Sorry to reply again. The well on my family farm is a few dozen feet deep, and the bore holes are 5k feet deep and capped at a depth of 3k ft. The farm sit on a massive amount of clay, which is actually great for this kind of thing because clay seals itself under pressure. The proposed French sites are all in clay. I'd be happy to host a site there, or a similar facility near where I actually live.

A deep borehole is super deep compared to a well.