TBM Arrives at $360M Manchester Stormwater Tunnel Site Ahead of August Launch
A 281-ton tunnel boring machine has arrived at the $360 million Cemetery Brook Drain Tunnel project site in Manchester, N.H., with crews now testing and assembling the machine ahead of an August launch, ENR reports.
Market Impact
The TBM, nicknamed Granite Janet, arrived from Germany in early June but was delayed at the Portsmouth, N.H. port due to permitting requirements for the oversize load, according to Jacob Blunden, project manager for Methuen Obayashi, the contractor on the job. Bay Crane Cos. moved the disassembled machine using a 450-ton crane and a 65-ft self-propelled modular transporter, then lowered it into the launch pit with a 700-ton mobile rough terrain crane on June 18.
The project, which launched in 2025, is about 25% complete overall and 35% complete on cost, including the TBM itself, Blunden says. Ed Pietrasz, resident engineer for construction manager Parsons, says the team is running extensive component testing, including bentonite slurry checks, centrifuge and pump tests, and electrical systems, before mining begins. “We’ll test every single component before they push it into the tunnel,” Pietrasz says. The TBM will be built out with 16 gantries attached one at a time due to site space constraints near the Merrimack River, each supporting slurry pumps, water lines, compressed air and other equipment. Roughly 80 workers report to the site daily, which also requires coordination with CSX, since mining runs through railroad property requiring separate material testing to avoid contamination.
What It Means for Subcontractors
- Excavation support and slurry system crews should expect ramp-up activity through the coming weeks as testing and commissioning continue before the August launch, including bentonite slurry mixing, centrifuge operation, and pump/shaker sifting systems.
- Dewatering and slurry treatment subs have an active scope on-site now: the slurry treatment plant mixes bentonite, water and additives, pumps it to the cutterhead, and recycles it through a loop system, meaning ongoing demand for slurry handling and treatment support as mining ramps up.
- Crane and heavy-haul contractors should note the logistics model used here, a 450-ton crane, a 65-ft self-propelled modular transporter, and a 700-ton mobile crane, as a reference point for bidding similar oversize TBM moves near rail corridors or river crossings.
- Environmental and materials-testing subs working near rail lines should budget for CSX-driven segregation and contamination testing protocols, since muck removed from railroad property must be tested to separate parameters before disposal.
- With the project at 25% overall completion and 35% cost completion as of this report, subs eyeing downstream packages (electrical, mechanical support, muck haul-out) should track Methuen Obayashi’s schedule closely as the August mining launch approaches.
