I would rather use a lower in situ value, [due] to the remoteness of the area. something close under 10% might be more realistic.

Remoteness of the area? Are you serious? Just because there are no roads into the area yet does not make this a remote area. Canada has a long standing history of building road and railways through some of the worst terrain. We built a coast to coast railway 140 years ago, and then built a second route several years later. This was without the benefit of modern equipment.

The terrain in this case is not even that difficult. Some swamps and a couple of rock outcrops. Not like they hvae to blast their way through the Rockies. It's only 450km from the lake to the shores of Lake Superior, which is much further than needed.

Never, ever, underestimate the ability of Canadians to conquer such a minor difficulty as a stretch of land without a road.

For the record, Voisey's Bay is far more remote. They are operating as a fly in/out site for workers, where they are going to face weather extremes never heard of in Ontario, with a much shorter summer season and very long, cold winters.