Your numbers seem a bit off. Teck's cash flow is quite a bit higher but so are their expenses. Teck's cash flow is currently around $2.8B per year. This may sound impressive, but keep in mind they are also spending $430M per year on debt interest, $520M per year on dividends, and $740M per year on sustaining capex. This assumes that Teck does not pay off any debt and simply rolls it forward into new debt.

This leaves Teck with about $1.1B to spend per year on new projects in order to sustain their current cash level of $2.3B. Fort Hills will cost about $735M per year and Schaft Creek will cost about $800M per year. This means Teck will be spending about $435M per year more than it earns and that's excluding money for Teck's other new projects.

Teck does have $2.3B in cash and a $2B line of credit so they can definitely pull it off, but it puts them in a tough spot financially.