Waterproofed Landfills with High-Elongation EPDM Geomembranes

Yes. EPDM is approved by the Portuguese Environment Agency as a geomembrane for MSW and NHW landfill waterproofing, when specified in accordance with DL 183/2009 (transposition of Landfill Directive 1999/31/EC) and Order 209/2004 requirements. Membriko provides complete technical documentation with CE marking (EN 13956, EN 13492, EN 13493) and Declaration of Performance per Regulation (EU) 305/2011 to support the licensing process.

EPDM has elongation of 300-450% and is a cross-linked elastomer that does not develop environmental stress cracking (ESC). Typical textured HDPE for landfills has elongation of 12-30% and is susceptible to ESC in the presence of leachate surfactant compounds — precisely the compounds present in real leachate. For landfills with expected differential settlements of 1-3 m over 10-20 m distances — normal for MSW — EPDM provides a safety margin that HDPE cannot reliably replicate under real service conditions. On irregular terrain, HDPE requires far more rigorous substrate preparation; EPDM, with its high elongation, accommodates surface irregularities without creating localised stresses that initiate ESC.

Biogas from anaerobic waste decomposition migrates vertically and can create uplift pressure beneath the cap geomembrane — if this pressure accumulates, the membrane can deform and eventually rupture or create bulges that damage the vegetation cover. The biogas drainage layer — high-transmissivity geocomposite or coarse aggregate — installed directly on the waste surface beneath the EPDM geomembrane acts as a lateral gas migration plenum to active extraction wells or passive extraction pipework. Membriko sizes this layer based on the estimated landfill gas production rate and coordinates installation of the collection pipework with the biogas utilisation or flaring design.

Not immediately, but it is recommended to protect the EPDM membrane with the cover soil layer as quickly as possible after installation and seam testing. EPDM has intrinsic UV stability (carbon black as non-depleting primary UV absorber) — ASTM G154 tests show mechanical property retention above 85% after 10,000 hours of irradiation, equivalent to 50+ years of real exposure. But unnecessary UV exposure, mechanical pressure from equipment and vandalism are always preferable to avoid. Cover soil protects the membrane and creates the conditions for establishment of the vegetation specified in the landscape restoration design.

Yes. EPDM is approved and used in both applications, but thickness and system requirements differ. For base lining, 2.0-2.5 mm EPDM is installed over the compacted mineral layer, with leachate drainage geocomposite above for effluent collection to monitoring wells and treatment. For the final cap, 1.5 mm EPDM (MSW/NHW) is installed over the biogas drainage layer, with rainwater drainage geocomposite and cover soil above. For hazardous waste landfills, the system is double at both locations.

Biogas extraction pipework penetrates the EPDM geomembrane at positions defined in the design. Membriko installs prefabricated EPDM penetration sleeves — pressure flanges or booties — that are vulcanised to the membrane and sealed to the pipe with stainless steel clamps. Each membrane-pipe seal is individually tested by pressure or vacuum before overburden placement. For active extraction pipework (with vacuum pumps), the seal must resist negative pressure up to -500 Pa — EPDM and the prefabricated sleeves are designed for this condition.

Landfill closure under DL 183/2009 includes: (1) Preparation and approval of the Closure Plan with APA — including the final cap design per Annex I, Section 3; (2) Waste surface regularisation to design profiles and slopes (3-5% minimum); (3) Final cap system installation in layers: biogas drainage, EPDM geomembrane, rainwater drainage, cover soil, vegetation; (4) Installation and connection of biogas and leachate collection systems to treatment; (5) Documentation and certification of the installed system for APA; (6) Start of post-closure period with mandatory monitoring for a minimum of 30 years. Membriko participates in phases 3, 4 and 5, providing design, installation and licensing documentation.

HDPE is typically more economical per m² as raw material — a difference of 15-30% in material cost. However, HDPE installation requires more expensive extrusion fusion welding machines, more rigorous weld quality control (destructive seam sample testing), and specialist operators. On irregular terrain or landfills with high expected settlements, the substrate preparation required for HDPE is more demanding than for EPDM. Considering total installation cost + 50-year service life (no interventions) + zero ESC risk, EPDM is competitive on whole-life cost — especially when expected settlements are high.