New Hampshire’s largest natural gas distributor plans to build a $340 million project to boost the capacity of the state’s existing gas infrastructure. Pending approvals by state agencies, Liberty Utilities’ “Granite Bridge” project will convey natural gas from operating infrastructure in New Hampshire’s coastal region through a new buried pipeline to the central part of the state. The 16-inch steel pipeline is to be located completely within the state’s Department of Transportation’s (NHDOT) right-of-way along Route 101, a designated Energy Infrastructure Corridor.

This new gas source will supplement existing gas infrastructure in an area of New Hampshire where its use is nearing capacity, according to Susan Fleck, President of Liberty Utilities’ New Hampshire operations. Fleck suggested that, without the increase in gas supplies, in a few years the company may have to turn down new requests for natural gas service from residents and businesses.

As a subsidiary of Algonquin Power & Utilities Corp., Liberty Utilities owns and operates water, wastewater, natural gas and electric utilities. The company provides rate-regulated natural gas, water and electricity generation, transmission and distribution services to approximately 758,000 customers in the United States via more than 30 electric, gas and water utility systems in 15 states. The company’s New Hampshire office, located in Londonderry, supplies natural gas to 90,000 customers in 31 communities.

Currently under review by the New Hampshire Public Utilities Commission and several other state agencies, the Granite Bridge pipeline will run from an existing “Joint Facilities” pipeline in Stratham for about 27 miles to the “Concord Lateral” facilities in Manchester. Joint Facilities is co-owned by Portland Natural Gas Transmission System (PNGTS) and the Maritimes and Northeast Pipeline (Maritime), while Tennessee Gas Pipelines (TGP) owns the Concord Lateral. Maritime is a 684-mile transmission pipeline system built to transport natural gas from developments offshore Nova Scotia to markets in Atlantic Canada and the northeastern United States.

Fully Contained LNG Storage

Granite Bridge pipeline will be connected to a liquefied natural gas (LNG) storage facility to be built as part of the project. This storage facility will be located on a 140-acre parcel of land in an abandoned quarry near Route 101 in Epping. With an outside diameter of 200 feet and a height of 170 feet, the LNG facility is reportedly designed with a service life of 40 years and the capability to withstand an earthquake of magnitude 6 on the Richter Scale. The huge vessel is a full containment tank, which typically means it consists of a tank within a tank. An inner steel tank stores the gas, an outer tank can contain the gas if the inner tank leaks, and the annular space between tanks contains insulating material to maintain extremely low temperatures. LNG is a clear, colorless, non-toxic liquid that forms when natural gas is cooled to -260 degrees Fahrenheit. The cooling process shrinks the volume of natural gas 600 times, making it easier and safer to store and ship. In this liquid state, LNG will not ignite. 

The storage facility will have the ability to liquefy and store the gas delivered from either the PNGTS or TGP pipelines in the low-cost summer period, and vaporize that same gas to serve Liberty Utilities customers in the winter when other supplies are more expensive. So this new LNG storage facility is expected to yield cost savings that the company says it intends to pass on to customers. 

Local Workers Wanted 

Liberty Utilities’ Granite Bridge project has been endorsed by the Greater Nashua, Manchester and Concord Chambers of Commerce. Together these three chambers of commerce represent nearly 2,500 businesses who employ thousands of workers across the state. According to the utility, if given the green light for the project, they intend to maximize the number of local New Hampshire workers to fill the estimated 330 full time construction jobs available to complete the project. In line with this, Liberty Utilities President Susan Fleck recently signed a Memorandum of Understanding agreement with New Hampshire Building Trades Vice President Dave Pelletier to build the Granite Bridge using local union labor.

Pipeline Expansion Continues

Nearly all of the company’s natural gas distribution system in New Hampshire is connected to the Concord Lateral and, according to the company, the demand by current and future customers may soon overwhelm the supply source. The utility reports that it added many new customers in recent years, for example: 1,200 customers in 2014; 1,817 in 2015; 1,637 in 2016; and 1,621 in 2017. At this growth rate the company’s natural gas demand will exceed the capacity of the Concord Lateral infrastructure in the near future.

Meanwhile, Liberty Utilities is moving ahead with construction of a gas main expansion and new services in Nashua. Mears Group Inc., a Quanta Services Company, is installing approximately 4,500 feet of 8-inch pipe along Concord Street, a main artery of New Hampshire’s second largest city (population about 89,000). Mears Group specializes in pipeline integrity management and corrosion, horizontal directional drilling/direct pipe, gas distribution construction, and sewer camera inspection. An estimated 6,000 1-inch and 2-inch gas services will also be installed.

For the Concord Street project, Mears Group is employing a Hitachi ZAXIS 50U Excavator to dig the pipe trench and a John Deere 310SL Backhoe Loader to backfill the pipe. Concord Street is an old Nashua thoroughfare with an accumulation of layers of asphalt and Portland cement deck totaling about 9 inches. The gas crew is placing 42-inches of backfill over the pipe.

The Concord Street gas main consists of medium density polyethylene pipe (MDPE), which is being used increasingly by utilities for pipe and fittings. While less dense than more commonly used high-density polyethylene (HDPE), MDPE has good shock- and drop-resistance properties, and is less notch sensitive than HDPE. MDPE also has better stress cracking resistance. 

Representing the City for the gas main installation is Mark Saunders, Assistant Construction Engineer, while Liberty Utilities is represented by Anthony Beland, Field Construction Supervisor. William McGovern III is the New England Operations Manager for Mears Group, and Dave Ricardo is Mears’ Gas Foreman.

Utility Work Must Precede Paving

The gas main project has been expedited because the street has been slated for paving this year as part of a $37.5 million Multi-Year Paving Plan of Action. This effort is expected to dramatically improve the overall condition of the city’s 300 miles of streets. During 2017, the city paved and crack-sealed a total of 30 miles of Nashua streets – far more than the previous average of 5 to 6 miles per year.  The Nashua Department of Public Works plans to pave many more during the 2018 paving season including streets with pavement problems such as Concord Street. Newport Construction won the paving contract for 2018 with a bid of $6.7 million.

Approximately 8,000 feet of Concord Street is being paved. Nashua hired engineering consultants Hayner-Swanson, Inc. and Stantec to assist the city with street selection for paving. Selection criteria includes, among other things, identifying roads that are in distress. Furthermore, engineers are coordinating work with Liberty Utilities and Pennichuck Water to ensure that construction associated with their capital utility projects are completed prior to the road being paved. 

Nashua has a rule that once a street is paved, cutting into a newly paved street is prohibited for a period of five years unless there is an emergency.