We've known for a long time that mining can come with harmful by-products, but Canada has often been slow to put this knowledge into action. And that's a big part of how a veritable mountain of arsenic — enough to kill everyone in this country — ended up entombed in the ground on the outskirts of Yellowknife, just across the bay from the Yellowknives Dene First Nation.How did it get there? What are we doing about it? What happens as the frozen ground up there gets warmer in the years to come? These aren't pleasant questions, but sometime soon we're going to need some decent answers.GUEST: Eva Holland, freelance journalist writing for The Walrus We love feedback at The Big Story, as well as suggestions for future episodes. You can find us:Through email at hello@thebigstorypodcast.ca Or @thebigstoryfpn on Twitter