If it's in "very very deep" shale rock, then the potential problems with fracking are pretty much nil.
You are either basing this on ground hole pressure or the thought that water stays in the ground during the fracking process, both of which are incorrect.
Nope. And by "nope" I don't mean that you're wrong, but that neither of those match the reason I'm basing this on.
Drinking water is usually only within the first couple thousand feet down and drilling is primarily 5-6k feet down with some exceptions closer to 9-12k feet. The drinking water contamination occurs when the fracking liquids are returning to the surface and leak out of the casing.
Drinking water contamination specific to fracking (ie: not potentially present in any other form of drilling) occurs when the fracking is being done on a layer that is very near to the water table. This causes gasses from the layer broken up by the process itself to mix with the water. This is a result of earlier attempts at the process which were not deep enough. If the layer of shale is "very very deep", it will be well below the water table and well outside any danger of direct contamination.
Obviously, any time you are drawing material out of the earth which passes through the water table there is a chance of some contamination, but that's not specific to fracking. Same thing can happen with normal oil wells, gas taps, etc. This is one of the issues that is grossly misstated about fracking in order to make it sound like it's somehow inherently more dangerous than other methods of drilling. If the layer of material being fracked is deep enough, it's just as safe as any other drilling method in terms of potential contamination.
Fracking = pumpling salt water and chemicals into the well which attracts gases, liquids, and oil and then returns to the surface where it is all separated.
It's a little more involved than that. The whole point of pumping the water into the rock is to offset the natural pressures the ground places on itself (which tends to hold the oil and gas in place), allowing said oil/gas to be released out through the well. The danger is based on where you're fracturing the rock layer. If it's close vertically to a water layer, then gasses can be released through the earth itself into that water layer causing contamination. If it's deep enough, the fracturing process wont allow gas to escape far enough through the ground (cause there's still pressure to consider) to reach the water layer.
That's why this is largely a myth that Hollywood perpetrates on us about this issue. That's not to say it can't happen (or even hasn't happened), but that current methodologies and restrictions make it unlikely that it will happen. The correct response isn't to blindly fight against fracking, but to makes sure that proper regulations are in place to ensure it's only done in layers deep enough to ensure no direct contamination of a water supply can happen. Again though, if the shale in this case is "very very deep", there's no danger of that happening. The only way oil or gas could get into the water layer is via the drill well itself. And at the risk of repeating myself, that's a risk that can happen in any form of well. The fracking process itself has no effect on that at all.