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Bottom and top seals

A geomembrane system serving as a top or bottom seals is often utilized to isolate contaminants, directly safeguard the environment, or protect against potential future pollution. Bottom seals are notably used in facilities like tank terminals, while a combination of bottom and top seals is often found in landfill sites.

Such sealing processes require execution under a certificate of installation by a certified entity. Since 1997, Genap has maintained the rigorous KIWA certification, underscoring our commitment to quality and environmental protection.

Typically, a 2mm HDPE geomembrane is used for both types of seals. This specification aligns with current guidelines for the use of geomembrane constructions to protect the environment and/or comply with landfill base protection regulations. For top seals, the geomembrane might feature a textured surface to prevent the slippage of the sand layer on slopes. Depending on the project, our engineering department offers tailored advice on the necessary geomembrane for a secure slope construction, including the potential need for additional elements like drainage mats or geogrids.

The desired dimensions and shapes of the geomembrane seal are assembled on-site from rolls of approximately 7 meters wide. Here at Genap, we have the capability to tailor-make openings and fittings for pipelines, concrete structures, and beacon enclosures.


Mark Visser
Your horticulture specialist
Mark Visser
Sales Manager Civil projects