from activistpost.com: 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.
A dozen of the leaks could have posed explosion risks, the researchers
said. Some manholes had methane concentrations as high as 500,000 parts
per million of natural gas – about 10 times greater than the threshold
at which explosions can occur.
Four months after phoning in the leaks to city
authorities, the research team returned and found that nine were still
emitting dangerous levels of methane. "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 who led