> "Dyke" is a wholly different noun. I advise against its use until you understand it better. Perhaps you could refrain from making snarky comments about minor

> "Dyke" is a wholly different noun. I advise against its use until you understand it better. Perhaps you could refrain from making snarky comments about minor spelling errors which clearly didn't impact your understanding until you understand dyslexia better? > The bottom of the reservoir needs to be impermeable. It is well understood by civil engineers how to achieve this. Understood isn't the same as economically feasible. It's not a trivial issue. > Earth-moving equipment is very good at getting to places you would not want to try driving your car into Earth-moving equipment isn't designed to make long distance overland journeys. They are typically delivered to a work site at most hundreds of yards from where they are needed. > Generation and pumping equipment remains at the bottom of the hill You still need to get the equipment there so the bottom of the hill needs to be near a road. And you don't want miles of penstock because that will reduce the dynamic head pressure due to friction losses. The point is there are constraints which you are pretending just don't exist.