Gas Infrastructure Audit

Like many towns in Massachusetts, Weston has a gas leak problem due to the state’s aging gas infrastructure, which is the second oldest in the country. At the end of 2017, National Grid, Weston’s gas service provider, reported 141 unrepaired gas leaks in town, some of which were over 20 years old. 

Not only are gas leaks a safety concern, but they are also an environmental and health issue for our community. Methane is 86-times more potent as a greenhouse gas than carbon dioxide over the first 20 years in the atmosphere, contributing significantly to the climate crisis. 

With the support of the Town's newly established Sustainability Committee, the local citizens' group, Sustainable Weston Action Group (SWAG), approached the Select Board with a request for the Town to conduct an independent audit of its gas infrastructure in order to better understand its full condition.

Audit Results

The results of the Final Audit confirm the gas leak problem in Weston is worse than reported:

  • December 2017: National Grid reported 141 Grade 3 unrepaired gas leaks
  • December 2018 National Grid reported 175 Grade 3 unrepaired gas leaks
  • June 2019 Weston Gas Infrastructure Audit confirmed 295 unrepaired gas leaks:
    • 102 leaks were measured at 2,000 sq. ft. or more* 
    • 166 leaks were misclassified: 2 leaks were identified as Grade 1 leaks for immediate repair; 164 leaks were identified as Grade 2 leaks, as the gas leak had already or was at risk of causing damage to property, including trees, shrubs, and lawns
    • A total of 325 trees were identified as either already compromised or at risk, due to their location in the gas leak zone

SWAG prepared a one-page summary of the Gas Audit Analysis (PDF) for download.

* Under new Department of Public Utilities (DPU) ruling, these are classified as “Significant Environmental Impact” leaks (SEI). In Massachusetts, the average percentage of known leaks classified as SEI for a community is 5-7%. In Weston, 35% of the leaks are SEI classified. Two of those are exceptionally large at over 10,000 sq. ft.

Interactive Audit Report

Below is an interactive map showing the location of all unrepaired gas leaks in Weston confirmed in the audit that was conducted in 2019. Click on a leak location pin to get more information about that leak including the exact location, date reported, leak size, trees impacted, and a link to a detailed sketch of the leak extent.

Regular leaks = leaks that measure <2,000 square feet

Large volume leaks (SEIs) = Significant Environmental Impact leaks according to the Mass. Department of Public Utilities regulation, measuring 2,000 square feet or more

The map was created by HEET - Home Energy Efficiency Team - a non-profit organization in Massachusetts working to improve energy efficiency in homes and communities across the state. See more at