I'm a mechanical engineer myself & would not have blind faith in...

I'm a mechanical engineer myself & would not have blind faith in any contractor. A project this size means someone like CPB, flour, langs, FH... None of which I would trust with a bar of soap. Comes down to hope that the consultant known their sheet, the design and contract are watertight, and follows through like a hawk. So so risky

Those engineers in the 70's arn't around any more, much less on this project. When was the last large scale underground pumped hydro project? in the world? let alone Australia? Key bit is underground.

It can & probably will be done. I'm just very doubtful of the budgets and their basis for accuracy.

I can't quickly find original budgets and costing on the Kangaroo Valley project, can you?