EPA, Forest Service, Rosemont on the issues

Here are key points of the Forest Service’s draft environmental impact statement for the Rosemont Mine, and what the Environmental Protection Agency found wrong with it.

GROUND WATER QUALITY

FOREST SERVICE: Says infiltration of pollutants into the aquifer through the mine’s tailings, waste rock and heap leach facility should be negligible. Water storage near the surface is expected to be sufficient to ensure that rainfall that doesn’t immediately run off will be lost to evaporation or plants before seeping underground.

Heap leaching, in which a sulfuric acid solution is used to dissolve copper, will last six years. Then and for three years afterward, the mine will collect and treat seepage and reduce concentrations of contaminants below state standards. When it’s closed, the leach facility will be encapsulated with waste rock to prevent liquids from infiltrating through it.

EPA: Says the Forest Service understates expected contaminant seepage levels and risks that the mine could pollute ground and surface water with contaminants such as arsenic and selenium.