contractors' expense.
Let me very clear on one additional point-the disclosure of information regarding leak mitigation.
Since the inception of this project, with respect to these issues and all others, Bechtel/Parsons Brinckerhoff has shared with its customer all documents, information, and advice concerning our work on the Big Dig. Assertions to the contrary are simply untrue.
Even after the tunnels are complete and existing leaks are sealed, some new seeps will appear over time. They will be detected and sealed as part of a normal maintenance program, as with all tunnels.
According to the Federal Highway Administration, tunnels typically experience continuing seepage about equal to the flow from one ordinary garden hose for each mile of tunnel. The Big Dig's tunnels already meet this norm for fully finished tunnels. When completed next year, the Big Dig tunnels will perform better than the industry norm.
Safe and secure
These dwindling leaks represent no threat to the integrity of the Big Dig tunnels. Our inspections show no sign of structural corrosion. As the MTA's independent consultants George Tamaro and Jack Lemley have stated, the tunnels are safe and structurally sound. We strongly share this assessment. The people of Massachusetts can drive the Big Dig tunnels with assurance.
Our goal is to complete this project as quickly and cost effectively as possible and provide the citizens of the Commonwealth with a transportation infrastructure system that will serve their needs through the 21st century.
It has taken the most complex urban engineering and construction project in U.S. history to bring that end in sight.
The Big Dig faced the extraordinary requirement of keeping Boston running while building a multi-lane, federal interstate highway underground - without disrupting traffic, undermining existing subways and utilities, or endangering building foundations.
This requirement was likened by one former project director to performing open-heart surgery on a patient who insists on playing tennis at the same time.
We didn't find the necessary solutions in textbooks. Even with application of the most advanced engineering skills, it was not always possible to fashion solutions perfectly the first time.
Complex engineering design and construction is a process of identifying and overcoming problems as they arise, and adopting new technologies and materials as they become available.
Our dedicated employees are proud of the role they have played in finding such solutions to improve local transportation and reshape Boston's waterfront and downtown business district.
We appreciate the opportunity to address these issues. We are happy to answer any questions.
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