Abstract
Point sources, such as landfills, can release high concentrations of pollutant into the ground water because of migration of leachate from its bottom, which is generated primarily as a result of precipitation falling on an active landfill surface, leaching out the potential organic and inorganic contaminants from landfilled waste and discharging the same to ground water in underlying aquifer. Leachate contains a high level of dissolved solids content, high concentration of organic matter, and a trace amount of hazardous constituents. To protect the ground water from contamination by landfill leachate, it is quite essential to provide the bottom barrier of suitable thickness, and to minimize the amount of water that could enter the landfill to create leachate. The present study was undertaken to determine the rate of movement of potential contaminants from its bottom to the aquifer media, so as to evolve a rational method for the determination of thickness of bottom barrier. The study was undertaken for conservative contaminant chloride. The governing equation of contaminant transport was solved using finite difference method, and finite mass boundary condition, to ape the field conditions of landfill. The solution of the model was run in MatLab 7.0 for a range of Darcy velocities, and equivalent height of leachate. Design curves were drawn which can be used for determination of suitable barrier thickness on the basis of expected maximum concentration of contaminant in landfill leachate and maximum permissible concentration of the same in groundwater.
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