Geomembranes for Containment and Barrier
topic
Geomembranes are low-permeability synthetic membrane liners (hydraulic conductivity k < 10⁻¹² m/s, up to 10⁻¹⁵ m/s for defect-free HDPE) used as primary containment barriers in landfills, mining tailings facilities, reservoirs, and canals. HDPE smooth geomembrane (1.0–3.0 mm thickness, density 0.940–0.965 g/cm³, tensile strength 20–30 kN/m, ISO 527-3) dominates landfill liner applications; textured HDPE (Ra 15–25 µm, interface friction angle δ = 20–30° with overlying soil versus 10–15° for smooth) is used on slopes >1V:3H to prevent geomembrane sliding. LLDPE (0.75–2.0 mm) provides higher flexibility and conformability for irregular subgrades; PVC (0.5–2.0 mm) for exposed pond liners and EPDM rubber (1.0–1.5 mm) for drinking water reservoirs. Thermal fusion welding (extrusion fillet weld or hot wedge dual-track weld at 300–450°C) joins panels to peel strength >200 N/mm width (ASTM D6392). Leak detection by vacuum box testing (ASTM D5641, −0.2 bar vacuum, soap solution) at all welded seams. US EPA Subtitle C hazardous waste landfill requires double liner system: primary HDPE 1.5 mm + secondary HDPE 1.5 mm with leak detection layer (transmissivity >3×10⁻⁵ m²/s). Global geomembrane market exceeds $2.8 billion.
Role
Geomembranes provide the engineered impermeable barrier that prevents leachate and contaminated water from hazardous waste, municipal solid waste, and mining tailings facilities from polluting groundwater and surface water resources, forming the critical environmental protection layer in waste containment infrastructure.