Field Trip 3 – Passive Treatment of Acidic Mine Drainage

Sev­er­al pass­ive sys­tems treat­ing highly acid­ic mine drain­age with elev­ated alu­min­um and iron will be vis­ited. One site util­izes low-pH iron remov­al with a ter­raced iron form­a­tion. This is pre­ced­ing a multi-stage acid neut­ral­iz­a­tion sys­tem where a lime­stone pond is flushed into a set­tling pond fol­lowed by a mixed media ver­tic­al flow pond and wet­land. A second stop will include a newly expan­ded sys­tem for a severely degraded dis­charge (>400 mg/L CaCO₃ acid­ity). It uses sol­ar-powered valves to flush two lime­stone ponds in series with set­tling ponds fol­lowed by a mixed media ver­tic­al flow pond and wet­land.