Slope stabilization of coal mine overburden dumps: life cycle environmental sustainability assessment of alternatives

The stability of coalmine overburden dumps is a crucial aspect and often requires a slope stabilization method in place to prevent slope failures. Mechanical methods like benching, gabion wall construction, geogrid reinforcement, and biological methods like the use of vegetation can suffice the need for slope stabilization. In this study, a life cycle assessment of the above-mentioned methods was performed to obtain the environmental impacts through various midpoint impact categories considering a "cradle-to-site" assessment. The system boundary for each method was created using the involved activities and associated equipment and energy needs. The Ecoinvent 3.0 database and TRACI assessment method were used to perform the life cycle impact assessment using SimaPro software. The results show that the use of vegetation caused the least impact. The highest impact under the majority midpoint categories was caused by geogrid reinforcement followed by benching, which was mostly attributed to the geogrid production and OB handling activities, respectively. The carcinogenic, followed by ecotoxicity and fossil fuel depletions, were the most impacted categories for the mechanical methods, which may be due to the release of chemical pollutants during material production or handling. Adherence to the overburden dump management guidelines and the use of renewable sources of energy are the two major aspects that can drastically curb the emission load on the environment, thus inching towards the goal of sustainability while adopting slope stabilization measures for overburden dumps. Besides imparting stability, plants provide a diverse solution to the other ills associated with the overburden storage and management.