RE:Why detour?
The easy gold is on top, why go underground when you can make easy money. Yes, eventually they will go underground. But not for a very long time.
25 years life, then once thats done they drill the bottom of the pit and say, Oh, I guess the gold came from deep down! lets stick a shaft in.
KL area has many open pits, it was also going to accept all of Toronto's garabage years ago and soon Toronto's open pit garbage pit in London, Ont will be full and that option might come back to life.