
The state Energy Facilities Siting Board gave tentative approval Monday to the huge project to build an electric substation 11 stories underground in Kendall Square and connect it with 8.3 miles of underground cables to existing substations in East Cambridge, Somerville, Cambridgeport and Brighton. The tentative decision rejected a proposal by the Massachusetts Institute of Technology to change one of the cable routes chosen by electric utility Eversource.
The 226-page ruling, though not final, is an important step in completion of the project, which Eversource says is necessary to handle rapidly rising demand for power in Cambridge and surrounding communities because of new development, and to transition to electric vehicles and heating and cooling systems in response to climate change.
The new substation, the first of its kind in Massachusetts and one of the few underground facilities in the United States, will cost an estimated $714.6 million for the equipment; the cost of the land and underground vault wasnโt given in the decision but a deal between Cambridge and property owner BXB will save money, the board said. The underground cable routes approved by the board will cost an estimated $600 million.The estimated cost to ratepayers for the entire project over 40 years, after discounting the amount back to the 2029 date when it will be completed, is $2 billion, according to Eversource filings with the board; the impact would be shared by all 1.8 million customers over the 40-year life of the project.
The siting board has scheduled a hearing at 9 a.m. June 27 to discuss its tentative decision. The event will be held on Zoom and in person at the Department of Public Utility office at One South Station in Boston.
Asked to comment, spokespersons for Eversource and its ally on the project, the city of Cambridge, gave low-key endorsements of the decision. โWe appreciate the [siting boardโs] thoughtful consideration and approval of this critical energy program with the release of the tentative decision and look forward to continuing our ongoing collaboration with local stakeholders,โ said William H. Hinkle, of Eversource. โOur work together to make this project a reality will help lead the way in ushering in our unprecedented clean energy transition.โ
Cambridge spokesperson Jeremy Warnick said: โThe city of Cambridge appreciates the thoughtfulness and thoroughness that the Energy Facilities Siting Board has committed to this critical project. While this is a lengthy decision that is still being reviewed, the city of Cambridge supports the draft decision approving the preferred alternative routes developed by Eversource in close collaboration with the city.โ
As for the Massachusetts Institute of Technology, spokesperson Kimberly Allen said: โMIT respects the EFSB-led process and is carefully reviewing the tentative decision.โ At a Cambridge City Council Health & Environment Committee hearing on the project Nov. 21, Joe Higgins, the schoolโs vice-president for campus services and stewardship with responsibility for construction, said it would not appeal a siting board decision.ย
The committee and later, the full City Council, voted to ask MIT to withdraw its proposal.
Risk of delay
The university had stunned participants in the board proceedings on the eve of hearings last October by proposing an alternate underground cabling route between the proposed substation and the Charles River that would have avoided running wiring down Vassar Street. MIT said the street already had myriad underground connections between its facilities and constituted the โheartโ of the campus. The university proposed to use the Grand Junction railroad, Albany Street, Massachusetts Avenue and Main Street instead.ย
The city and Eversource said they feared that giving full consideration to the MIT route would delay a decision. They also said the alternate route had flaws that would make it impossible to build. Eversource said the school hadnโt ever said it intended to submit an alternate route proposal during three years of meetings to map out cable routes.
The university denied those criticisms and submitted evidence that it said showed its route was better than the Vassar Street option โ using Eversourceโs own scoring methodology.
Not โclearly superiorโ
The siting board rejected MITโs arguments and supported Eversourceโs positions. Despite the routing scores cited by the school, which favored the railroad, the board agreed with Eversource that itโs not practical to score routes that have a โfatal flawโ or other serious disadvantages that make them almost impossible to build, which was Eversourceโs claim. The board also found that the schoolโs proposal was at a much earlier engineering stage than Eversourceโs Vassar Street route, making assertions about cost, constructibility and reliability uncertain.
The tentative decision also cited Cambridgeโs preferences as communicated to Eversource, including avoiding the Grand Junction railroad. The board noted that the city had โexpressed strong reservations to the [MIT route] and had clearly stated it may not be willing to issue necessary permits.โ In a footnote, the board suggested that Cambridge had no veto power. While โCambridge has played an active, important and constructive role in the evolution of the proposed projectโ and the siting board gave โconsiderable weightโ to the cityโs recommendations, โthe board also exercises independent judgment in reviewing such recommendations in conjunction with other evidence and arguments in the proceeding,โ the footnote said.
Overall, the board found that MIT hadnโt shown its proposal was โclearly superiorโ to the Vassar Street route. โAccordingly, the siting board does not advance the [MIT proposal] further for detailed evaluation,โ the tentative ruling said.
Conditions for Eversource
The decision included several conditions imposed on Eversource, including:
Because the water table at the underground substation is much higher than the 11-story depth of the facility, there is a โpossible risk of water infiltration of the vaultโ enclosing the substation. Eversource must develop a โmaintenance protocolโ to evaluate the performance of โsealant jointsโ and report any โincidents and any remediation measures.โ
The company must review projections of โsea level riseโ by Cambridge and the state every five years and file a report with the siting board โanalyzing the necessity, appropriateness and cost of implementing additional flood mitigation measuresโ at the underground substation.
Eversource must generally limit construction hours to 7 a.m. to 7 p.m. on weekdays and 9 a.m. to 6 p.m. on Saturdays, with some exceptions. The company must get written permission from communities to extend the hours, except for emergencies.
The utility must develop plans to notify the public about construction and traffic measures. The plans must include a way for residents to contact the company.
Eversource is required to get approval from the Cambridge Fire Department and โother jurisdictional authoritiesโ for a fire safety design and plan for the underground substation and work with the department to create an emergency response plan. The emergency plan must be submitted to the siting board before construction starts.
Eversource is ordered to use โmultiple crews, where practicable,โ to meet MITโs concerns about construction and also to communicate โcloselyโ with MIT about construction activities. The board rejected MITโs request that the agency order Eversource to sign a memorandum of understanding about specific mitigation, but did say the two parties should continue negotiations and report back on the status 60 days after the final siting board decision.
Somerville did not persuade the board to order Eversource to build space to put overhead wires underground in the cityโs portion of the project, in Union Square and Boynton Yards. The board said that the cost of burying all the wires, including ones that do not provide electricity, is unknown and the request is outside the scope of its authority.



Good! Now letโs going as soon as possible! Letโs show we can build some needed electrical infrastructure in this city!
Necessary work if the city hopes to move towards a greater electrification of homes and businesses as they have been pushing for. Without this being in a functional state pushing the electrification agenda will over tax our power grid distribution capacity and have safety concerns.
I’ll be really surprised if this gets built. I’m not sure how the conditions could ever be satisfied and the construction limitations for something that is apparently critical doesn’t seem to match the moment. That it’s a “first of its kind” project along with the flood mitigation and review likely means that the $2B price tag which was $1.4B like a year ago is likely to be even higher.