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.
