Pebble says their mine will be small. Don't believe them.

The Pebble 12% Build is the most recent mine proposal presently being evaluated by the US Army Corps of Engineers in an Environmental Impact Statement.[1] The proposed mine would mine only 12% of the identified mineral resource over the 20-year life of the mine. The smaller, ‘environmentally friendly’ mine proposed by the Pebble Limited Partnership would put all of the acid-generating waste back into the open pit to minimize post-closure water treatment requirements, but perpetual water treatment would still be required.