Daring Dufas:
I think she means a well pump. That's a cylindrical pump that goes right down the water well. But it's still underwater, so it's just another kind of submersible pump.

Dpb:
If the tank were waterlogged, then the diphragm in the tank is torn. So, once you emptied the water out of the tank, the air pressure on the air side of the diaphragm would also leak out. So, why would you measure 38 psi? It would seem to me that with the tank empty and the diaphragm torn, the pressure on both sides of the torn diaphragm will be atmospheric pressure, wouldn't it?