HomeNewsLegacy Farms Residents at Risk from Failed Mitigation System

Legacy Farms Residents at Risk from Failed Mitigation System

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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 Hopkinton LNG Corporation

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. 

Hopkinton LNG tanks

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”.

Legacy Farms North
Legacy Farms North

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.

This gas lamp has been overtaken by trees and brush.

>> 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.


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.

20th Century Homes

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  1. I second the thanks. That was an interesting and informative article. I recall seeing a disaster assessment some years ago that showed the blast radius from an explosion at the plant with damage stretching most of the way to downtown. I think this was before Legacy Farms North was built. I imagine that area won’t fair well if there is an explosion.

    Some questions I still have: What is the risk of explosion versus a big, hot fire? I assume since they install gas flame lamps to intentionally ignite a leak, that the resulting fire in the dyke is unlikely to result in a full-blown explosion of the tanks? Or is it picking the lesser of two evils- the shockwave from the tank explosion is less damaging than if the LNG cloud reaches houses and then ignites? How much tax revenue does this plant contribute to the town?

    • Thank you for your comments, R.W.

      The risk of an explosion is small because it would need to occur in a confined space. What is more likely is a rupture in the tank which would lead to spillage and a big, hot fire, as you put it. If the lamps were operational and the vapor cloud hit them, the resulting fire would burn back to the tank and presumably ignite the dike. But the dike can only handle so much before it overflows, which is why federal regulations now require a dike for each tank rather than a dike surrounding all tanks. In any case, there is not a fire department on the planet equipped to extinguish a fire of this magnitude. It will burn until all sources of fuel (LNG, trees, homes) are exhausted.

      The tax revenue question is more complicated and we are working on an article that explores that angle. Suffice it to say, Eversource is not a good neighbor.

      • No they aren’t! I live directly across the street at The Trails. How do we get the town to shut down this plant now as it lifetime has concluded. I’m not thinking about the ‘lesser of two evils!’. Shut it down! And I’m not interested in ‘a matter of time!’

  2. This is what’s wrong with Massachusetts codes & laws it’s also why electric & gas company’s change their name’s often. They don’t use Massachusetts licensed labor to build and maintain their facilities & are exempt from local regulations. Also the town of Hopkinton had ample chance to acquire the property for open space use. It should not be the burden of hopkinton building department to shoulder continuous inspections to verify the lamp system is functioning.

  3. Thank you for this information. I have always wondered about this as developers starting building in this area. I hope that this article is read by locals and remains at the forefront for action at some point in the near future

  4. As a mitigation system, open flame gas lights are not a best practice. I live in the area and when I saw them first appear I did my own research and concluded that the only purpose served by the installation of open flame gas lights at Legacy Farms is a political one which serves both the developer and the planning board.

  5. Thank you for that informative article. I think that the LNG facility needs to bring their property, plant & equipment up to current code especially with all the people now living close by.

  6. Fascinating! I echo everyone’s sentiment – thank you for shining light on this.

    How were the developers able to get an occupancy permit if only 12 of 14 lanterns were installed? Maybe it’s time for a new municipal inspector.

  7. Thanks for bringing this to light.As a home owner in legacy farms I am deeply concerned about safety of our neighborhood.Town shouldn’t have agreed to the building construction and put us all in this risk at first place.I think we all became some scalp goats in big politics.

  8. Excellent reporting, and thank you for shedding light on this topic. If the LNG tank serves 36 towns (~3 billion cubic feet of gas), how will 12-14 lanterns help mitigate a disaster that will soon occur? It’s only a matter of time.

    • While I am happy the people that occupy these residences are part of this town. We keep getting burned (pun intended) by this developer time and time again. We are well past “fool me once”. When will this town collectively learn this lesson?

  9. I biked through Legacy Farms North this past weekend and noticed one of the gas lamps which I previously had never paid attention to. It was now lit and operational. Great job calling attention to this dangerous problem so that it could be remedied HopNews!

  10. I live in Legacy farms and have walked my dog past these lamps for the last 4 years winter and summer and I have never seen them operational. Today I see that the one I walk past regularly is currently under repair

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