January 16, 2014
Thousands Of Natural Gas Leaks Under The Streets Of DC
[ Watch the Video: More Than Hot Air - Explosive Find Under Washington DC ]
Lee Rannals for redOrbit.com - Your Universe Online
According to a study published in the journal Environmental Science & Technology, there are nearly 6,000 natural gas leaks under the streets of Washington, DC. Scientists from Duke University and Boston University say that they have discovered more than 5,893 leaks from aging natural gas pipelines under DC.
The team also said that dozens of these leaks could pose an explosion risk, and some manholes have methane concentrations as high as 500,000 parts per million, which is about 10 times more than the threshold at which explosions occur.
"Finding the leaks a second time, four months after we first reported them, was really surprising," Robert B. Jackson, a professor of environmental sciences at Duke who led the study, said in a statement. "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."
Natural gas pipeline failures cause an average of 17 fatalities, 68 injuries and $133 million in property damage annually around the nation, according to the US Pipeline and Hazardous Materials Safety Administration. These leaks also pose threats to the environment because methane is the primary ingredient for natural gas and a high contributor to the greenhouse gases. Pipeline leaks are the largest human-caused source of methane in the US and contribute to $3 billion of lost and unaccounted for natural gas each year.
The team mapped out gas leaks under all 1,500 miles of road within DC using a high-precision Picarro G2301 Cavity Ring-Down Spectrometer installed in a car. Tests confirmed that the isotopic chemical signatures of methane and ethane found in the survey closely matched that of pipeline gas.
According to the study, the average methane concentration in the Washington 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, which is about 45 times higher than normal levels.
"Methane emissions from these four leaks ranged from 9,200 to 38,200 liters per day for each leak - that's comparable to the amount of natural gas used by between 2 and 7 homes," Duke PhD student Adrian Down said in a statement.
The same team mapped out more than 3,300 natural gas pipeline leaks last year beneath the roads of Boston, which consisted of about 785 road miles.
"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.
Jackson said this study needs to be used to help motivate the local government to take action by putting the right financial incentives in place. "Companies and public utility commissions need help to fix leaks and replace old cast iron pipes more quickly,” he added.
Image 2 (below): This is a satellite image of the District of Colombia with bar charts showing where natural gas leaks were located under city streets and in what concentration methane was identified. Higher bars indicate higher concentrations in parts per million. Credit: Duke University