Description: The SX8-D1 AMD source, which discharges from an old, buried, underground mine entry along the north bank of Brewster Hollow in the village of Defiance, had severe impacts and at times was the only source of water in the downstream segment of the stream. The final treatment system design involved installation of a mine seal that forced the water from the buried mine tunnel up into the system and uses a large flushable limestone bed (FLB) based passive treatment system.