Commonwealth Of Massachusetts Energy Facilities Siting Board

Project Summary and Notice of Extended Public Comment Period

Trimount ESS LLC (the “Company”) filed petitions with the Energy Facilities Siting Board (“Siting Board”) seeking: (1) approval to construct, operate, and maintain two underground transmission lines, one at 115 kilovolt (“kV”) and one at 345 kV; and (2) individual and comprehensive zoning exemptions from the City of Everett Zoning Ordinance. These petitions have been filed in connection with the Company’s proposed construction of an approximately 700 megawatt (“MW”)/2,800 megawatt-hour (“MWh”) battery energy storage system (“BESS”) and associated infrastructure, including two underground transmission lines and two new project substations, on approximately 20.75 acres of land at 52 Beacham Street (“Northern Parcel”) and 0 South Farm Road (“Southern Parcel”) in Everett, Massachusetts (together, the “Project Site”). The two transmission lines would connect the BESS with the Eversource Mystic Substation, which is located at 173 Alford Street in Boston. The BESS and associated infrastructure are collectively referred to herein as the “Project.” A Project description and a map of the Project Site are provided below. The Siting Board conducted a public comment hearing in this proceeding on April 8, 2025, and a recording of that hearing is available on the Siting Board’s YouTube page at https://www.youtube.com/watch?v=6n66MXFuML4. When serving the Notice of Adjudication and Public Comment Hearing (“Notice”) in this proceeding, the Company inadvertently excluded the map and visual rendering from the Notice mailed to certain residents and property owners. Additionally, the Notice incorrectly referenced Rover Street, instead of Robin Street, which was and remains accurately reflected in the map below. Because of these administrative errors, the Siting Board is extending the deadline to file written comments and the deadline to file for intervention/limited participant status two weeks from the current deadline of April 25, 2025, to Friday, May 9, 2025.

Important Dates

• New Deadline to file written comments Friday, May 9, 2025
• New Deadline to file for intervention/limited participant status Friday, May 9, 2025

Public Review of the Company’s Petition

A detailed description of the Project, links to the Company’s petitions, attachments, and analysis, and periodic updates are available via the Siting Board’s webpage for the Project https://www.mass.gov/info-details/everett-battery-project. The Company also maintains a webpage for the Project: https://www.trimountenergy.com. The Company’s webpage provides Project information in English, Spanish, Haitian Creole, and Brazilian Portuguese. Hard copies of the Company’s petitions, including all attachments, are available for public inspection at the following locations:

Boston

Energy Facilities Siting Board,

One South Station, 3rd floor, Boston, MA 02110

Boston City Clerk’s Office

1 City Hall Sq Ste 601, Boston, MA 02201

Boston Public Library

179 Main St, Charlestown, MA 02129

Everett

Everett Clerk’s Office

484 Broadway, Room 10, Everett, MA 02149

Parlin Memorial Library

410 Broadway, Everett, MA 02149