Transmissivity evolution through interface of composite liners under applied constraint

Area of Science:

• Geotechnical Engineering
• Environmental Engineering
• Materials Science

Background:

• Geomembranes in landfill liners can develop defects, creating pathways for leachate. Non-woven geotextiles are commonly used for protection, separation, filtration, and drainage in landfills.
• Landfill operators often place geotextiles at the geomembrane-clay interface to aid welding and prevent puncture by sharp objects.

Purpose of the Study:

• To select appropriate geotextiles for landfill applications.
• To evaluate the influence of geotextiles on transmissivity within a composite liner system.
• To understand how mechanical stress and ground surface conditions affect interface transmissivity.

Main Methods:

• Conducted an investigation among landfill operators to identify common geotextile selection criteria.
• Performed transmissivity tests in a decimetric cell under 50 kPa stress with a smooth ground surface.
• Compared experimental transmissivity results with those obtained using the European standard EN ISO 12958.

Main Results:

• The transmissivity measured in the composite liner interface closely matched the results from the European standard EN ISO 12958.
• Transmissivity was found to be dependent on the mechanical stress applied to the bottom liner.
• The type of geotextile used in the interface and the nature of the ground surface also influenced transmissivity.

Conclusions:

• Geotextile selection is crucial for effective landfill liner performance.
• Interface transmissivity is a complex parameter influenced by multiple factors including stress, geotextile properties, and surface conditions.
• The findings provide valuable data for designing and managing landfill containment systems to minimize leachate leakage.