Description: This was a demonstration project to show that in-situ passive treatment can effectively treat AMD in the mine workings. The goal was to reduce iron concentrations, reduce aluminium concentrations, increase pH and increase alkalinity in the discharge economically. A recirculating pump was installed to recirclulate the mine pool water. Sodium hydroxide was injected to adjust the pH. Agriculutal grade mosasses was injected to promote sulfate reducing bacteria growth. After three months, the recirculating pump was shut off. Methanol was injected by gravity to continue a food source for the sulfate reducing bacteria.