Lining a New Landfill near Porto

Maccaferri Lines New Landfill Near PortoWith a combined population of 440,000, the communities of Santa Maria da Feira and Vila Nova de Gaia, Portugal, produce 175,000 tons of solid waste annually. Waste management is overseen by the Multi-municipal System of Sul do Douro (Suldouro), which established a project to construct a new landfill. The existing one was nearly full.

DST Group was selected as the main contractor and Maccaferri of Portugal was called to provide a robust, impermeable, geosynthetic barrier system for the Canedo site.

The rock strata on site, and specifically where the main part of the cell was to be construction, posed a major challenge. Careful excavation and the use of explosives were required. Following these works, Maccaferri’s thick, performance-oriented geotextile MacTex® N80.1 was installed and covered with sand to provide a protection and separation layer beneath the primary sealing component.

The main cell was designed for 110,000 m2 of space. Related to this was a 4500 m2 leachate lagoon and two smaller treatment ponds of around 2000 m2. Maccaferri’s MacLine® SDH 200 was used as the primary liner and Maccaferri MacLine® GCLW20 was used as the secondary liner.

The primary liner is a 2mm thick HDPE geomembrane with a smooth finish on both faces. This MacLine® SDH 200 membrane contains 3% of carbon black, antioxidants, and thermal stabilizers to ensure robust performance and a long design life. In addition, the geomembrane does not contain plasticizers or fillers that could migrate over time under UV or other degradation effects.

The geomembranes were delivered in efficient rolls and the panels were welded together on site. All welded seams were tested for water-tightness and fluid leakage, prior to the construction quality assurance (CQA) personnel approving the installation work.

The geosynthetic clay liner (GCL), which served as the secondary sealing component, is a 7mm thick material with a core of high-swelling bentonite encapsulated between two robust geotextiles. The integrated matrix of bentonite and needlepunched fibres provides high shear strength and allows the GCL to offer low permeability even when installed in adverse conditions. Whenever construction work is carried out on a soft surface or in soil subjected to landslides, there is a possibility of collapse or landslide; here, the GCL’s high internal shear strength helps secure the lining system’s integrity on steep slopes.

During the new landfill works, unexpected water flow was encountered in the excavated strata. Maccaferri and the designers developed a solution using MacDrain® W1051 drainage geocomposite to safely collect this water and transfer it away from the cell.

Learn more about Maccaferri’s products, engineering solutions, projects and global offices at http://www.maccaferri.com/.

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