Abstract: A landfill 10 is lined with an impermeable liner material at 12 and filled with waste, such as household waste. When the landfill is full, it is capped by a cap 14. Degradation of the body of waste material within the landfill creates leachate liquid as a byproduct. Without intervention, the leachate will form a layer 16 of saturated waste material at the bottom of the landfill 10. An extraction well 22 allows leachate to be drawn from the landfill 10 by a pump 26. Injection wells 24 allow leachate to be reintroduced into the landfill 10. Various sensors 36, 38, 40 take measurements associated with the wells 24. Leachate delivery is controlled in accordance with the values obtained. The obtained values may include the leachate head in the well and/or the volume or rate of leachate delivery to the well and/or the elapsed time since commencement of leachate delivery to the well and/or the rate of dispersion of the leachate into the landfill from the well.