Danger in honeycomb of old wells
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Gas company employees must test this temporary vent to see if it's safe for Nick Kellington and his family to visit their home. The Kellingtons were evacuated after gas from a nearby abandoned well caused a small explosion in West Mifflin.
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In the last 150 years, prospectors and energy companies have drilled as many as 12 million holes across the U.S. in search of oil and gas. Many were plugged after they dried up. But hundreds of thousands were simply abandoned and forgotten, often leaving no records of their existence.
Government reports have warned for decades that abandoned wells can provide pathways for oil, gas or brine-laden water to contaminate groundwater supplies or to travel up to the surface.
New wells sometimes disturb layers of rock and dirt near fragile old wells, leading to new cases of contamination. For Pennsylvania and other states sitting on top of the Marcellus Shale formation, the rapid growth of gas drilling may increase the danger of such contamination.
Abandoned wells have polluted the drinking water source for Fort Knox, Ky., and leaked oil into water wells in Ohio and Michigan. Similar problems have occurred in Texas, New York, Colorado and other states where drilling has occurred.
In 2008, gas from an abandoned well leaked into a septic system in Pennsylvania and exploded when someone tried to light a candle in a bathroom, killing the person, according to a 2009 draft report by the state Department of Environmental Protection. That report also documented at least two dozen other cases of gas seeping from old wells, including three where the drilling of new wells "communicated" with old wells, leaking gas into water supplies and forcing the evacuation of a home.
In February, methane from an old well made its way into the basement of a house in West Mifflin, triggering a small explosion. Two families were evacuated and have not yet returned.
Such incidents rarely receive much attention outside the states and neighborhoods they affect. But as the nation's latest drilling boom continues, abandoned wells have begun attracting more attention, particularly in states where the earth is already pock-marked with holes left by earlier waves of extraction.
The most recent effort to count the nation's unplugged wells was a survey published in 2008 by the Interstate Oil and Gas Compact Commission, a multistate agency made up of regulators and industry representatives. It found that states had located nearly 60,000 wells that needed to be plugged, and estimated that as many as a million more may be out there.
First Published April 4, 2011 12:00 am
