At least they leak into the air. Sometimes they flare it off. Either way it creates air pollution.
But the newspaper article was just about leaks into the water table so, I think at least about about 6% of fracking wells are currently leaking into the ground...
Went to google and typed in fracking well leak percentage
The part of the gas well that they're relying on to protect groundwater is simply cement: about a 1-inch-thick layer between the steel casing and the surrounding rock. Cement is permeable before it sets, subject to cracking afterward and can never be made leakproof. A 1-inch layer could never be adequate when groundwater is at risk.
The gas industry's own documents and case studies show that about 6 percent of cement jobs fail immediately upon installation, and recent experience in the Pennsylvania Marcellus shale has borne this out over and over again.
Pennsylvania's Department of Environmental Protection has tracked gas leaking from wells across the state. They found 6.2 percent of new gas wells were leaking in 2010, 6.2 percent in 2011 and 7.2 percent so far in 2012.
When the cement fails, it opens a pathway for gas and other toxins involved in the drilling and fracking process to migrate into groundwater and to the surface.
http://www.timesunion.com/opinion/article/Fracking-is-hardly-leakproof-3646458.php
Gas and oil wells that lose their structural integrity also leak methane and other contaminants outside their casings and into the atmosphere and water wells. Multiple industry studies show that about 5 percent of all oil and gas wells leak immediately because of integrity issues, with increasing rates of leakage over time. With hundreds of thousands of new wells expected, this problem is neither negligible nor preventable with current technology.
http://www.nytimes.com/2013/07/29/opinion/gangplank-to-a-warm-future.html
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