Meethotamulla open dump (MOD) of Sri Lanka that has received about 290,000 metric tons of mixed MSW annually collapsed on 14th April 2017 with massive devastation. An integrated approach was attempted to control further collapse with the deployment of drone-assisted and stand-alone instrumentation. The collapsed dump was analyzed for attributes, including contours, heights, wetness, temperature levels, tension cracks, landfill gases, fire, explosion, and asphyxiation hazards with 24-h surveillance after one day of the collapse. The mode of MOD failure was implicated to be deep-seated (rotational) slope failure. A short-term plan, consisting of 12 activities was prepared and successfully implemented. The activities of the short-term plan were carried out at the dumpsite until the water level fluctuations <5 cm, inundation of the toe area receded completely, the horizontal displacement of surface markers <20 mm, lower explosive levels of CH4 and CO less than 5 and 12%, respectively, O2 level improved up to 21%, and temperature variation of the collapsed face <2 °C. The short-term plan was halted when the factor of safety for slope failure of the critical face improved from 0.807 to 1.286 ensuring no signs of a subsequent collapse of the MOD. An early warning system was established in the case of an imminent collapse. This integrated approach, to our knowledge, is the first study instituted, and this holistic management effort could be easily replicated to avoid disasters from slope failures of landfills or open dumps that may occur elsewhere.
Keywords: Landfill gas; Municipal solid waste management; Open dump; Rehabilitation; Slope failure; Stability.
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