Historically, underground hard rock mines are abandoned after the ore is mined out. Water then seeps into the fractures, mined out veins, and other mine workings where it combines with oxidized minerals to form sulfuric acid which then brings heavy metals into solution which then flows out as acid mine drainage (AMD). The AMD impacts the surrounding streams by providing a steady influx of acidic metal rich water, as well as surges of AMD from the collapse of underground dams where AMD has pooled. Such surges and sometimes all flows can be controlled by installing concrete plugs (bulkheads) in strategic locations. This webinar will address underground bulkheads in general and will present specific examples from Region 8 of bulkhead installations and water quality changes, including those at Dinero Tunnel, Pennsylvania Mines, and Captain Jack Mill sites. To view this archive online or download the slides associated with this seminar, please visit http://www.clu-in.org/conf/tio/Mining-Bulkhead_102519/