Biggest problem with mining companies, is that they are usually obligated, by law, to maximize profits for the shareholders.
I have been in contact with Pebble's VP, Mike Heatwole, suggesting that PLP incorporate some "benefit corporation" provisions into their bylaws.
Just a few changes to their bylaws, would protect the management from civil suits from the stockholders, if Pebble took extra (and expensive) precautions to help protect the environment. This would of course take away some profits that would normally go to dividends.
It would cost a couple billion of the profits to seal and backfill the pit, during the same time that Pebble was still operating. Come on, a couple billion isn't going to really hurt anyone's bottom line, what with over 500 billion in ore.
All the "No Pebble" until you're blue in the face won't stop Pebble from opening. There's too much money involved for the fat cats to give a hoot. Instead, support PLP incorporating "benefit" provisions into their bylaws.