The number of denials is very small, and even though there is no appeal mechanism, nothing prevents a proponent from re-submitting a new application with a set of different mitigation measures. In the case of those we couldn't accept, as David mentioned, it's either because the mitigation measures were not accepted by the proponent or what the proponent proposed was not acceptable to us.
But there's a discussion, and if we can't agree on what's needed.... For instance, if vessels need to continue to pass during the construction and the proponent doesn't want that, well, it's unlikely we'll resolve this. But in the vast majority of cases, there is always a compromise possible from both sides.