that is something people are doing. Also when you go down into rock, you are able to leverage pressure as energy storage as well - which is similar to what this article is about.

There was 1 design I saw where they have a large cylinder cut out of the ground but left in place (so it is loose). Pump water underneath it to raise the cylinder up, then flip the valve and the cylinder squeezes the water back out for power through gravity. I am not sure how the sealing works on that, probably similar to hydraulics

Old mine shafts have been used.