Consequences of raising the height of a landfill in a water-deficient climate

A large-scale field experiment has been carried out at the Coastal Park landfill which serves the City of Cape Town, South Africa. The landfill is unlined, and the City Council was under pressure from the central Government to cap and close the existing landfill and to establish an extension to the landfill with a lining to prevent the escape of leachate into the ground water. Measuring cells, installed to measure the rate of leachate flow from the landfill had shown that over a period of 9 years, from 1987 to 1995, leachate flow had averaged only 2% of rainfall. It therefore appeared possible, by increasing the moisture absorption capacity of the landfill, i.e., by increasing its height, to stop the leachate flow completely. If this could be achieved, there would be no need for a lining, and the raising would considerably extend the life of the landfill.The paper describes the experiment and its results, including the effects of the raising on leachate flow, settlement, leachate quality and the potential for polluting ground water, and the landfill’s water balance.