Concord Gasholder Engineering Investigations Under Way
Team assessing underground structures to prepare for next phase of work
Gasholder project team members prepare to enter the Concord, NH Gasholder for subterranean engineering investigations in December 2025
In December 2025, the Concord Gasholder project team investigated the underground portions of the Gasholder to finalize next-phase preparatory work, including engineering plans. The goals are to assess and document the structures under the metal tank to verify that they are sufficient to support additional weight during future roof restoration work. Though the entire investigation was conducted underground, there was plenty of activity on site, and robust public interest and news coverage.
Engineers and crew from Structures North Consulting Engineers and Yankee Steeplejack Company conducted the work, with Milestone Construction serving as the general contractor. The Concord Fire Department rescue squad and vehicles were on standby to keep everyone safe in case of emergency, and to comply with federal OSHA regulations for confined spaces. The investigation was carried out without incident.
The Gasholder’s slate roof has been stabilized since 2022 with a carefully engineered system of steel shoring towers inside the brick house. The long-term goal over the next couple of years is to straighten and repair the roof and remove the shoring towers, so the building stands on its own again, and the interior space is wide open and unobstructed as it was originally.
The team hopes to have an engineering report in early 2026 after the engineers have analyzed the data and finalized next steps, and to begin the next phase of restoration on this last-of-its-kind landmark in 2026.
The campaign to save and repurpose the 1888 Concord, NH Gasholder has made tremendous progress toward protecting this last-of-its-kind landmark for public benefit. Property owner Liberty, the City of Concord, and the New Hampshire Preservation Alliance have collaborated to put the Gasholder project on the road to success, with broad support from the community. With the structure stabilized, the project partners are moving forward with a new phase of complex restoration work. The project has been thoroughly documented, including in this video celebrating the history and relevance of the Concord Gasholder.
The Gasholder, listed on the National Register of Historic Places, is considered the last of its kind in the country. Cities around the globe have turned their gasworks sites into vibrant community destinations, revitalizing neighborhoods and supporting economic development. Decommissioned in 1952, the Concord Gasholder has received national and international attention from as far away as Sweden.
In early 2024, the New Hampshire Public Utilities Commission (PUC) determined that a preserved and weather-tight Gasholder can be expected to serve as a highly effective cap at a lower cost than demolition, making it the best and least-cost option for Liberty’s customers. The PUC authorized Liberty to commit as much as $2.4 million to stabilize, preserve and utilize the Gasholder as part of its ongoing efforts to protect the environment, public health, and safety while minimizing the financial impact on its customers.
The N.H. Preservation Alliance helps strengthen communities and local economies by supporting and encouraging the revitalization and protection of historic buildings and places through leadership, education, and advocacy. The Preservation Alliance invites comments and questions about the history and future of the Gasholder and the Save Our Gasholder campaign. Learn more on the FAQ page.
The Concord Gasholder team invites your comments and suggestions. Contact the New Hampshire Preservation Alliance at (603) 224-2281 or email projects@nhpreservation.org.