Fact Sheet: Large Volume Leak (LVL) Study

By: Audrey Schulman


Massachusetts has the second oldest and most leak-prone natural gas infrastructure in the country. Some of the pipes still in use were first put in the ground in the 1860s. Of course, pipes that old will leak.

There are 16,000 utility-reported leaks in the state.

Natural gas is composed overwhelmingly of methane. Methane is a remarkably potent greenhouse gas, over 30 times more destructive than carbon dioxide to the climate over the first 100 years in the atmosphere.


The 2015 Harvard/Boston University McKain study put devices on top of tall buildings around Greater Boston that sniffed for methane and for ethane, a chemical marker found only in natural gas.

The results showed that 2.7% of all gas in the state leaks into the atmosphere.

Because methane is so powerful, the impact of that lost gas is equivalent to 10% of our state’s greenhouse gas emissions inventory, or roughly the emissions of all our stores and businesses.


The 2016 Boston University Hendrick et al. study of 100 gas leaks in Boston found that 7% of gas leaks are gushers, emitting half of all the gas by volume.

Since fixing these large volume leaks would clearly reduce the problems for the least cost and disruption, a 2016 law required that these “environmentally significant” leaks must be fixed.

Unfortunately, as utilities have always been mandated to worry only about safety, not volume, they don’t have a reliable, scalable method to find these high emitters.

An unusual coalition of activists, academics, utilities, innovators, and nonprofits worked together to discover a quick easy reliable indicator of a large volume leak -the size of the leak footprint!

Using the size of the leak footprint, the utilities can now find and fix the worst gas leaks (approximately 1,100 leaks across the state) to cut the emissions from gas leaks in half.

The coalition have created shared recommendations that include:

  • Using leak extent to find the worst leaks
  • Enough data transparency to know the method is working
  • Annual reassessment of the results so if another less expensive, more reliable method comes along, it can be adopted.

None of the organizations in the coalition could have managed this on their own. The solutions discovered through the collaboration are just the beginning of the impact the coalition can have. It is working together to amplify and accelerate our progress to keep our climate livable.


The three utilities (National Grid, Eversource and Columbia Gas) working on the project together represent 95% of all the gas customers in the state.

They identified leaks as possibly high volume across the state, shared information, and actively worked with the research team — sending utility trucks out to collect data with our researchers.

Organizations/people involved in the study

  • NGOs: HEET, Mothers Out Front, Sierra Club of Massacthusetts
  • Government: Metropolitan Area Planning Council
  • Academics: Boston University Prof. Nathan Phillips, Zeyneb Magavi
  • For-profits: Gas Safety Inc., Millibar, MultiSensor Scientific
  • Utilities: Columbia Gas, Eversource, National Grid

Generously funded by Barr Foundation and Putnam Foundation as well as many individual donations.