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majorprojects

Seacoast Reliability Project

To help ensure that the New Hampshire Seacoast Region can continue to grow and thrive, Eversource completed the construction the Seacoast Reliability Project, a new transmission line connecting two existing substations.

The project includes a new 115-kilovolt (kV) transmission line extending approximately 13 miles between substations in Madbury and Portsmouth, N.H., along with associated substation upgrades. 

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The project was placed into service on May 29, 2020. The new transmission line will help improve the transmission system in the Seacoast area so that our customers will have reliable electric power to meet their current and growing energy needs. It will also ensure that the area's electric grid conforms to national and regional reliability standards.

Eversource invested more than $126 million in this New Hampshire project designed to bolster the regional infrastructure. While the project will result in direct benefits for New Hampshire communities, residents and businesses ― including the enhanced system reliability for customers, creation of local jobs, and property tax payments in host communities ― the cost of the project will be paid by all electric customers in New England.

See the one-page Seacoast Reliability Project information sheet for more details. 

New Hampshire Site Evaluation Committee

For an electric transmission line project, such as the Seacoast Reliability Project, the New Hampshire Site Evaluation Committee (SEC) Application Filing is part of the siting regulatory review process, as defined by the New Hampshire state statutes. On December 10, 2018, the SEC voted unanimously to approve the construction of the project. On January 31, 2019, the SEC issued its written order, reaffirming its oral approval. The committee’s approval followed a series of public information sessions and public hearings in Concord and in the communities that host the new 115-kV transmission line.

Click here for Post-Certificate Filings for the project, including reports for and from the Department of Environmental Services (NHDES).

Project Timeline:

  • Application filing with the SEC: April 12, 2016
  • SEC verbal decision to approve the project with conditions: December 10, 2018
  • SEC written order and conditions of approval: January 31, 2019
  • Start of construction: May 2019
  • Project in-service: May 29, 2020
  • Project restoration completion: Third Quarter 2020

Construction Updates

Eversource is committed to updating and proactively communicating with neighbors, businesses and all community members about project activities and will continue this outreach throughout the remaining restoration process.

The sections below also feature construction updates for each town.

  • Survey of power line corridor, stone walls and roadways:
    • Environmental surveys are performed periodically throughout the corridor.
    • Construction is complete. Final survey will be performed by the end of the third quarter 2020. Environmental surveys will continue to be performed periodically.

  • EMF readings: 
    • Pre-construction EMF readings: Complete
    • Post-construction EMF readings: July - August 2020

  • Tree clearing: Complete

  • Madbury Substation construction: Complete

  • Overhead line construction: Complete

  • Restoration of power line corridor and landscaping: March, 2020 - End of Third Quarter 2020 
  • Survey of power line corridor, stone walls and roadways: 
    • Environmental surveys are performed periodically throughout the corridor.
    • Construction is complete. Final survey will be performed by the end of the third quarter 2020. Environmental surveys will continue to be performed periodically. 

  • EMF readings:
    • Pre-construction EMF readings: Complete
    • Post-construction EMF readings: July - August 2020
  • Eversource cable house relocation (at 295 Durham Point Road)
    • Relocation to temporary location (during construction): Complete
    • Relocation to permanent location (after construction): August - September 2020
  • Tree clearing: Complete
  •  Overhead line construction:
    • Mill Road to Route 108: Complete
    • Longmarsh Road, Timberbrook Lane, Cutts Road, Ffrost Drive, Sandy Brook Drive, Durham Point Road: Complete

  • Restoration of power line corridor and landscaping: March, 2020 - End of Third Quarter 2020
  • Tree clearing: Complete
  • Underground cable installation: Complete
  • Overhead line construction: 
    • Mill Road: Complete
    • Route 4 to UNH campus: Complete
    • Foss Farm Road, Bennett Road: Complete
  • Restoration of power line corridor and landscaping: March, 2020 - End of Third Quarter 2020



  • Install additional cable protection at Newington shoreline and intertidal area: Complete
  • Salt marsh restoration in Durham and Newington: April, 2020 - End of Third Quarter 2020

To learn more, see the Little Bay Information Sheet.

  • Survey of power line corridor, stone walls and roadways:
    • Environmental surveys are performed periodically throughout the corridor.
    • Construction is complete. Final survey will be performed by the end of third quarter 2020. Environmental surveys will continue to be performed periodically.

  • EMF readings:
    • Pre-construction EMF readings: Complete
    • Post-construction EMF readings: July - August 2020

  • Tree clearing: Complete
  • Underground line construction: Complete

  • Overhead line construction: Complete
    • Includes: Little Bay Road, Fox Point Road, the Crossings at Fox Run, Spaulding Turnpike, Woodbury Avenue, Gosling Road

  • Restoration of power line corridor and landscaping: March, 2020 -End of Third Quarter 2020
  • Survey of power line corridor, stone walls and roadways:
    • Environmental surveys will be performed periodically throughout the corridor. 
    • Construction is complete. Final survey will be performed by the end of the third quarter 2020. Environmental surveys will continue to be performed periodically.
  • EMF readings:
    • Pre-construction EMF readings: Complete
    • Post-construction EMF readings: July - August 2020

  • Tree clearing: Complete 
  • Portsmouth Substation construction: Complete

  • Overhead line construction: Complete

  • Restoration of power line corridor and landscaping: March, 2020 - End of Third Quarter 2020

Project Outreach

We are committed to being a good neighbor and keeping you informed about our work. Similar to the siting and construction phases of the project, we will continue working directly with the community to provide information about the restoration and any remaining close-out work activities and to quickly answer any questions or concerns. Some of the ways that we communicate with residents, businesses and others in the community include:

Project Information Letters: Letters mailed to property owners along the right of way (power line corridor), sharing project milestone information.

Public Open Houses: Information sessions, which were held prior to the start of construction.

Field Outreach Representatives: Eversource representatives are on-site prior to, and during, work. They communicate with local residents and businesses in-person about the project, and respond to any questions or concerns. The safety of our employees, our customers, and the public is our top priority during the ongoing coronavirus public health crisis. Our commitment to safety, first and always, is continuous.

At the same time, Eversource must fulfill its foundational mission to deliver safe, reliable services to our customers, in support of the economic health of New England and the basic needs of society.

The mission is more important than ever at this deeply unsettled time. We continue to call on our employees and contractors to perform this essential work in the field that maintains and improves the reliability of our networks and serves the customers' best interests, while also adapting our work practices to incorporate social distancing, heightened hygiene, and other best practices to protect their, and the public's, health and avoid the spread of coronavirus. 

For the remainder of the project work, Eversource will follow social distancing and other health and safety guidelines in our community outreach efforts. This includes utilizing other forms of notifications such as letters and email and/or phone calls, instead of door hangers and in-person visits.

Project Webpage: Route maps, project schedules, regulatory filings, regular town-by-town project updates and contact information.

Municipal Meetings: Project update meetings with city and town officials held regularly throughout various phases of the project.

Contact Us

For any questions or concerns about the Seacoast Reliability Project, please call us at 888-926-5334, email us at NHProjectsInfo@eversource.com, or discuss directly with the Eversource Field Outreach Representative. We will make every effort to promptly respond to your questions or address your concerns.

In the unlikely event that we are unable to address your concerns to your satisfaction, a process has been developed by the New Hampshire Counsel for the Public and Eversource to provide more help with resolving issues. That process can be found here (see pages 212-218).