Granite Janet, a 281-ton TBM, arrived on an oversize truck in a parking lot next to the Queen City Bridge in Manchester, NH late last month as crews on the $360 million Cemetery Drainage Tunnel project prepare to break ground in August.
Bay Crane Cos. transferred the disassembled TBM from a 139-foot truck and trailer to a 65-foot self-propelled modular conveyor using a 450-ton crane, then hauled it over CSX railroad tracks to the launch pit where a 700-ton mobile crane lowered it, says project manager Jacob Blushi Methuden O. It started last year and remains on budget and on schedule.
On the morning of June 18, Bay Crane Co. used a 450-ton crane to pick up a section of the TBM on the self-propelled modular conveyor that transported it to the launch pit.
Courtesy of Edward Pietrasz, Parsons
The TBM shipment arrived on time from Germany in early June, but was delayed at its port of arrival in Portsmouth, NH due to clearance requirements for traveling with the oversized cargo, Blunden says.
The project, which began in 2025, is about 25 percent complete overall and has reached 35 percent cost completion, including the TBM face, Blunden says,
In Manchester, when a manhunt after a shooting left two public workers injured on the morning of June 18, crews posted a sheriff at the entrance and work continued, says Parsons resident engineer Ed Pietrasz, the project’s construction manager. “I got there at a quarter to six and the cutter came in at about 10 in the morning,” he says.
At the CBDT project’s slurry treatment plant, bentonite and water are mixed with other additives transported as a pressurized liquid to the cutting head to prevent the soft soil from collapsing. It removes sludge and debris and sends the fresh slurry through the plant’s loop system.
Photo by Johanna Knapschaefer for ENR
With the assembly of the TBM still ongoing, testing and commissioning will take place in the coming weeks before launch. “We are testing certain systems as they are completed,” says Pietrasz. “If something is put together and it doesn’t work, we don’t want to find out when it’s 100 meters down the tunnel,” says Pietrasz. “We’ll test each component before they push it into the tunnel.”
Piece by piece, the team is running a myriad of tests, including testing the water to see if the TBM can contain bentonite slurry for machine operation, the slurry centrifuge used to treat mud and operating equipment, pumps and agitators that act as a sieve that sifts rock and debris during mining, and conducting electrical tests. “Everything has to work before mining,” says Pietrasz.
The TBM will include 16 gantries that will be connected one by one due to space constraints at the site’s location near the river. The gantries, each with a specific purpose, will support the TBM with slurry pumps, water, compressed air and other equipment, moving 20 to 30 feet over weeks.
Photo by Johanna Knapschaefer for ENR
Coordinating with CSX is another important part of the job at the site where 80 workers report daily. “We’re mining through their property and with the different materials that come through, they have separate testing parameters to make sure there’s no contamination from the material we’ve taken from their property,” Pietrasz says. “That’s why we have to separate its mud and test its parameters.”
