By TIM FAULKNER/ecoRI News staff
PROVIDENCE — The March 29 natural-gas leak on Allens Avenue now has two quantified impacts on the environment. The rupture of the high-pressure pipeline owned by Spectra Energy released about 19 million cubic feet of natural gas ($58,000 worth), or enough natural gas to heat and keep the lights on for 190,000 homes for a single day.
About 2 gallons of polychlorinated biphenyls (PCBs) were also released, in the form of contaminated natural-gas condensate, according to the Department of Environmental Management (DEM).
Natural gas is mostly methane, a greenhouse gas between 25 and 33 times more potent than carbon dioxide over 100 years. During the first 20 years, methane is 84 times more potent than carbon dioxide. According to the Environmental Defense Fund, methane accounts for 25 percent of manmade greenhouse-gas emissions. The oil and gas industry is the largest source of industrial methane emissions.
Recent studies suggest that methane leaks during the extraction, transmission and storage of natural gas nullify the supposed benefits of burning the fossil fuel instead of oil or coal.
President Trump, however, has issued executive orders repealing regulations that reduce methane leaks at natural-gas wells. He also has instructed the Environmental Protection Agency to repeal regulations that require natural-gas companies to report methane emissions during fracking.
There are thousands of natural-gas leaks at any time across southern New England. A study released in March by the Sierra Club of Connecticut found 3.2 leaks per mile of road in Hartford. In addition to the climate impacts, the cost of leaked fuel is passed on to ratepayers.
Rhode Island has about 1,000 low-grade leaks that National Grid is repairing. But the rupture on Allens Avenue was classified as a Grade 1 leak requiring immediate repairs to prevent an explosion or fire.
The presence of other contaminants and the public-health impact from the late-March incident haven't been made public. Soon after the accident, DEM acknowledged that PCBs were released. The state agency said it isn't aware of any contamination of state waters, including groundwater. The Department of Heath is expected to issue information about the health effects of the accident.
According to the Public Utilities Commission (PUC), the leak was likely caused by stress on a section of 12-inch, high-pressure pipe at a regulator station owned by National Grid and Spectra Energy of Houston. Two sections of pipe were exposed after soil was removed around and below the pipeline. The lack of support left “3,000 pounds of steel hanging open” and likely caused a coupling to fail, said Don Ledversis, the PUC’s inspector for repair and construction of state and federal pipelines. The coupling that connected the two sections of pipe was sent to a lab for a failure analysis.
The PUC issued a notice probable violation to United Civil of Middleton, Mass., the excavator hired by Spectra to work at the site. An investigation to determine if a violation occurred could take several months. United Civil has no previous violations with the PUC and faces a possible maximum fine of $350.
The leak was detected at about 8 p.m. Traffic was halted in both directions on Interstate 95 until about 11 p.m., when National Grid closed all of the valves connected to the leaking pipe.
Robert Ackley, founder of Gas Safety Inc. in Southboro, Mass., said leaks will persist as long as there is demand for natural gas. Reducing or eliminating the demand requires a wholesale transition to renewable energy, he said.