Every landfill is a water-balance problem: rain that infiltrates the waste dissolves contaminants into leachate, which pools above a composite liner as a rising head until a collection pump draws it back down. This simulator renders a real 3D landfill cross-section — waste layers, a leachate sump, the liner, and the aquifer beneath it — driven by the same water-balance and Darcy-leak equations used to design real containment systems. Tune rainfall intensity, the site's infiltration coefficient, liner integrity and pump capacity to watch the leachate head rise and fall in real time; push the liner below full integrity while the head is high and you'll see a live contamination plume breach into the groundwater below, with a running tally of cumulative leaked volume and a smoothed risk indicator.