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.