As linear drainage systems do not allow for access of human beings to an underground chamber, but serve the purpose of draining water, it would be clear that channel gratings were not covered.

- Geosynthetics (membranes and textiles), geocomposites, geogrids, geomembranes and geonets to be used in roads, railways, foundations and walls, drainage systems, erosion control, reservoirs and dams, canals, tunnels and underground structures, liquid waste disposal or containment, for solid waste storage or waste disposal:

Brief description The Baixo Mondego shared municipal tip project comprises two distinct parts: - sealing of the existing tip through the construction of drains for the collection of leached water and removal of percolating water, construction of a surface drainage system and a system for removing gases and covering and compaction of the existing waste; - construction of new controlled tip adjacent to the existing one including deep and surface drainage systems, sealing of the bed, the collection and treatment of leached water and completion of support facilities.