How do sanitary landfills collect and treat leachate?

Sanitary landfills are engineered facilities designed to prevent environmental contamination by managing leachate, a highly contaminated liquid generated when precipitation or runoff infiltrates waste cells and contacts decomposing garbage.12

To collect and treat leachate, modern landfills employ several critical systems:

• Containment: Landfills are constructed with impermeable bottom liners, typically composed of flexible plastic membranes and layers of compacted clay, to prevent leachate from migrating into the groundwater.32
• Collection: A network of perforated pipes is installed at the bottom of the landfill to capture the leachate as it accumulates. In more stringent "secure" landfills used for hazardous waste, a double-liner system is used, with a primary collection network above the upper liner and a backup system above the lower liner.24
• Treatment: Once collected, the leachate is pumped out of the landfill and transported to an on-site treatment plant or a nearby public sewerage system for processing.24

Additionally, landfills use impermeable caps to minimize the amount of water entering the waste, thereby reducing the volume of leachate produced. Groundwater-monitoring wells are also placed around the site to ensure these systems are functioning correctly and to detect any potential leaks.124