There is too much of a risk of something breaking and polluting the area. I haven't found an instance where a sulfide mine that hasn't polluted the area and it takes somewhere from 200 to 500 years to clean the water and area. Sulfide mines are the most polluting mines there are too.
It's their first mine they are operating, so they don't have experience. A company that has operated a mine before is credible and know what they are doing. Polymet doesn't have credibility that they will do what