For Teck to back-in for 75% and spend 4x CUU's past expenditures (~$80M) they must believe that SC, with ~$320M of new capital to be invested by Teck (as part of the back-in obligation), is worth at least ~$425M ($80x4/0.75). Basically Teck just needs to like the project and give some value for what CUU has spent to date.

Teck might then question why a project with effectively a zero after-tax NPV ($67M after spending $4.5B) in the BFS is worth spending more money on. SC may have huge exploration upside and district potential but it really isn't Teck's business model to spend on greenfield, "blue sky" exploration. The whole purspose of the SC option was to let a junior (i.e. CUU) prove this potential exists in a BFS.