How do liners in sanitary landfills protect groundwater?

In sanitary landfills, impermeable liners are critical engineering components designed to protect groundwater from contamination by leachate—a highly contaminated liquid generated when precipitation or surface runoff infiltrates decomposing waste.123

These liners act as a physical barrier between the buried refuse and the underlying soil and water table. They are typically constructed using a combination of flexible plastic membranes and layers of compacted clay, which is naturally resistant to water flow.2314

By preventing leachate from percolating downward, these liners ensure that hazardous liquids do not reach or mix with groundwater supplies. To further enhance safety, modern landfills often incorporate a network of perforated pipes above the liners to collect leachate for treatment, as well as groundwater-monitoring wells to detect any potential leaks. This multi-layered approach is essential for maintaining public health and preventing environmental pollution.2315