Report: Saving Concord’s gasholder will cost at least $1.4 million

  • The iconic gasholder building on South Main Street in Concord is seen on Monday, Jan. 29, 2018. The structure has been added to the National Register of Historic Places. (ELIZABETH FRANTZ / Monitor staff) ELIZABETH FRANTZ

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

  • The iconic gasholder building on South Main Street in Concord is seen on Monday, Jan. 29, 2018. The structure has been added to the National Register of Historic Places. (ELIZABETH FRANTZ / Monitor staff) ELIZABETH FRANTZ

Monitor staff
Published: 7/16/2020 11:31:56 AM

It would cost at least $1.4 million to preserve the historic gasholder building in Concord even if no public access is allowed, according to a new engineering analysis, and turning it into a usable building involves so many variables that it’s unclear what the final bill would be.

The report says that even tearing down the 132-year-old brick structure would cost at least half a million dollars, with the exact cost depending on how much clean-up of the property would be required.

That’s the conclusion of a report released Wednesday by the firm GZA Geoenvironmental, which was hired by Liberty Utilities, owner of the 2.4-acre property. The future of the historic building is likely to be considered later by the City Council, which has expressed interest in preserving it but balked at potential costs.

The circular brick structure on S. Main Street near Exit 13 was built in 1888 to store and release gasses made from coal, which was used for lighting and heat downtown before natural gas arrived in Concord in 1952. The building, 88 feet in diameter and almost 30 feet high in the center, is a single circular room that holds a floating metal tank that contained up to 120,000 cubic feet of coal gas.

Other unused gas holder buildings exist in the country, including a smaller one at St. Paul’s School, but Concord’s building may be unique because it contains the internal tank and other mechanisms dating from its working days. Such material has usually been removed or encased in concrete as part of turning the building into usable space. This unusual aspect of Concord’s gasholder is part of the reason it was placed on the National Register of Historic Buildings.

Liberty Utilities inherited the building and surrounding property when it bought National Grid’s natural gas business in New Hampshire in 2012. The company says it has no use for the property, which is not part of the natural gas system, and has looked to sell it.

The gasholder building sits over a 24-foot-deep basement that was filled with water and held a floating metal tank that lacked a bottom and is often described as an upside-down cup. As coal gas was created it was pumped into the cup and raising it; as gas was sent out into the city the cup would lower again. The building served as protection from the elements, and an arrow on the outside wall showed the height of the tank and thus how much gas it contained.

The seven decades since the system shut down have not been kind to the gasholder building. A tree fell on it in 2014, knocking a large hole in the slate roof that has been patched, although some holes exist, and the entranceway collapsed in 2016 and had to be removed. The report details many other issues, including the noticeably tilted cupola atop the building, which it says is “due to the movement of certain primary roof rafters” and which may have been caused by storms many decades ago.

“Several areas of significant damage, loose bricks and step cracking in mortar were observed within the entry vestibule on the south side of the structure and the perimeter wall on the north side of the structure proximate to the damaged tension ring at the roof line. Bricks and roof slate that appeared to have fallen from the structure were also noted on the ground surface on the north side of the structure,” the report said.

“Bird guano was observed throughout the (building). Combined with moisture, bird guano can accelerate steel corrosion,” the report noted.

The interior is filled with a scaffolding structure that reaches to the roof. The GSV report says that this structure, built in 2010, is still in good shape but warned that guano-heightened corrosion could weaken it.

The report said that repairing the building so that it would remain standing, which it called the “Monument Option,” could cost from $1.47 million to $1.93 million and take half a year.

Making the building safe for public use would cost far more since it would trigger other requirements in the property as a whole. Details, the report said, would depend on what use is sought: “For example, a storage facility and a restaurant will have very different requirements relative to the redevelopment of the building.”

Removing the building would cost from $500,000 to $700,000, partly because of the need to build a cap to prevent any byproducts being released from the residue of decades of coal processing. Merely figuring out how much contamination exists and how much capping will be needed will cost at least $75,000.

At the very least, the report said, the perimeter fencing and security needs to be improved, which could cost $200,000.

A second gasholder made of metal was built on the site in 1921. It was torn down in the 1980s along with a number of other buildings that helped process the coal gas and pump it throughout downtown.


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

David Brooks is a reporter and the writer of the sci/tech column Granite Geek and blog, as well as moderator of Science Cafe Concord events. After obtaining a bachelor’s degree in mathematics he became a newspaperman, working in Virginia and Tennessee before spending 28 years at the Nashua Telegraph . He joined the Monitor in 2015.

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