Description: The Whisky Run #9 treatment system is designed to passively remove aluminum, iron, and manganese and add alkalinity to the watershed. The discharge is net-neutral to weakly net acidic (average 7.6 net alkaline) and contains low levels of iron (average 1.9 mg/L) and aluminum (average 3.5 mg/L) and some manganese (average 9.3 mg/L). The treatment strategy incorporates limestone to ensure a net alkaline discharge and ponds plus densely vegetated wetlands for retention of particulate metals (Fe and Al) and a long limestone channel for final polishing and manganese removal.