Taconite mining creates a lot of waste rock. After thirty years of dumping the rock, or tailings as the miners call it, the Evtac facility near Eveleth has just about filled its dump. Now the company faces a new challenge: return the rock pile to a natural looking landscape. Evtac has been looking at a number of options, and as Minnesota Public Radio's Stephanie Hemphill reports, the hot favorite appears to be what the experts call bio-solids, and the rest of us call sewage sludge. Turning iron ore into taconite creates twice as much waste rock as taconite. Since the Evtac mine opened over 30 years ago, waste rock has been piled in one place. The pile is now a mountain a mile long, a mile wide and 150 feet high. It looks like a lunar landscape, and it's virtually sterile.