Large Volume Leak Study

“You’ve shown us a path forward and I thank you for that.”
– Maura Healy, Massachusetts Attorney General

In 2016, a law was passed in Massachusetts the natural gas leaks that emit the most must be repaired.

Natural gas is over 90% methane, a powerful greenhouse gas.  Fixing these few big leaks would cut the emissions in half for the least cost and disruption.

The Problem

There are over 16,000 gas leaks across the state. There was no fast, inexpensive and reliable method of identifying which of these were large volume.

Using the best available knowledge, the Department of Public Utilities suggested the utilities use the barhole method to identify the large volume leaks.  It was fast and inexpensive, but no one knew if it would work reliably.


The research team set out to test if the barhole method would identify large volume leaks, and if it didn’t to find another method that would.

Columbia Gas, Eversource and National Grid participated in the study.  They selected leaks to be part of the study using the barhole method.

The researchers studied these leaks, first by surveying each of the leaks.

The research team used a Picarro (a high precision GPS-enabled natural gas analyzer) to see if it could identify large volume leaks.

The researchers measured the emissions of each of the leaks using the chamber method.  It is a scientifically verified, peer-reviewed technique for comparing the rate of emissions.

 One of the methods tested was the MultiSensor Scientific camera.  It is a developing technology that will find leaks and compare the leak rates through infrared spectroscopy.

HEET, Mothers Out Front, Millibar, Columbia Gas and Eversource also created the FLUXbar to give the gas companies a fast and reliable apples-to-apples comparison between leaks.

“The results will be of interest to engineers across the gas industry.”
– Neil Proudman, Vice President, New England Gas Operations, National Grid


  • Leak Footprint: leaks with a gas-saturated surface area of over 2,000 square feet were found to emit the most
  • The FLUXbar was found to be the best method of verifying that a large leak was correctly selected.  It can provide feedback to the utilities so they can continue to improve.

Taking Action

The three utilities, HEET, Mothers Out Front and the researchers agreed on a shared action plan.  The plan includes:

  • Any leak over 2,000 square feet being prioritized for repair
  • The FLUXbar providing feedback
  • Data transparency, annual reassessment and independent verification

The result will reduce emissions equivalent to half of Massachusetts’ stores and businesses.  They can help gas companies across the country change how they prioritize gas leaks for repair.

Summary of research methods and findings

“This innovation will allow us to save the most emissions for
the least customer cost.”
– Steve Bryant, President Columbia Gas