The contamination in PA that I am familiar is the result of mishandled materials at the surface as Adak mentioned, but poor concreting could pose a problem. The lighting gas at the tap trick in Dimock, PA was common before drilling took place. I'm not saying gas companies have not or will not screw up, but Gasland intentionally misrepresented what was happening in Dimock.
Lampy and I have been having a mostly civil discussion (we all get cranky but we're both forgiving people irl)
here. And keeping those interested abreast of news items as they pop up.