Had a mapping job to do in PA a while ago and saw multiple drill sites on the aerial imagery; a support staging area an acre or two in size was lined with with an impermeable engineering membrane.
Avg. water table is ~50-100' down.
Avg. frac depth in PA, below impermeable shield rock, is usually => ~1,000 ft down.
Chances of fracking causing groundwater contamination are about 0.
That doesn't rule out foul-ups up top, but most of the site bosses are (rightly) nazis about keepin' the sh!t together.
Smart money will always bet on hysteria/agendas behind unicorn farts like this article.