The Giant Mine in the Northwest Territories, near Yellowknife, Canada, estimated to be the biggest environmental clean-up in Canadian history. The mine operated from 1948 to 2005 and produced 220 tons of gold. It covers 900 hectares just outside Yellowknife along the shores of Great Slave Lake. There are about 100 buildings, 25 large piles of junk and rusting machinery, 30 kilometers of road, eight open mine pits, six tailings’ ponds, and 13 underground chambers still exist on the site.
13.5 million tons of arsenic-contaminated soil is on the surface; 237,000 tons of arsenic trioxide is in underground chambers; and an unknown amount of asbestos is in buildings on the site. The plan is to freeze underground arsenic in perpetuity, pump and treat seepage from mine in perpetuity, and attempt to destroy the hazardous waste. The aim is to remediate parts of the site to residential standards and others to industrial standards. The goal is to be completed by 2031.