"I find it hard to believe that it's often 1 a problem," retired geologist Philip Coleman says. "Well fracturing was old news back in 1977. We did thousands of fractures, and this was in Medicine Hat [Alta.] country, so they were all related to shallow gas. We fracked wells. They were only 400-600 metres in depth, but below freshwater aquifers. To my knowledge, we never, ever created a problem." He shrugs. "The new wells that we're involved in are between 1,000 and 1,500 metres in depth. In the scope of the oil industry, that's pretty shallow. In one in 100,000, it is possible [to have a problem], I suppose, but I am not aware of it happening."
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