Cheap, Fast, and Easy Emissions Reduction

Fixing the largest 7% of the Grade 3 leaks in our streets reduces methane emissions by 50%. That is a cheap, fast, and easy way to reduce emissions of a very harmful and dangerous gas. 

Thanks to the 2017 Shared Action Plan, utilities are now responsible for repairing these ‘super emitting’ Grade 3 leaks they have identified. HEET is responsible for verifying the data and repairs. This year, HEET staff spent extensive time in the field, finding and testing a random sample of leaks drawn both from the utility leak lists and by identifying undocumented leaks. 

Utilities share leak addresses, reports, and repair dates of all super emitting  leaks with HEET, then HEET randomly surveys 100 leaks to ensure the accuracy and consistency across utilities. In practice, many more are surveyed by HEET to establish a robust data set of the method. 

HEET staff sample a statistically significant portion of streets in Massachusetts using two methods. One approach is to measure the leak extent of Grade 3 leaks the utilities have listed to assess whether the emissions volume is accurate. The second method is to drive through areas with gas pipes to test whether all Grade 3 leaks have been found, using highly sensitive equipment.

Data from 100 Grade 3 large volume leaks showed that about a third were smaller, a third were unchanged or larger, and a third were fixed. In some cases the largest leaks were reclassified as Grade 1 leaks.

Collecting these data is part of the promise of the Shared Action Plan: to share data, verify it, and reassess methodologies. HEET and the utilities are partnering to cut a significant portion of emissions in just a few years. 

How do you grade a leak?

Gas leaks are graded by degree of hazard—Grade 1, the highly explosive ones, must be fixed immediately; Grade 2, which are likely to become explosive, must be fixed within 15 months; and Grade 3. Grade 3 leaks occur beneath pavement or another open space. In the past they were considered non hazardous because the gas dissipates into the open air. That gas, of course, is methane.

Grade 3 leaks may be non hazardous in the sense that they are less likely to explode compared to the first two categories, but they are highly dangerous from a climate perspective. Methane is 84 times more damaging to the atmosphere than carbon dioxide over a twenty year period. Given that we have about ten years to dramatically cut the amount of greenhouse gases entering our atmosphere, the flow of methane from Grade 3 leaks must be taken seriously.

HEET is responsible for requiring that the state recognize Grade 3 leaks and for identifying the fact that 7% of these leaks are responsible for 50% of the volume of emissions. Since 2016 utilities have been required to measure Grade 3 leak emissions and repair the large volume leaks that have Significant Environmental Impact (SEI), and most utilities comply. 
This work is supported in part by a PHMSA (Pipeline and Hazardous Materials Safety Administration) grant.