New regulations in Massachusetts, which received input from several local distribution companies (LDC), would require the utilities to repair some of the most severe underground pipeline leaks within two or three years.

The regulations, specifically Section 220 of the Code of Massachusetts Regulations, Uniform Natural Gas Leaks Classification, were proposed by the Commonwealth's Department of Public Utilities (DPU) and took effect March 22.

The state of aging gas lines in Massachusetts took on new urgency following a series of deadly natural gas explosions last September in the Merrimack Valley. Republican Gov. Charlie Baker's administration filed legislation in November requiring that all natural gas work that could pose a risk to public safety be reviewed and approved by a certified professional engineer.

Under the rules, pipeline natural gas leaks are ranked using a three-grade system, with Grade 3 the most severe. Such leaks are defined as being "nonhazardous to persons or property at the time of detection and can be reasonably expected to remain nonhazardous." Grade 3 leaks are classified as having a significant environmental impact (G3SEI) if the highest barhole reading from the leak shows a gas-in-air reading of 50% or higher, or if the extent of the leak is 2,000 square feet or more.

The timetable for LDCs to make the necessary repairs to G3SEI leaks depends on whether the leak is on infrastructure included in a gas system enhancement program (GSEP). LDCs have three years to repair leaks found on GSEP-eligible infrastructure with a barhole reading of 50% or higher, or that have a leak extent of 2,000-10,000 square feet, provided the GSEP system itself is scheduled for repair within five years. Leaks with an extent of more than 10,000 square feet would need to be fixed within two years, assuming the GSEP system itself is scheduled for repair within three years.

On infrastructure that is not within a GSEP, LDCs are required to repair within two years G3SEI leaks with a barhole reading of 50% or higher, or that have a leak extent of 2,000-10,000 square feet. Leaks with an extent of more than 10,000 square feet need to be fixed within 12 months.

LDCs are also required to report gas leak information quarterly to the DPU. During the rulemaking process, the regulatory agency received input from several LDCs, including subsidiaries of Columbia Gas, Eversource Energy, Liberty Utilities Co. and National Grid.

The new regulations follow a 2018 report by the nonprofit climate change group Home Energy Efficiency Team Inc. (HEET). According to HEET's Large Volume Leak Study, 33% of the 83 leaks identified for the report were from cast iron pipe, while 32% were bare steel. Columbia Gas, Eversource and National Grid participated in the HEET study and agreed to a shared action plan with the group.

The plan calls for, among other things, having LDCs use leak extent as the sole proxy method for identifying large volume leaks, at least for the first year of testing.