Stuxnet was not the worst

http://en.wikipedia.org/wiki/Siberian_pipeline_sabotage a 3kt explosion that by pure chance occurred in a remote part of Siberia rather than a major city.

High pressure gas pipelines are now rather common across Europe and north America.

But of course it couldn't happen here - US and UK oil companies are famous for the lengths they will go to with expensive multiple redundant safety systems to prevent any possible accident.