Collapse of entrance roof at historic gasholder building reflects its problems

  • The inside of the Gasholder building on South Main Street showing the roof and the scaffolding that rises from the base. (GEOFF FORESTER / Monitor staff)

  • An aerial view of the Gasholder building showing the damage to the roof of the entrance way of the structure.Courtesy photo by Matt Woodfin â 603 Aerial Photography

  • An aerial view of the Gasholder building showing the damage to the roof of the entrance way of the structure.Courtesy photo by Matt Woodfin â 603 Aerial Photography

Monitor staff
Thursday, March 17, 2016
If you recently spotted something different about Concord’s gasholder, the iconic round brick building that has been part of the city landscape since 1888, you’re not alone.

“It didn’t take long for people to notice that the roof has fallen. We heard from several of them,” Liberty Utilities spokesman John Shore said.

Fortunately, the roof that fell earlier this month is over a small entryway rather than the entire building, although the main roof has its own issues, as evidenced by a repair job on its north side.

“The main building wasn’t affected. It is still stable,” Shore said.

Liberty Utilities is leaving the rubble for the moment while it discusses the future of the site with the state, although debris blocks the main entrance to the gasholder, so it will have to be cleaned up at some point.

The collapse is a symptom of the issues facing the building, which dates to the time before natural gas was widely available.

In Concord, as in sites across New Hampshire and the country, gasholders were used to store flammable gas made by processing coal that was brought to sites in railroad cars.

The gas was stored in the basement of the gasholder building. It was kept under water covered by a huge floating metal cap, which in Concord’s case is 88 feet in diameter and weighs several tons. The cap rose and fell depending on how much gas had been pumped under it or pumped out to customers.

The building is round to fit the cap, which could rise almost 30 feet to the ceiling, held in place by wheels on vertical rails along the walls.

The gasholder was used through the 1950s, when coal gas was replaced by natural gas. A second gasholder building, made of metal, existed on the site for five decades before it was torn down in the 1990s along with other coal-processing buildings.

Liberty Utilities obtained the gasholder and 2.4-acre property on South Main Street as part of its 2012 purchase of National Grid’s natural gas business in New Hampshire.

Similar buildings exist – the post office at St. Paul’s School is among them – but the gasholder in Concord is alleged to be the only one in which the storage mechanism is still intact.

In general, gasholder buildings that still exist stored purified gas at the end of a pipeline ready to be shipped to customers, but the Concord gasholder held unpurified gas during the manufacturing process, a more complicated and dirty system.

The New Hampshire Preservation Alliance named the gasholder as one of its “Seven to Save,” an annual list of endangered historic properties in the state.

The problem is money. 

“It would be somewhere between $500,000 and a couple of million dollars” to keep the building intact, Shore said, and it would take many millions to clean it up so that people could enter and use it.

Because there are no modern gas facilities on the property, Liberty Utilities has no use for the building or the site. As a regulated utility, it faces certain limitations on how much it can spend on matters that are unrelated to its core business.

“We don’t want to tear this building down, we really don’t. We we want to come 
up with some solution 
. . . perhaps there’s something we can work out with city or preservation groups,” Shore said. “We’d like to work out something that works for our customers, for regulators, and the city of Concord.”

Shore said Liberty Utilities is scheduled to hold a meeting this month with the New Hampshire Department of Environmental Services over its plans, known as a Remedial Design Report. DES has authority because of pollution that accumulated over the decades at the property, like many gasholder sites, from the processing of coal, although there has been cleanup over the years at the Concord site, and sampling indicates it is clean compared with many gasholder locations.

However, it’s not clear how much contamination exists in the soil underneath the gasholder itself, which complicates the future of the building.

Once DES signs off on the company’s plans, Shore said, it will take the matter before the Concord City Council for further discussion.

The report is likely to contain a number of options for the building, ranging from tearing it down, to stabilizing it so it can continue to operate as a cap for any contamination, to making it usable again, which would probably require removing the underground cap.

(David Brooks can be reached at 369-3313,, or on Twitter @GraniteGeek.)

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