Modelling flow to leachate wells in landfills

Area of Science:

• Environmental Engineering
• Geotechnical Engineering
• Hydrogeology

Background:

• Vertical wells are essential for landfill dewatering, especially in older sites lacking basal collection systems or newer sites with failed infrastructure.
• Effective leachate level control is critical for landfill stability and environmental protection.

Purpose of the Study:

• To investigate the transient dewatering process in landfills using vertical wells.
• To analyze the impact of seepage faces on landfill dewatering efficiency.

Main Methods:

• Utilized the numerical groundwater flow model MODFLOW-SURFACT, which incorporates seepage surface modeling capabilities.
• Simulated transient dewatering scenarios in a landfill environment.

Main Results:

• A seepage face develops at the well entry during pumping, influencing the expected drawdown.
• The position of the seepage face significantly affects the groundwater flow field around the well.

Conclusions:

• The development and position of the seepage face are critical factors in landfill dewatering.
• Accurate characterization of the seepage flow field is necessary for optimal vertical well design in landfills.