More Than 5000 Natural Gas Leaks Found under Washington, D.C.

News that the nation's capital contains thousands of gas leaks at risk of explosion has generated a buzz.

More than 5,893 gas leaks from old natural gas pipelines were found under the streets of Washington, D.C.  and dozens of locations had high concentration of methane gas, large enough to cause an explosion.

A team of researchers from Duke University and Boston University detected more than five thousand gas leaks using a high precision Picarro G2301 Cavity Ring-Down Spectrometer fitter in a GP equipped car. Gas leaks under all 1,500 road miles within Washington were analyzed. This was done in collaboration with Gas Safety Inc.

The researchers noticed that the concentration of methane in some manholes was as high as 500,000 parts per million of natural gas, 10 times more than the threshold at which explosions take place. Even four month after informing the city authorities about the leaks the team found that some locations were still emitting gas and no action had been taken.

"Finding the leaks a second time, four months after we first reported them, was really surprising," said Robert B. Jackson, a professor of environmental sciences at Duke, the study lead. "Repairing these leaks will improve air quality, increase consumer health and safety, and save money. Pipeline safety has been improving over the last two decades. Now is the time to make it even better."

Data according to the U.S. Pipeline and Hazardous Materials Safety Administration reveals that annually there is an average of 17 fatalities due to gas leaks, nearly 68 injuries and $133 million damage to property.

Lab analyses confirmed the isotopic chemical signatures of methane and ethane from the pipelines.  The methane gas leak was 2.5 times more than what is found in the city air samples and also a few leaks had concentration 45 times higher than normal levels.

Measurement of concentration of methane from four different street level leaks showed a variation of 9,200 to 38,200 liters per day for each leak.

 "The average density of leaks we mapped in the two cities is comparable, but the average methane concentrations are higher in Washington," said Nathan G. Phillips, a professor at Boston University's Department of Earth and Environment.

Last year, nearly 3,300 natural gas leaks were identified under 785 road miles in the city of Boston.

Critics commenting on this finding state that the news has triggered unwanted alarm. Denying the news of over 5,000 gas leaks, Betty Ann Kane, chairwoman of D.C. Public Service Commission claimed that no tragic accident or explosion had been witnessed in the last 20 year.

The finding was documented in the journal Environmental Science & Technology.