These 5 manmade holes have proven themselves to be testaments to the human will and skill of engineering, all in all making up over 10 miles of deep excavation. Lucky for us here in the United States, Montana and Utah feature two entries on the list—and you may not expect them.
The Superfund program was created in 1980 and actually has a much more complex name: the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). All the most toxic sites in the country were basically put on a list, and hopes were high that somehow, some way, sometime - they'd get 'cleaned up'.