Here's an interesting article about the Wivenhoe Pumped Hydro facility.
http://reneweconomy.com.au/wivenhoe-pumped-hydro-big-little-plant-didnt-30606/
Apart from the operational shenanigans, it is interesting that the round trip efficiency is estimated to be 66% (about the same as Snowy Hydro 2) whereas typically Pumped Hydro seems to be in the 70-80% range (https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity)