Design of gas collection systems: Issues and challenges

Area of Science:

• Environmental Engineering
• Geotechnical Engineering
• Waste Management

Background:

• Designing effective landfill gas collection systems (GCS) requires accurate estimation of parameters like radius of influence (ROI) and well spacing.
• Estimating the ROI for a specific landfill presents significant challenges in GCS design.

Purpose of the Study:

• To estimate the radius of influence (ROI) for the Bagalur landfill under various gas generation rates.
• To analyze ROI for active and passive GCS using numerical modeling at different suction pressures.
• To calculate optimal well spacing and assess GCS design efficiency.

Main Methods:

• Two-dimensional numerical modeling was employed to estimate ROI for active and passive GCS at varying suction pressures and gas generation rates.
• An inverse correlation between different ROI definitions and gas generation rates was investigated.
• Three-dimensional modeling was used to assess the efficiency of the calculated well spacing and GCS design.

Main Results:

• An inverse correlation was observed between various ROI definitions and gas generation rates, explained by conceptual differences.
• Active and passive GCS achieved average methane recovery rates of 88% and 84%, respectively.
• Low atmospheric methane flux (10^-9 to 10^-10 kg m^-2 s^-1) indicated high design effectiveness.

Conclusions:

• The study successfully estimated ROI for the Bagalur landfill, providing insights into GCS design parameters.
• The validated methane flow rates suggest the model's usability for future landfill gas management investigations.
• The developed GCS design demonstrates high methane recovery efficiency and minimal environmental impact.