Emergy and Carbon Footprint Analysis of the Construction of Passive and Active Treatment Systems for Net Alkaline Mine Drainage

Multi-criteria sustainability assessments were completed for the construction of a net-alkaline mine drainage passive treatment system (PTS) in northeastern Oklahoma to compare resource use and greenhouse gas emissions with a hypothetical active treatment system (ATS) alternative. Emergy analysis, an environmental accounting method assessing resource use, and carbon footprint analysis, a tool to evaluate greenhouse gas emissions, were completed for the construction of both systems. Assessing sustainability using multiple criteria is important in evaluating systems on the basis of resource use and environmental impact. Construction of the hypothetical ATS required seven times more emergy purchased from the economy and emitted three times more carbon dioxide equivalents than construction of the PTS. Concrete was the largest factor in both the emergy analysis (ATS and PTS) and carbon footprint (ATS only). Diesel fuel was the largest factor in the carbon footprint of PTS construction. This multi-criteria sustainability assessment shows that a hypothetical ATS alternative to the PTS would have used more resources and emitted more greenhouse gases during construction.