Early preparations have begun for a major water infrastructure project that is expected to take 14 years to complete.
Needham is one of seven communities that will be impacted by construction for Massachusetts Water Resources Authority’s Metropolitan Water Tunnel Program — a program that will add two new water supply tunnels to a system that provides more than 3 million people across eastern Massachusetts with clean drinking water.
Although the project is two years out from its official start date, MWRA confirmed in an Aug. 11 meeting with Needham’s Select Board that prep work will begin in earnest this coming spring.
Tunnel preparations to-date include a closed-circuit television condition assessment of utilities in proximity to the project site, test borings to study subsurface conditions, and electrical upgrades from Eversource that will support tunnel boring operations. Conversations now center around construction of a dewatering drainage line, set to begin in spring 2027 and last through spring 2028.
In the South tunnel, 1,250 feet of 36-inch pipeline will be installed as a permanent drainage system for groundwater that will seep in during construction. The pipeline will run underground from I-95 to the Charles River, through Brook Road, Arlington Road and Charles Street.
Near I-95, the drainage system will be built through a trenchless construction method called pipe jacking, which uses special machines to push pipes through the ground from a launch shaft to avoid heavy digging and traffic disruption.
“We are anticipating this work will be done during the day,” said David Abt, design manager for the tunnel department.
The rest of the system will be installed through cut and cover construction: digging a trench, building a structure inside it, then backfilling to restore soil on top.
“We will construct this in stages to reduce our footprint and our impact on the surrounding area, with discussions between DPW, engineering and the police,” Abt said. “And given it’s a dense commercial area, we think night work would be the least impactful to abutters,” he explained of the pipeline portion running beneath Needham streets.
The crew will also replace the town’s aging clay pipe sewage systems that cross over with the new drainage system. Paul Savard, acting director for the tunnel redundancy program, added there will be no sewer service interruptions for customers downstream of the work.
Select Board chair Heidi Frail voiced concern around the project’s potential impact on Needham residents.
“This is a reasonably small area, both with commercial customers and residential neighborhoods just outside the perimeter,” Frail said. “I’m not really sure on the scale of disruption these machines will cause.”
“It’s typical pipeline construction in the streets,” Savard responded, noting the majority of construction abutting residential neighborhoods and commercial businesses will happen at nighttime to ensure minimal disruption.
Savard termed the pipeline and similar prep projects “early enabling work,” or pieces of construction that need to be done ahead of the large tunnel construction.
The 15 miles of deep, hard-rock pressure tunnels will add redundancy to the Metropolitan Tunnel System, intentionally duplicating important parts to avoid service interruptions and system shutdowns when future maintenance needs or emergencies come up.
The water supply system has operated without a backup since the Quabbin Reservoir was completed in 1939.
“There are a couple incidences that happened in the past, back in May of 2010 and more recently in 2024, that brought [to our attention] the need for redundancy to the city tunnel system,” Savard noted to the Select Board, adding the tunnel program was prompted by a water main break in 2010 that resulted in a boil water order.
“The main point here is that we want to make sure we provide uninterrupted delivery of our high-quality water to the communities that we serve, at any time of the year, without any service interruptions,” he said.
The tunnels will begin in Weston on I-90 and I-95. The North tunnel, expected to be 5 miles long, will end in Waltham. The South tunnel, expected to be 10 miles long, will end in Mattapan. Needham will be directly affected by the longer South tunnel, which will be constructed with tunnel boring machines based at the I-95 Highland Avenue interchange. Two large shafts will be created via controlled blasting to lower the boring machines underground.
“When that tunnel gets constructed, all the material that comes out gets loaded onto trucks and taken away,” said Savard.
Needham’s proximity to the highway will enable construction trucks to rotate through more easily with excavated materials from tunnel construction.
Notices have been and will continue to be distributed to abutters as the MWRA tunnel project progresses.
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