In 2013, our FS had the NSR cut-off at $6.60.  

Tecks slides confirms it's at $4.31.  From what I understand, that's a lot less waste and a lot more metal available.

"Mineral Resources are reported within a constraining pit shell developed using Whittle™ software. Inputs to the pit optimization include the following assumptions: metal prices; pit slope angles of 40–44º; metallurgical recoveries reflective of prior test work that average 86.6% for copper, 73.0% for gold and 48.3% for silver. 3. Mineral Resources have been estimated using a US$4.31/t Net Smelter Return cut-off. Mining and process costs, as well as process recoveries were benchmarked against similar projects."

MoneyK