Concord gasholder building is elegant, unique and expensive to fix

Last modified: 10/9/2015 1:00:43 AM
As unusual and disheveled as the historic Concord gasholder building looks on the outside, where the crooked cupola and three-story scaffolding clash with the building’s round shape and elegant brick windows, it’s even more so on the inside.

The interior of the huge building, 88 feet in diameter and more than 30 feet high in the center, is a single circular room, once filled with a floating metal tank that held gas manufactured by burning coal, a major fuel for lighting and heating before natural gas arrived in town in 1952.

The building, constructed in 1888, is lit only by daylight from 14 tall, thin windows. Its slate-tiled roof is held up by what looks from underneath like an enormous wagon wheel of supporting lumber, including 16 huge beams, each at least 40 feet long, radiating out from a compression ring in the center.

“The roof was constructed like a work of art,” said Mary Casey, environmental manager for Liberty Utilities, during a tour of the building on Tuesday.

“It’s a very elegant solution,” said James Weick, project manager for GZA GeoEnvironmental of Bedford, the contractor hired by owner Liberty Utilities to oversee the site. “But it makes things complicated when you have to go do some repairs.”

There are plenty of repairs, because like many old works of art, the Concord gasholder hasn’t aged well.

Slate tiles sometimes fall off the roof – hard hats are required if you visit – and pigeons get in through broken cupola windows. The circular design seems to have caused the building to twist slightly over the decades, said John Murphy, senior principal with GZA GeoEnvironmental, which is why the cupola is crooked.

Worst of all is the hole punched in the roof by a falling tree limb in 2013. Repairing it required the construction of eye-popping scaffolding atop steel I-beams that had to be hauled in because most of the floor isn’t weight-bearing. Scaffolding also remains on the outside of the building’s north face, crammed up against the property line.

Things aren’t any better lower down, with crumbling concrete, cracked bricks and general damage visible everywhere on walls, lintels, doors and windows, inside and out. The Concord Fire Department has marked the building with a big red “X,” signifying that it’s not safe for firefighters to enter if the building catches on fire.

Liberty Utilities has already spent a “couple hundred thousand” dollars to keep the building from deteriorating further, most of it on the roof repairs, Casey said. The company isn’t enthusiastic about spending a lot more on the building or the rest of the 2.4-acre property on South Main Street, which it inherited after buying National Grid’s natural gas business in New Hampshire in 2012, because it serves no useful purpose.

Liberty Utilities is in the process of cleaning up the rest of the property, which once held a dozen buildings and underground tanks or pipes used to make gas, first by burning coal and then a process called carbureted water. Both processes left plenty of nasty residue, especially thick, viscous coal tar.

“It’s similar to an asphalt. It sits in the ground and can stay there forever. It doesn’t break down very much, and it does have some toxicity – but because it’s not mobile, it’s not usually a risk,” said Peter King, an environmental engineer with Geosyntec Consultants of Acton, Mass., who is not associated with the Concord site. Other pollutants associated with manufactured gas include poly-aromatic hydrocarbons, which can cause cancer, and chemicals including cyanide. Digging into polluted ground at manufactured gas plants often releases the smell of mothballs due to a chemical called napthalene.

Many polluted sites of former manufactured gas plants exist throughout New England, including at least 16 in New Hampshire, all in various states of clean-up.

King said that Liberty Utilities has a good reputation among gas utilities for the way it handles such sites.

“Sometimes utilities literally sit on the property, maybe maintain an office building over the coal tar, pave it over, sort of kick the can down the road. Liberty Utilities has decided to get them off the books, has done a lot of remediation,” he said.

Cleanup efforts in Concord before Liberty arrived included the removal of 700,000 gallons of water and residue from the basement of the gasholder building in 1994 and removal of 23,650 gallons of sludge from tanks and other “subsurface structures” in 2010 and 2011.

As a result, Casey said, “This is quite far along.”

Several monitoring wells exist on the site and some neighboring properties, and within the next year Liberty Utilities plans to bring in equipment for a final search for any underground tanks or materials. If no surprises show up and the state Department of Environmental Services gives its okay, the site could be ready for limited commercial or industrial redevelopment in a year or two. It could not be used for residential development, Casey said.

All of this, however, leaves the question of the gasholder building.

State and local historical groups would like to see it fixed up because it appears to be the only intact building of its type left anywhere in the country. Other gasholder buildings exist – the post office at St. Paul’s School is in one of them – but those stored purified gas at the end of a pipeline ready to be shipped to customers. The Concord gasholder held unpurified gas during the manufacturing process, a much 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.

If the building is torn down, the basement would be capped, probably with concrete and then dirt and grass, to remove the chance of contact with any underground pollutants.

Casey said it’s possible that the building could be preserved, the basement filled in with concrete as a cap and the upper portion put in usable state. How much that would cost, and who would pay for it, remains to be seen.

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


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