I live/ work in northern alberta. I would suggest something like muck arctic ( get slightly large for your foot) if it's too tight it will restrict blood flow and your feet will freeze.put good thick insoles in them and wear Thick wool socks and change them out as needed. Make sure the boots are big enough to accommodate both socks and insoles + a bit of extra room. A good thick chunk of foam to put your boots on while your sitting will also help ( less conduction)
if your sitting in a stand for long periods of e breaker boot blankets are nice to have in your pack. Or a good fleece towel wrapped around your feet for added R value
if your sitting in a stand for long periods of e breaker boot blankets are nice to have in your pack. Or a good fleece towel wrapped around your feet for added R value