More than 5,893 leaks from aging natural gas pipelines have been found under the streets of Washington, D.C. by a research team from Duke University and Boston University.
Nationally, natural gas pipeline failures cause an average of 17 fatalities, 68 injuries, and $133 million in property damage annually, according to the U.S. Pipeline and Hazardous Materials Safety Administration.
In addition to the explosion hazard, natural gas leaks also pose another threat: Methane, the primary ingredient of natural gas, is a powerful greenhouse gas that also can catalyze ozone formation. Pipeline leaks are the largest human-caused source of methane in the United States and contribute to $3 billion of lost and unaccounted for natural gas each year.
Researchers from Boston University and Gas Safety, Inc., mapped gas leaks under all 1,500 road miles within Washington using a high-precision Picarro G2301 Cavity Ring-Down Spectrometer installed in a GPS-equipped car. Laboratory analyses then confirmed that the isotopic chemical signatures of the methane and ethane found in the survey closely matched that of pipeline gas.
The average methane concentration observed in the leaks was about 2.5 times higher than in background air samples collected in the city. Methane levels in some leaks were as high as 89 parts per million, about 45 times higher than normal background levels.
Last year, the team mapped more than 3,300 natural-gas pipeline leaks beneath 785 road miles in the city of Boston. The average density of leaks mapped in the two cities is comparable, but the average methane concentrations are higher in Washington.
The new study comes at a time when the nation's aging pipeline infrastructure is generating increased legislative attention. Last November, Sen. Edward J. Markey (D-Mass.) introduced two new bills to speed up the replacement of natural gas pipelines in states with older infrastructures by offering new federal programs and incentives to help defray the costs associated with the repairs. (Science Daily, 1/16/2014)