If you have perforated casing and the formation no longer produces enough, you must seal the open perforation with cement before you drill down to the next aquifer.
I am sure everyone has noticed that water wells have vastly different water levels, both while static and pumping. These differences are due to formation pressure.
If you have drilled for any length of time, sooner or later you are going to stick your drill pipe. Recognizing the different ways drill pipe can get stuck is the first step in prevention — and recovery.
One of the biggest issues with nuclear power is waste disposal. At present, most nuclear power plants store their waste on site. This is a temporary fix at best.