The East-Sullivan Mine Site: Merging Prevention and Treatment of Acid Mine Drainage
At East Sullivan, an innovative treatment of acid effluents is based on the sulphate reduction via the recirculation of water discharging around the impoundment through the organic cover. Data show that despite acid feeds down to pH 2.5, groundwater’s pH near the dispersal zone is maintained above 6. Alkalinity decreases during the recirculation, but is back up to 800 mg/L and more the following spring, thanks to sulphate reduction. Fe2+ concentrations near the dispersal zone are maintained below 2 mg/L. Evolution of dissolved iron mass in the reservoirs surrounding the impoundment suggests that the contaminated groundwater flush is completed in the north and west sectors. The east and south ones are expected to be recovered within 3 years. As expected, the wood-waste cover, besides limiting sulphide oxidation, can fill the role of alkaline reducing barrier for the treatment of acidogenic waters, until a balance between acidity and alkalinity in the effluent is reached.