Assessment of Municipal Solid-Waste Landfill Liner Performance

Area of Science:

• Environmental Engineering
• Geotechnical Engineering
• Waste Management

Background:

• Landfill liner systems are critical for environmental protection, preventing leachate contamination.
• Performance assessment of primary liner systems in municipal solid-waste landfills is essential for regulatory compliance and environmental safety.

Purpose of the Study:

• To evaluate the performance and efficiency of primary liner systems in municipal solid-waste landfills using leachate collection system (LCS) and leak detection system (LDS) data.
• To compare the actual leakage rates with estimations from the Hydrologic Evaluation of Landfill Performance (HELP) model.

Main Methods:

• Analysis of flow rate data from LCS and LDS across 54 landfills in seven US states with double-liner systems.
• Calculation of aggregated liner system efficiency based on collected leachate volumes.
• Comparison of observed leakage rates with HELP model predictions for different liner types (composite vs. geomembrane).

Main Results:

• The aggregated efficiency of primary liner systems was found to be over 98%, assuming complete leachate collection.
• No statistically significant difference in collection efficiency was observed between composite liners and geomembrane-only liners (median of 99% for both).
• The HELP model tends to overestimate leakage for geomembrane liners but underestimate it for composite liners, given default defect parameters.

Conclusions:

• Primary liner systems in municipal solid-waste landfills exhibit high collection efficiency.
• Composite and geomembrane-only primary liners demonstrate comparable performance in terms of leachate collection efficiency.
• The HELP model's leakage estimation equations may require recalibration for accurate prediction of liner performance, considering potential groundwater intrusion into the LDS.