Announcing The Agreement…

HEET, Mothers Out Front and Columbia Gas, Eversource, and National Grid participated in the Large Volume Leak study and agreed, given the results, on the following shared actions as the current best method to deal with large volume leaks in Massachusetts.



  • Grade-3 Large Volume Leaks (Grade 3-LVL) determined using leak extent as sole proxy method, at least for the first year.
  • Leak footprint evaluated with a consistent and defined method across utilities (i.e. either with CGIs/FIs, barhole or drillholes). Method to be decided by utilities.
  • Leaks over 10 years old not prioritized for repair unless it is an LVL.


  • Leaks > 10,000 sq. ft. fixed within 12 months of determination by leak repair or main replacement.
  • When 2,000 to 10,000 square foot leaks are discovered and verified, LDCs will endeavor to repair them within two years with the exception of inaccessible or challenging leaks which shall be repaired when access can be gained. If any 2,000 to 10,000 square feet leaks are on pipe that will be replaced through GSEP within five years, we will endeavor to eliminate the leak within three years.
  • An LDC may choose to cap its environmentally significant leak repairs in any one calendar year at 7% of its total Grade 3 leak inventory as indicated in the previous year’s final quarterly leak report on file with the Department of Public Utilities


  • For first year, at minimum, a statistically significant randomized sample of Grade 3-LVL leak repairs are FluxBarred prior to repair. Method of verification to be reassessed annually, see below.


  • On GSEP reports, the number of known LVL leaks on each pipe segment.
  • On Annual Service Quality reports the leak address, leak footprint, date leak was reported, LVL classification date and repair date.


  • Methods and results reassessed and adjusted annually for at least five years by a panel made up of utilities, HEET research team, and a mutually agreed-upon independent third party to provide recommendations to DPU.



An initial year collaboration to support the transition. Leak addresses, reports and repair dates of all high emitters shared with HEET to allow for random survey of 100 leaks, in order to ensure consistent implementation across utilities. FluxBar data forms shared with HEET for the first year to provide additional analysis.