Located at 54 Wilson Street and situated between Legacy Farms and Cedar Street sits the largest Liquified Natural Gas (LNG) Peak Shaving plant in New England. Built between 1967 – 1975 by the Worcester Gas and Light Company, the facility is owned by the Hopkinton LNG Corporation which contracts with the NSTAR Gas Company, a subsidiary of Eversource Energy. The facility receives gas for liquefaction from two interstate natural gas pipelines – Algonquin Gas Transmission and Tennessee Gas Pipeline, a subsidiary of Kinder Morgan.

The purpose of the facility is to store LNG during the summer (when demand is low) for delivery in the winter (when demand is high). This keeps the pricing stable throughout the year. According to Eversource, the facility now serves more than 300,000 customers in 36 towns.

The facility houses three cryogenic storage tanks which store the LNG at -259º Fahrenheit. Each tank has the capacity to hold one billion cubic feet of vapor equivalent of liquified natural gas, or 7,480,519,480 gallons in each tank. There are two pipelines that cross under the Wilson Street roadway and lead to the liquefaction and vaporizer facility. 

Risk of Fire and Vapor

There are many risks associated with a LNG plant being located near where people live and work. The most obvious is the risk of fire; LNG (in vapor form) is highly flammable and can be explosive if confined. Its flame propagates rapidly and it has a burn rate about twice as high as gasoline and a much higher flame temperature. It is easy for a large area of fire to form and it is difficult to stamp out. Adding water to a LNG fire just intensifies it. That is why foam (unfortunately containing PFAS) was added to the Hopkinton Fire Department’s capabilities in the 1970s.

Any fire in one tank would almost certainly lead to a rupture and fire in the other tanks. Because of the high temperature of a LNG fire the tanks would melt, causing massive spillage, flooding the dike and creating an uncontrollable fire that would spread to the forest and nearby residences. 

A rupture of all three tanks (however unlikely) would release the energy equivalent of about 501 kilotons of TNT (how we calculated this). By comparison, the atomic bomb dropped on Hiroshima in 1945 released 15 kilotons of TNT. 

What is less obvious is the risk of a vapor leak. Surrounding the area is a single protective dyke, the purpose of which is to catch any spillage from a cracked tank or broken pipe. (In 2015 federal regulations changed, requiring a dyke for each tank, but because the plant was built in 1971 it is grandfathered in.)

In the event of a crack, once the LNG spills out of the tank and reaches ground, the ground acts as a huge heater, creating a vapor cloud. Unlike normal methane gas, which is lighter than air, this gas is heavier than air because it’s so cold. And though it will be heated by the ground, it won’t be heated to ambient temperature, so there will be a cold layer of gas the floats out. The direction it goes depends on topography and the direction the wind is blowing that day, but because the tanks are at a higher elevation than the homes in Legacy Farms, it almost certainly would flow downhill.

Exclusion Zones and Legacy Farms North

In 2016 members of the Hopkinton Planning Board expressed their uneasiness with the proximity of the LNG plant to the planned residences at Legacy Farms North. In response, Legacy Farms LLC contracted with ioMosaic, a risk management company, to perform an assessment. ioMosaic produced the map below, showing both a Thermal Exclusion Zone and Vapor Exclusion Zone for the LNG plant. The Thermal Exclusion Zone is the edge at which houses and trees will combust from a fire at the LNG plant. The Vapor Exclusion Zone is the probable distance any vapor could travel in the event of a leak. The Vapor Exclusion Zone sits beyond the Thermal Exclusion Zone.

In a letter to the Planning Board dated June 6, 2016, Georges Melhem, CEO of ioMosaic wrote that Legacy Farms LLC would be “installing continuous, decorative, open-flame gas lighting as shown in the attached plan. The continuous, decorative, open-flame gas lighting poles will ensure ignition of any LNG vapor cloud that reaches the LNG facility boundaries…as a result, a vapor cloud fire will not be able to reach beyond the LNG facility boundaries.”

In an email to the Planning Board on April 15, 2016, Legacy Farms developer Roy MacDowell was asked if “alarms or scheduled maintenance (of the lamps) were needed”. MacDowell replied “None is needed. Confirmation that the gas lights are on 24/7 is all that is needed.”

MacDowell continued: “If the tanks fail, the probability of immediate ignition of the developing vapor cloud will be essentially 100% because of the nature of the facility. Even if that is not the case, the proposed open flame decorative gas lighting will cause ignition and the vapor cloud will burn back to the source and cause a pool fire in the dyke.”

In 2016 the Hopkinton Planning Board reluctantly issued building permits for Legacy Farms North, and as part of the permit they required the network of gas lanterns along the perimeter of the Vapor Exclusion Zone as recommended by ioMosaic and promised by MacDowell. The gas lamps were required to be operational prior to the issuance of an occupancy permit, and it stipulated that the “Legacy Farms Landowner’s Association would maintain and operate the gas lamps in perpetuity”.

Gas Lamp Failure

This network of gas lamps is no longer operational. It is unknown how long this has been the case. More than one is badly damaged with missing glass and broken bulbs. Several are shrouded in trees and brush, creating an obvious fire hazard were they to be returned to operation.

Because the lamps are not operational, a vapor leak from the LNG plant will not be intercepted and ignited at the perimeter. Rather it will likely be ignited by someone’s vehicle, home or mobile phone; LNG is combustible with even small sources of ignition.

>> CLICK HERE for the folder of high-resolution images

When questioned about the operation of the gas lamps, Municipal Inspections Director Chuck Kadlik confirmed that he personally inspected them and that they were functioning at the time the occupancy permit was granted.

The Legacy Farms Landowner’s Association (or Legacy Farms HOA) is outsourced to The Dartmouth Group in Bedford. Although the building permit stipulates that the HOA is responsible for maintenance at all times, it is unclear how that works from a practical standpoint. It is very likely that the gas is shut off to the network of lanterns and it is obvious that there is no routine inspection of this critical safety system. 

It is worth noting that while this article focuses primarily on Legacy Farms, some residents of Wilson Street, Kruger Road and Reservoir Road are also at risk as they are inside the Vapor Exclusion Zone.

Pipeline and Plant Safety Record

According to the US Department of Transportation Pipeline and Hazardous Materials Safety Administration (PHMSA), the Tennessee Gas Pipeline had at least 257 significant failures (leaks, fires, and explosions) from 1986 to 2017. Notably, two occurred in Hopkinton.

• On September 24, 2004, a leak occurred in 24″ diameter pipe at a “high consequence area” just upstream of a compressor station, in a pipe manufactured in 1977. 28 people were evacuated as a precaution. The leak was apparently due to the pipe resting on a rock ledge which damaged the pipe, causing a pinhole perforation.
• On February 10, 2015, cold weather caused “natural force damage” to a Tennessee Gas Pipeline when freezing rain or snow entered a vent then froze.

And while the pipeline is one area of concern, it is not the most critical. 

According to recent testimony before the Appellate Tax Board filed by Eversource against the Hopkinton Board of Assessors (more on Eversource’s attempts to avoid paying town taxes later), in 2012 the Energy Supply Department of Eversource voiced concerns about the future reliability of the Hopkinton LNG facility based on its age. Eversource then commissioned Fuss & O’Neill to perform a study to determine whether investments might be warranted to maintain the facility’s reliability in the future.

The Fuss & O’Neill report opined that much of the infrastructure for the Hopkinton LNG facility was designed for a life expectancy of about 40 years, and that the tanks were approaching the end of their expected life. It recommended about $62,000,000 in upgrades to enable the facility to continue to operate.

But the $62 million price tag did not include any money for upgrades, replacements, or improvements to the three cryogenic tanks, and as of June 2021, Eversource had no plans to replace the facility’s three tanks, even though they were close to 50 years old at the time, thus surpassing their 40-year life expectancy. At the time of this testimony one of the three tanks was was temporarily out of commission while being repaired for a thermal anomaly.

Conclusion

Under oath, Thomas Quine, an engineer with extensive experience in the LNG industry, stated that “it would be unlikely that (the Hopkinton LNG) facility would be built today because the tanks were not in keeping with more modern federal regulations that went into effect after 2015.” 

Two of the tanks are now 52 years old and one is 49, well past their expected life. All mechanical things break eventually; it is only a matter of time. 

But most egregious is that residents of Legacy Farms and the surrounding area are unnecessarily imperiled by a non-functioning mitigation system. It is akin to having a network of fire hydrants not connected to a water source. Residents would be well served to demand that the town enforce the terms of the building & occupancy permits.

* this article was corrected on April 28; there are in fact 14 lamps installed, not 12 as the article originally stated. Two of the lamps are not in the location called for in the plan, likely because the installers wished to avoid topographical barriers.