Sensitivity analysis of significant parameters affecting landfill leachate generation rate

Area of Science:

• Environmental Engineering
• Geotechnical Engineering
• Water Resource Management

Background:

• Landfill design and operation significantly influence leachate generation, a critical factor in environmental management.
• The Hydrologic Engineering Center's Hydrologic Modeling System (HEC-HMS) is a key tool for simulating water balance in environmental systems.
• Understanding leachate quantity is vital for effective landfill management and environmental protection.

Purpose of the Study:

• To evaluate the governing factors of leachate quantity in a landfill using the HEC-HMS model.
• To assess the impact of design parameters and meteorological conditions on leachate generation.
• To analyze the efficacy of executive parameters within the HEC-HMS model for landfill case studies.

Main Methods:

• Utilized the HEC-HMS model to simulate leachate quantity.
• Conducted a case study at the Nazlou Landfill in Urmia, Iran.
• Analyzed scenarios involving precipitation, landfill cover design (including geomembrane presence/absence), and waste layer moisture.

Main Results:

• Lack of a final cover during the pre-closure period allows direct precipitation infiltration, significantly increasing leachate generation.
• Extreme precipitation events can lead to leachate leakage rates of up to 0.23 m³/tonne of waste.
• Removing the geomembrane layer from the final cover could increase leachate quantity by 79.38%, a challenge manageable with 76 cm of dense clay.

Conclusions:

• The presence and integrity of the final landfill cover are critical for controlling leachate generation.
• Precipitation, especially during the pre-closure phase, has a lasting impact on post-closure leachate volumes.
• Effective landfill design, incorporating adequate cover systems, is essential for mitigating leachate-related environmental risks.