Replacing Concord Steam with new pipes continues to snarl downtown traffic

  • This map shows steam lines being installed under streets and sidewalks in downtown Concord to provide heat to the State House, State House Annex, and the New Hampshire State Library. Other buildings, such as the Department of Justice and the Legislative Office Building, are being heated by their own gas boilers. The steam will be generated in the building marked in gray in the lower left.   Courtesy—NH Dept. Admin. Services

  • Steam pipes are shown on Green Street in front of the State House on Tuesday. The work on the downtown project has continued to slow traffic. GEOFF FORESTER photos / Monitor staff

  • Park Street and the adjoining sidewalk is all torn up as crews work on the steam project on Tuesday.

  • The work along Green Street in downtown Concord for the steam project on Wednesday, April 3, 2019. GEOFF FORESTER—Monitor staff

  • The site work for the steam project along Green Street in downtown Concord on Wednesday, April 3, 2019. GEOFF FORESTER—Monitor staff

  • Part of Green Street in Concord is shut down to traffic because of steam pipe work on the east side. GEOFF FORESTER / Monitor staff

Monitor staff
Published: 4/3/2019 12:25:03 PM

Replacing the defunct Concord Steam heating system will continue to complicate driving in downtown Concord for the rest of the year, including changes made this week to traffic in front of City Hall.

“There are things in the road that we keep finding and under the sidewalk – old pipes that we don’t know where they go – that are complicating it,” said Michael Connor, deputy commissioner of the state Department of Administrative Services, which is overseeing the project.

Starting this week, Green Street between Park Street and Capitol Street, in front of City Hall and the Concord City Library, will be reduced to a single southbound lane. Northbound traffic on that block will be detoured.

Crews are trenching in the streets and under sidewalks all around the State House to install pipes that will carry steam heat from a new building on the corner of School and Green streets. That building, which holds a pair of 250-horsepower boilers fired by natural gas, is nearing completion.

Connor said work installing the new pipes will probably last through December, although it was originally supposed to be done by October.

Most of the steam pipes are four inches in diameter, surrounded by a foot or more of insulation, with two-inch condensate pipes carrying the liquid of condensed steam back to the boiler house. Connor said the pipes are buried about three feet deep on average, although that can vary depending on what else is underneath the road, and because the pipes must be placed at a slight angle to help the flow of liquid.

“The intersection of Green and School (streets) where the boiler supply is, there is just a myriad of utilities there. Walk out and look at all the manholes; every one is a utility,” Connor said. Pipes might have to be placed as deep as 8 feet understand at that point.

A half-dozen state buildings are still being heated with steam pumped through the old, inefficient underground pipes installed by Concord Steam, the company that provided heat to large parts of Concord for eight decades before competition from natural gas drove it out of business in 2017. They are being heated from a 500-horsepower boiler in a temporary facility on the parking lot of the Department of Justice building.

Most of the scores of buildings served by Concord Steam, including several by the city government and three state buildings – the Legislative Office Building, Department of Justice and the Upham-Walker Building – are now being heated individually, usually by forced hot water systems from individual boilers installed in each structure.

The new steam pipes being installed will heat the State House, State House Annex, and the New Hampshire State Library. Those buildings were judged to be too historic to be torn up to allow a new heating system to be installed.

When the new steam system is up and running, the old Concord Steam pipes will be closed off and abandoned, probably filled with concrete so they don’t collapse in the future, and the boiler house will be removed from the Department of Justice parking lot.

The buildings in the Gov. Hugh Gallen State Office Park that were heated by the Concord Steam plant located in the facility are now heated via natural gas.

(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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