WHAT IS ACID MINE DRAINAGE?

Acid mine drainage, or “AMD”, is a toxic discharge associated with mining. When rock is disturbed by mining, sulfur‐rich minerals, such as Pyrite (iron sulfide), that are usually trapped underground come into contact with air and water. When it reacts with air and water, Pyrite forms ferrous iron and sulfate; both of which are highly acidic. These acids in solution with water dissolve heavy metals from nearby rocks, such as iron, manganese, and aluminum. The result is acidic, heavy metal laden water is called acid mine drainage